GH-8643: Replace synchronized with Lock

Fixes https://github.com/spring-projects/spring-integration/issues/8643

* First pass - trivial synchronized blocks
  - Convert the "trivial" `synchronized` block into `ReentrantLock`.

* fix checkstyle

* use blocking lock

* Secon pass - handle multi-lock cases

* javadoc + year

* addres first batch of review suggestions

* fix checkstyle issues

* fix the mqtt parent/child lock monitor sharing

* fix the mqtt parent/child lock monitor sharing, v2

* patch the stomp test

spring-integration-amqp/src/main/java/org/springframework/integration/amqp/outbound/AbstractAmqpOutboundEndpoint.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2022 the original author or authors.
+ * Copyright 2016-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,8 @@ import java.util.Map;
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.amqp.core.MessageDeliveryMode;
 import org.springframework.amqp.core.ReturnedMessage;
@@ -58,6 +60,7 @@ import org.springframework.util.StringUtils;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 4.3
  *
@@ -115,6 +118,8 @@ public abstract class AbstractAmqpOutboundEndpoint extends AbstractReplyProducin
 
 	private volatile ScheduledFuture<?> confirmChecker;
 
+	private final Lock lock = new ReentrantLock();
+
 	/**
 	 * Set a custom {@link AmqpHeaderMapper} for mapping request and reply headers.
 	 * Defaults to {@link DefaultAmqpHeaderMapper#outboundMapper()}.
@@ -336,8 +341,14 @@ public abstract class AbstractAmqpOutboundEndpoint extends AbstractReplyProducin
 		this.confirmTimeout = Duration.ofMillis(confirmTimeout); // NOSONAR sync inconsistency
 	}
 
-	protected final synchronized void setConnectionFactory(ConnectionFactory connectionFactory) {
-		this.connectionFactory = connectionFactory;
+	protected final void setConnectionFactory(ConnectionFactory connectionFactory) {
+		this.lock.lock();
+		try {
+			this.connectionFactory = connectionFactory;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	protected String getExchangeName() {
@@ -487,26 +498,33 @@ public abstract class AbstractAmqpOutboundEndpoint extends AbstractReplyProducin
 	}
 
 	@Override
-	public synchronized void start() {
-		if (!this.running) {
-			if (!this.lazyConnect && this.connectionFactory != null) {
-				try {
-					Connection connection = this.connectionFactory.createConnection(); // NOSONAR (close)
-					if (connection != null) {
-						connection.close();
+	public void start() {
+		this.lock.lock();
+		try {
+			if (!this.running) {
+				if (!this.lazyConnect && this.connectionFactory != null) {
+					try {
+						Connection connection = this.connectionFactory.createConnection(); // NOSONAR (close)
+						if (connection != null) {
+							connection.close();
+						}
+					}
+					catch (RuntimeException ex) {
+						logger.error(ex, "Failed to eagerly establish the connection.");
 					}
 				}
-				catch (RuntimeException ex) {
-					logger.error(ex, "Failed to eagerly establish the connection.");
+				doStart();
+				if (this.confirmTimeout != null && getConfirmNackChannel() != null && getRabbitTemplate() != null) {
+					this.confirmChecker = getTaskScheduler()
+							.scheduleAtFixedRate(checkUnconfirmed(), this.confirmTimeout.dividedBy(2L));
 				}
+				this.running = true;
 			}
-			doStart();
-			if (this.confirmTimeout != null && getConfirmNackChannel() != null && getRabbitTemplate() != null) {
-				this.confirmChecker = getTaskScheduler()
-						.scheduleAtFixedRate(checkUnconfirmed(), this.confirmTimeout.dividedBy(2L));
-			}
-			this.running = true;
 		}
+		finally {
+			this.lock.unlock();
+		}
+
 	}
 
 	private Runnable checkUnconfirmed() {
@@ -526,14 +544,20 @@ public abstract class AbstractAmqpOutboundEndpoint extends AbstractReplyProducin
 	protected abstract RabbitTemplate getRabbitTemplate();
 
 	@Override
-	public synchronized void stop() {
-		if (this.running) {
-			doStop();
+	public void stop() {
+		this.lock.lock();
+		try {
+			if (this.running) {
+				doStop();
+			}
+			this.running = false;
+			if (this.confirmChecker != null) {
+				this.confirmChecker.cancel(false);
+				this.confirmChecker = null;
+			}
 		}
-		this.running = false;
-		if (this.confirmChecker != null) {
-			this.confirmChecker.cancel(false);
-			this.confirmChecker = null;
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-core/src/main/java/org/springframework/integration/channel/AbstractMessageChannel.java

@@ -26,6 +26,8 @@ import java.util.List;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import io.micrometer.observation.ObservationRegistry;
 
@@ -70,6 +72,7 @@ import org.springframework.util.StringUtils;
  * @author Oleg Zhurakousky
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 @IntegrationManagedResource
 public abstract class AbstractMessageChannel extends IntegrationObjectSupport
@@ -475,6 +478,8 @@ public abstract class AbstractMessageChannel extends IntegrationObjectSupport
 	 */
 	protected static class ChannelInterceptorList {
 
+		private final Lock lock = new ReentrantLock();
+
 		protected final List<ChannelInterceptor> interceptors = new CopyOnWriteArrayList<>(); // NOSONAR
 
 		private final LogAccessor logger;
@@ -486,11 +491,15 @@ public abstract class AbstractMessageChannel extends IntegrationObjectSupport
 		}
 
 		public boolean set(List<ChannelInterceptor> interceptors) {
-			synchronized (this.interceptors) {
+			this.lock.lock();
+			try {
 				this.interceptors.clear();
 				this.size = interceptors.size();
 				return this.interceptors.addAll(interceptors);
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 
 		public int getSize() {

spring-integration-core/src/main/java/org/springframework/integration/channel/DefaultHeaderChannelRegistry.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2022 the original author or authors.
+ * Copyright 2013-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,8 @@ import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.integration.context.IntegrationObjectSupport;
 import org.springframework.integration.support.channel.HeaderChannelRegistry;
@@ -44,6 +46,7 @@ import org.springframework.util.Assert;
  * @author Gary Russell
  * @author Artem Bilan
  * @author Trung Pham
+ * @author Christian Tzolov
  *
  * @since 3.0
  *
@@ -69,6 +72,8 @@ public class DefaultHeaderChannelRegistry extends IntegrationObjectSupport
 
 	private volatile boolean explicitlyStopped;
 
+	private final Lock lock = new ReentrantLock();
+
 	/**
 	 * Construct a registry with the default delay for channel expiry.
 	 */
@@ -120,25 +125,37 @@ public class DefaultHeaderChannelRegistry extends IntegrationObjectSupport
 	}
 
 	@Override
-	public synchronized void start() {
-		if (!this.running) {
-			Assert.notNull(getTaskScheduler(), "a task scheduler is required");
-			this.reaperScheduledFuture =
-					getTaskScheduler()
-							.schedule(this, Instant.now().plusMillis(this.reaperDelay));
+	public void start() {
+		this.lock.lock();
+		try {
+			if (!this.running) {
+				Assert.notNull(getTaskScheduler(), "a task scheduler is required");
+				this.reaperScheduledFuture = getTaskScheduler()
+						.schedule(this, Instant.now().plusMillis(this.reaperDelay));
 
-			this.running = true;
+				this.running = true;
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 
 	@Override
-	public synchronized void stop() {
-		this.running = false;
-		if (this.reaperScheduledFuture != null) {
-			this.reaperScheduledFuture.cancel(true);
-			this.reaperScheduledFuture = null;
+	public void stop() {
+		this.lock.lock();
+		try {
+			this.running = false;
+			if (this.reaperScheduledFuture != null) {
+				this.reaperScheduledFuture.cancel(true);
+				this.reaperScheduledFuture = null;
+			}
+			this.explicitlyStopped = true;
 		}
-		this.explicitlyStopped = true;
+		finally {
+			this.lock.unlock();
+		}
+
 	}
 
 	public void stop(Runnable callback) {
@@ -200,35 +217,45 @@ public class DefaultHeaderChannelRegistry extends IntegrationObjectSupport
 	 * Cancel the scheduled reap task and run immediately; then reschedule.
 	 */
 	@Override
-	public synchronized void runReaper() {
-		if (this.reaperScheduledFuture != null) {
-			this.reaperScheduledFuture.cancel(true);
-			this.reaperScheduledFuture = null;
-		}
+	public void runReaper() {
+		this.lock.lock();
+		try {
+			if (this.reaperScheduledFuture != null) {
+				this.reaperScheduledFuture.cancel(true);
+				this.reaperScheduledFuture = null;
+			}
 
-		run();
+			run();
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
-	public synchronized void run() {
-		logger.trace(() -> "Reaper started; channels size=" + this.channels.size());
-		Iterator<Entry<String, MessageChannelWrapper>> iterator = this.channels.entrySet().iterator();
-		long now = System.currentTimeMillis();
-		while (iterator.hasNext()) {
-			Entry<String, MessageChannelWrapper> entry = iterator.next();
-			if (entry.getValue().expireAt() < now) {
-				logger.debug(() -> "Expiring " + entry.getKey() + " (" + entry.getValue().channel() + ")");
-				iterator.remove();
+	public void run() {
+		this.lock.lock();
+		try {
+			logger.trace(() -> "Reaper started; channels size=" + this.channels.size());
+			Iterator<Entry<String, MessageChannelWrapper>> iterator = this.channels.entrySet().iterator();
+			long now = System.currentTimeMillis();
+			while (iterator.hasNext()) {
+				Entry<String, MessageChannelWrapper> entry = iterator.next();
+				if (entry.getValue().expireAt() < now) {
+					logger.debug(() -> "Expiring " + entry.getKey() + " (" + entry.getValue().channel() + ")");
+					iterator.remove();
+				}
 			}
+			this.reaperScheduledFuture = getTaskScheduler()
+					.schedule(this, Instant.now().plusMillis(this.reaperDelay));
+
+			logger.trace(() -> "Reaper completed; channels size=" + this.channels.size());
+		}
+		finally {
+			this.lock.unlock();
 		}
-		this.reaperScheduledFuture =
-				getTaskScheduler()
-						.schedule(this, Instant.now().plusMillis(this.reaperDelay));
-
-		logger.trace(() -> "Reaper completed; channels size=" + this.channels.size());
 	}
 
-
 	protected record MessageChannelWrapper(MessageChannel channel, long expireAt) {
 
 	}

spring-integration-core/src/main/java/org/springframework/integration/config/AbstractSimpleMessageHandlerFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,8 @@
 package org.springframework.integration.config;
 
 import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.aopalliance.aop.Advice;
 import org.apache.commons.logging.Log;
@@ -58,6 +60,7 @@ import org.springframework.util.CollectionUtils;
  * @author Gary Russell
  * @author Artem Bilan
  * @author David Liu
+ * @author Christian Tzolov
  */
 public abstract class AbstractSimpleMessageHandlerFactoryBean<H extends MessageHandler>
 		implements FactoryBean<MessageHandler>, ApplicationContextAware, BeanFactoryAware, BeanNameAware,
@@ -65,7 +68,7 @@ public abstract class AbstractSimpleMessageHandlerFactoryBean<H extends MessageH
 
 	protected final Log logger = LogFactory.getLog(getClass()); //NOSONAR protected with final
 
-	private final Object initializationMonitor = new Object();
+	private final Lock initializationMonitor = new ReentrantLock();
 
 	private BeanFactory beanFactory;
 
@@ -192,7 +195,8 @@ public abstract class AbstractSimpleMessageHandlerFactoryBean<H extends MessageH
 	}
 
 	protected final H createHandlerInternal() {
-		synchronized (this.initializationMonitor) {
+		this.initializationMonitor.lock();
+		try {
 			if (this.initialized) {
 				// There was a problem when this method was called already
 				return null;
@@ -228,6 +232,9 @@ public abstract class AbstractSimpleMessageHandlerFactoryBean<H extends MessageH
 							this.order, theOrder -> ((Orderable) this.handler).setOrder(theOrder));
 			this.initialized = true;
 		}
+		finally {
+			this.initializationMonitor.unlock();
+		}
 		initializingBean();
 		return this.handler;
 	}

spring-integration-core/src/main/java/org/springframework/integration/config/ConsumerEndpointFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,8 @@
 package org.springframework.integration.config;
 
 import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Function;
 
 import org.aopalliance.aop.Advice;
@@ -77,6 +79,7 @@ import org.springframework.util.StringUtils;
  * @author Josh Long
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class ConsumerEndpointFactoryBean
 		implements FactoryBean<AbstractEndpoint>, BeanFactoryAware, BeanNameAware, BeanClassLoaderAware,
@@ -84,9 +87,9 @@ public class ConsumerEndpointFactoryBean
 
 	private static final LogAccessor LOGGER = new LogAccessor(LogFactory.getLog(ConsumerEndpointFactoryBean.class));
 
-	private final Object initializationMonitor = new Object();
+	private final Lock initializationMonitor = new ReentrantLock();
 
-	private final Object handlerMonitor = new Object();
+	private final Lock handlerMonitor = new ReentrantLock();
 
 	private MessageHandler handler;
 
@@ -127,7 +130,8 @@ public class ConsumerEndpointFactoryBean
 	public void setHandler(Object handler) {
 		Assert.isTrue(handler instanceof MessageHandler || handler instanceof ReactiveMessageHandler,
 				"'handler' must be an instance of 'MessageHandler' or 'ReactiveMessageHandler'");
-		synchronized (this.handlerMonitor) {
+		this.handlerMonitor.lock();
+		try {
 			Assert.isNull(this.handler, "handler cannot be overridden");
 			if (handler instanceof ReactiveMessageHandler) {
 				this.handler = new ReactiveMessageHandlerAdapter((ReactiveMessageHandler) handler);
@@ -136,6 +140,9 @@ public class ConsumerEndpointFactoryBean
 				this.handler = (MessageHandler) handler;
 			}
 		}
+		finally {
+			this.handlerMonitor.unlock();
+		}
 	}
 
 	public MessageHandler getHandler() {
@@ -303,7 +310,8 @@ public class ConsumerEndpointFactoryBean
 	}
 
 	private void initializeEndpoint() {
-		synchronized (this.initializationMonitor) {
+		this.initializationMonitor.lock();
+		try {
 			if (this.initialized) {
 				return;
 			}
@@ -340,6 +348,9 @@ public class ConsumerEndpointFactoryBean
 			this.endpoint.afterPropertiesSet();
 			this.initialized = true;
 		}
+		finally {
+			this.initializationMonitor.unlock();
+		}
 	}
 
 	private MessageChannel resolveInputChannel() {

spring-integration-core/src/main/java/org/springframework/integration/config/IdGeneratorConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,8 @@ package org.springframework.integration.config;
 import java.lang.reflect.Field;
 import java.util.HashSet;
 import java.util.Set;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -39,11 +41,14 @@ import org.springframework.util.ReflectionUtils;
  * @author Mark Fisher
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0.4
  */
 public final class IdGeneratorConfigurer implements ApplicationListener<ApplicationContextEvent> {
 
+	private final Lock lock = new ReentrantLock();
+
 	private static final Set<String> GENERATOR_CONTEXT_ID = new HashSet<>();
 
 	private static volatile IdGenerator theIdGenerator;
@@ -51,21 +56,28 @@ public final class IdGeneratorConfigurer implements ApplicationListener<Applicat
 	private final Log logger = LogFactory.getLog(getClass());
 
 	@Override
-	public synchronized void onApplicationEvent(ApplicationContextEvent event) {
-		ApplicationContext context = event.getApplicationContext();
-		if (event instanceof ContextRefreshedEvent) {
-			boolean contextHasIdGenerator = context.getBeanNamesForType(IdGenerator.class).length > 0;
-			if (contextHasIdGenerator && setIdGenerator(context)) {
-				IdGeneratorConfigurer.GENERATOR_CONTEXT_ID.add(context.getId());
+	public void onApplicationEvent(ApplicationContextEvent event) {
+		this.lock.lock();
+		try {
+
+			ApplicationContext context = event.getApplicationContext();
+			if (event instanceof ContextRefreshedEvent) {
+				boolean contextHasIdGenerator = context.getBeanNamesForType(IdGenerator.class).length > 0;
+				if (contextHasIdGenerator && setIdGenerator(context)) {
+					IdGeneratorConfigurer.GENERATOR_CONTEXT_ID.add(context.getId());
+				}
+			}
+			else if (event instanceof ContextClosedEvent
+					&& IdGeneratorConfigurer.GENERATOR_CONTEXT_ID.contains(context.getId())) {
+
+				if (IdGeneratorConfigurer.GENERATOR_CONTEXT_ID.size() == 1) {
+					unsetIdGenerator();
+				}
+				IdGeneratorConfigurer.GENERATOR_CONTEXT_ID.remove(context.getId());
 			}
 		}
-		else if (event instanceof ContextClosedEvent
-				&& IdGeneratorConfigurer.GENERATOR_CONTEXT_ID.contains(context.getId())) {
-
-			if (IdGeneratorConfigurer.GENERATOR_CONTEXT_ID.size() == 1) {
-				unsetIdGenerator();
-			}
-			IdGeneratorConfigurer.GENERATOR_CONTEXT_ID.remove(context.getId());
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-core/src/main/java/org/springframework/integration/config/IdempotentReceiverAutoProxyCreator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,8 @@ import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.aop.Advisor;
 import org.springframework.aop.TargetSource;
@@ -38,6 +40,8 @@ import org.springframework.util.PatternMatchUtils;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
+ *
  * @since 4.1
  */
 @SuppressWarnings("serial")
@@ -47,6 +51,8 @@ class IdempotentReceiverAutoProxyCreator extends AbstractAutoProxyCreator {
 
 	private volatile Map<String, List<String>> idempotentEndpoints; // double check locking requires volatile
 
+	private final Lock lock = new ReentrantLock();
+
 	public void setIdempotentEndpointsMapping(List<Map<String, String>> idempotentEndpointsMapping) {
 		Assert.notEmpty(idempotentEndpointsMapping, "'idempotentEndpointsMapping' must not be empty");
 		this.idempotentEndpointsMapping = idempotentEndpointsMapping; //NOSONAR (inconsistent sync)
@@ -85,8 +91,9 @@ class IdempotentReceiverAutoProxyCreator extends AbstractAutoProxyCreator {
 	}
 
 	private void initIdempotentEndpointsIfNecessary() {
-		if (this.idempotentEndpoints == null) { //NOSONAR (inconsistent sync)
-			synchronized (this) {
+		if (this.idempotentEndpoints == null) { // NOSONAR (inconsistent sync)
+			this.lock.lock();
+			try {
 				if (this.idempotentEndpoints == null) {
 					this.idempotentEndpoints = new LinkedHashMap<String, List<String>>();
 					for (Map<String, String> mapping : this.idempotentEndpointsMapping) {
@@ -104,6 +111,9 @@ class IdempotentReceiverAutoProxyCreator extends AbstractAutoProxyCreator {
 					}
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 	}
 

spring-integration-core/src/main/java/org/springframework/integration/config/SourcePollingChannelAdapterFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,9 @@
 
 package org.springframework.integration.config;
 
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
@@ -41,11 +44,12 @@ import org.springframework.util.StringUtils;
  * @author Oleg Zhurakousky
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class SourcePollingChannelAdapterFactoryBean implements FactoryBean<SourcePollingChannelAdapter>,
 		BeanFactoryAware, BeanNameAware, BeanClassLoaderAware, InitializingBean, SmartLifecycle, DisposableBean {
 
-	private final Object initializationMonitor = new Object();
+	private final Lock initializationMonitor = new ReentrantLock();
 
 	private MessageSource<?> source;
 
@@ -158,7 +162,8 @@ public class SourcePollingChannelAdapterFactoryBean implements FactoryBean<Sourc
 	}
 
 	private void initializeAdapter() {
-		synchronized (this.initializationMonitor) {
+		this.initializationMonitor.lock();
+		try {
 			if (this.initialized) {
 				return;
 			}
@@ -207,6 +212,9 @@ public class SourcePollingChannelAdapterFactoryBean implements FactoryBean<Sourc
 			this.adapter = spca;
 			this.initialized = true;
 		}
+		finally {
+			this.initializationMonitor.unlock();
+		}
 	}
 
 	/*

spring-integration-core/src/main/java/org/springframework/integration/config/xml/SpelPropertyAccessorsParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2019 the original author or authors.
+ * Copyright 2013-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,8 @@
 package org.springframework.integration.config.xml;
 
 import java.util.Map;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
@@ -38,10 +40,14 @@ import org.springframework.util.StringUtils;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
+ *
  * @since 3.0
  */
 public class SpelPropertyAccessorsParser implements BeanDefinitionParser {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Map<String, Object> propertyAccessors = new ManagedMap<String, Object>();
 
 	@Override
@@ -86,17 +92,23 @@ public class SpelPropertyAccessorsParser implements BeanDefinitionParser {
 		return null;
 	}
 
-	private synchronized void initializeSpelPropertyAccessorRegistrarIfNecessary(ParserContext parserContext) {
-		if (!parserContext.getRegistry()
-				.containsBeanDefinition(IntegrationContextUtils.SPEL_PROPERTY_ACCESSOR_REGISTRAR_BEAN_NAME)) {
+	private void initializeSpelPropertyAccessorRegistrarIfNecessary(ParserContext parserContext) {
+		this.lock.lock();
+		try {
+			if (!parserContext.getRegistry()
+					.containsBeanDefinition(IntegrationContextUtils.SPEL_PROPERTY_ACCESSOR_REGISTRAR_BEAN_NAME)) {
 
-			BeanDefinitionBuilder registrarBuilder = BeanDefinitionBuilder
-					.genericBeanDefinition(SpelPropertyAccessorRegistrar.class)
-					.setRole(BeanDefinition.ROLE_INFRASTRUCTURE)
-					.addConstructorArgValue(this.propertyAccessors);
-			parserContext.getRegistry()
-					.registerBeanDefinition(IntegrationContextUtils.SPEL_PROPERTY_ACCESSOR_REGISTRAR_BEAN_NAME,
-							registrarBuilder.getBeanDefinition());
+				BeanDefinitionBuilder registrarBuilder = BeanDefinitionBuilder
+						.genericBeanDefinition(SpelPropertyAccessorRegistrar.class)
+						.setRole(BeanDefinition.ROLE_INFRASTRUCTURE)
+						.addConstructorArgValue(this.propertyAccessors);
+				parserContext.getRegistry()
+						.registerBeanDefinition(IntegrationContextUtils.SPEL_PROPERTY_ACCESSOR_REGISTRAR_BEAN_NAME,
+								registrarBuilder.getBeanDefinition());
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-core/src/main/java/org/springframework/integration/core/MessagingTemplate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,9 @@
 
 package org.springframework.integration.core;
 
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.integration.context.IntegrationContextUtils;
@@ -31,12 +34,15 @@ import org.springframework.messaging.core.GenericMessagingTemplate;
  * @author Oleg Zhurakousky
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 1.0
  *
  */
 public class MessagingTemplate extends GenericMessagingTemplate {
 
+	private final Lock lock = new ReentrantLock();
+
 	private BeanFactory beanFactory;
 
 	private volatile boolean throwExceptionOnLateReplySet;
@@ -84,15 +90,19 @@ public class MessagingTemplate extends GenericMessagingTemplate {
 	@Nullable
 	public Message<?> sendAndReceive(MessageChannel destination, Message<?> requestMessage) {
 		if (!this.throwExceptionOnLateReplySet) {
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				if (!this.throwExceptionOnLateReplySet) {
-					IntegrationProperties integrationProperties =
-							IntegrationContextUtils.getIntegrationProperties(this.beanFactory);
+					IntegrationProperties integrationProperties = IntegrationContextUtils
+							.getIntegrationProperties(this.beanFactory);
 					super.setThrowExceptionOnLateReply(
 							integrationProperties.isMessagingTemplateThrowExceptionOnLateReply());
 					this.throwExceptionOnLateReplySet = true;
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 		return super.sendAndReceive(destination, requestMessage);
 	}

spring-integration-core/src/main/java/org/springframework/integration/dispatcher/AbstractDispatcher.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,8 @@
 package org.springframework.integration.dispatcher;
 
 import java.util.Set;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -41,6 +43,7 @@ import org.springframework.util.Assert;
  * @author Gary Russell
  * @author Diego Belfer
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public abstract class AbstractDispatcher implements MessageDispatcher {
 
@@ -52,6 +55,8 @@ public abstract class AbstractDispatcher implements MessageDispatcher {
 
 	private volatile MessageHandler theOneHandler;
 
+	private final Lock lock = new ReentrantLock();
+
 	/**
 	 * Set the maximum subscribers allowed by this dispatcher.
 	 * @param maxSubscribers The maximum number of subscribers allowed.
@@ -77,17 +82,23 @@ public abstract class AbstractDispatcher implements MessageDispatcher {
 	 * @return the result of {@link Set#add(Object)}
 	 */
 	@Override
-	public synchronized boolean addHandler(MessageHandler handler) {
-		Assert.notNull(handler, "handler must not be null");
-		Assert.isTrue(this.handlers.size() < this.maxSubscribers, "Maximum subscribers exceeded");
-		boolean added = this.handlers.add(handler);
-		if (this.handlers.size() == 1) {
-			this.theOneHandler = handler;
+	public boolean addHandler(MessageHandler handler) {
+		this.lock.lock();
+		try {
+			Assert.notNull(handler, "handler must not be null");
+			Assert.isTrue(this.handlers.size() < this.maxSubscribers, "Maximum subscribers exceeded");
+			boolean added = this.handlers.add(handler);
+			if (this.handlers.size() == 1) {
+				this.theOneHandler = handler;
+			}
+			else {
+				this.theOneHandler = null;
+			}
+			return added;
 		}
-		else {
-			this.theOneHandler = null;
+		finally {
+			this.lock.unlock();
 		}
-		return added;
 	}
 
 	/**
@@ -96,16 +107,22 @@ public abstract class AbstractDispatcher implements MessageDispatcher {
 	 * @return the result of {@link Set#remove(Object)}
 	 */
 	@Override
-	public synchronized boolean removeHandler(MessageHandler handler) {
-		Assert.notNull(handler, "handler must not be null");
-		boolean removed = this.handlers.remove(handler);
-		if (this.handlers.size() == 1) {
-			this.theOneHandler = this.handlers.iterator().next();
+	public boolean removeHandler(MessageHandler handler) {
+		this.lock.lock();
+		try {
+			Assert.notNull(handler, "handler must not be null");
+			boolean removed = this.handlers.remove(handler);
+			if (this.handlers.size() == 1) {
+				this.theOneHandler = this.handlers.iterator().next();
+			}
+			else {
+				this.theOneHandler = null;
+			}
+			return removed;
 		}
-		else {
-			this.theOneHandler = null;
+		finally {
+			this.lock.unlock();
 		}
-		return removed;
 	}
 
 	protected boolean tryOptimizedDispatch(Message<?> message) {

spring-integration-core/src/main/java/org/springframework/integration/dispatcher/PartitionedDispatcher.java

@@ -25,6 +25,8 @@ import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Function;
 
 import org.springframework.integration.util.ErrorHandlingTaskExecutor;
@@ -49,6 +51,7 @@ import org.springframework.util.ErrorHandler;
  * The rest of the logic is similar to {@link UnicastingDispatcher} behavior.
  *
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 6.1
  */
@@ -73,6 +76,8 @@ public class PartitionedDispatcher extends AbstractDispatcher {
 
 	private MessageHandlingTaskDecorator messageHandlingTaskDecorator = task -> task;
 
+	private final Lock lock = new ReentrantLock();
+
 	/**
 	 * Instantiate based on a provided number of partitions and function for partition key against
 	 * the message to dispatch.
@@ -153,7 +158,8 @@ public class PartitionedDispatcher extends AbstractDispatcher {
 
 	private void populatedPartitions() {
 		if (this.partitions.isEmpty()) {
-			synchronized (this.partitions) {
+			this.lock.lock();
+			try {
 				if (this.partitions.isEmpty()) {
 					Map<Integer, UnicastingDispatcher> partitionsToUse = new HashMap<>();
 					for (int i = 0; i < this.partitionCount; i++) {
@@ -162,6 +168,9 @@ public class PartitionedDispatcher extends AbstractDispatcher {
 					this.partitions.putAll(partitionsToUse);
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 	}
 

spring-integration-core/src/main/java/org/springframework/integration/endpoint/AbstractPollingEndpoint.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,8 @@ import java.util.List;
 import java.util.concurrent.Callable;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Collectors;
 
 import org.aopalliance.aop.Advice;
@@ -78,6 +80,7 @@ import org.springframework.util.ReflectionUtils;
  * @author Gary Russell
  * @author Artem Bilan
  * @author Andreas Baer
+ * @author Christian Tzolov
  */
 public abstract class AbstractPollingEndpoint extends AbstractEndpoint implements BeanClassLoaderAware {
 
@@ -88,7 +91,7 @@ public abstract class AbstractPollingEndpoint extends AbstractEndpoint implement
 
 	private final Collection<Advice> appliedAdvices = new HashSet<>();
 
-	private final Object initializationMonitor = new Object();
+	private final Lock initializationMonitor = new ReentrantLock();
 
 	private Executor taskExecutor = new SyncTaskExecutor();
 
@@ -262,7 +265,8 @@ public abstract class AbstractPollingEndpoint extends AbstractEndpoint implement
 
 	@Override
 	protected void onInit() {
-		synchronized (this.initializationMonitor) {
+		this.initializationMonitor.lock();
+		try {
 			if (this.initialized) {
 				return;
 			}
@@ -280,6 +284,9 @@ public abstract class AbstractPollingEndpoint extends AbstractEndpoint implement
 			}
 			this.initialized = true;
 		}
+		finally {
+			this.initializationMonitor.unlock();
+		}
 		try {
 			super.onInit();
 		}

spring-integration-core/src/main/java/org/springframework/integration/endpoint/MethodInvokingMessageSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,8 @@
 package org.springframework.integration.endpoint;
 
 import java.lang.reflect.Method;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.context.Lifecycle;
 import org.springframework.integration.support.management.ManageableLifecycle;
@@ -31,6 +33,7 @@ import org.springframework.util.ReflectionUtils;
  * @author Mark Fisher
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class MethodInvokingMessageSource extends AbstractMessageSource<Object> implements ManageableLifecycle {
 
@@ -42,7 +45,7 @@ public class MethodInvokingMessageSource extends AbstractMessageSource<Object> i
 
 	private volatile boolean initialized;
 
-	private final Object initializationMonitor = new Object();
+	private final Lock initializationMonitor = new ReentrantLock();
 
 
 	public void setObject(Object object) {
@@ -67,7 +70,8 @@ public class MethodInvokingMessageSource extends AbstractMessageSource<Object> i
 
 	@Override
 	protected void onInit() {
-		synchronized (this.initializationMonitor) {
+		this.initializationMonitor.lock();
+		try {
 			if (this.initialized) {
 				return;
 			}
@@ -83,6 +87,9 @@ public class MethodInvokingMessageSource extends AbstractMessageSource<Object> i
 			ReflectionUtils.makeAccessible(this.method);
 			this.initialized = true;
 		}
+		finally {
+			this.initializationMonitor.unlock();
+		}
 	}
 
 	@Override

spring-integration-core/src/main/java/org/springframework/integration/endpoint/SourcePollingChannelAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,9 @@
 
 package org.springframework.integration.endpoint;
 
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
 import org.springframework.aop.framework.Advised;
 import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.context.Lifecycle;
@@ -43,6 +46,7 @@ import org.springframework.util.Assert;
  * @author Oleg Zhurakousky
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class SourcePollingChannelAdapter extends AbstractPollingEndpoint
 		implements TrackableComponent {
@@ -59,6 +63,8 @@ public class SourcePollingChannelAdapter extends AbstractPollingEndpoint
 
 	private volatile boolean shouldTrack;
 
+	private final Lock lock = new ReentrantLock();
+
 	/**
 	 * Specify the source to be polled for Messages.
 	 *
@@ -175,12 +181,16 @@ public class SourcePollingChannelAdapter extends AbstractPollingEndpoint
 
 	public MessageChannel getOutputChannel() {
 		if (this.outputChannelName != null) {
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				if (this.outputChannelName != null) {
 					this.outputChannel = getChannelResolver().resolveDestination(this.outputChannelName);
 					this.outputChannelName = null;
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 		return this.outputChannel;
 	}

spring-integration-core/src/main/java/org/springframework/integration/expression/ReloadableResourceBundleExpressionSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,8 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Properties;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -53,6 +55,7 @@ import org.springframework.util.StringUtils;
  * @author Mark Fisher
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  *
@@ -80,16 +83,22 @@ public class ReloadableResourceBundleExpressionSource implements ExpressionSourc
 	 */
 	private final Map<String, Map<Locale, List<String>>> cachedFilenames = new HashMap<>();
 
+	private final Lock cachedFilenamesMonitor = new ReentrantLock();
+
 	/**
 	 * Cache to hold already loaded properties per filename.
 	 */
 	private final Map<String, PropertiesHolder> cachedProperties = new HashMap<>();
 
+	private final Lock cachedPropertiesMonitor = new ReentrantLock();
+
 	/**
 	 * Cache to hold merged loaded properties per locale.
 	 */
 	private final Map<Locale, PropertiesHolder> cachedMergedProperties = new HashMap<>();
 
+	private final Lock cachedMergedPropertiesMonitor = new ReentrantLock();
+
 	private final ExpressionParser parser = new SpelExpressionParser(new SpelParserConfiguration(true, true));
 
 	private String[] basenames = {};
@@ -282,7 +291,8 @@ public class ReloadableResourceBundleExpressionSource implements ExpressionSourc
 	 * cached forever.
 	 */
 	private PropertiesHolder getMergedProperties(Locale locale) {
-		synchronized (this.cachedMergedProperties) {
+		this.cachedMergedPropertiesMonitor.lock();
+		try {
 			PropertiesHolder mergedHolder = this.cachedMergedProperties.get(locale);
 			if (mergedHolder != null) {
 				return mergedHolder;
@@ -303,6 +313,9 @@ public class ReloadableResourceBundleExpressionSource implements ExpressionSourc
 			this.cachedMergedProperties.put(locale, mergedHolder);
 			return mergedHolder;
 		}
+		finally {
+			this.cachedMergedPropertiesMonitor.unlock();
+		}
 	}
 
 	/**
@@ -316,7 +329,8 @@ public class ReloadableResourceBundleExpressionSource implements ExpressionSourc
 	 * @see #calculateFilenamesForLocale
 	 */
 	private List<String> calculateAllFilenames(String basename, Locale locale) {
-		synchronized (this.cachedFilenames) {
+		this.cachedFilenamesMonitor.lock();
+		try {
 			Map<Locale, List<String>> localeMap = this.cachedFilenames.get(basename);
 			if (localeMap != null) {
 				List<String> filenames = localeMap.get(locale);
@@ -345,6 +359,9 @@ public class ReloadableResourceBundleExpressionSource implements ExpressionSourc
 			}
 			return filenames;
 		}
+		finally {
+			this.cachedFilenamesMonitor.unlock();
+		}
 	}
 
 	/**
@@ -392,7 +409,8 @@ public class ReloadableResourceBundleExpressionSource implements ExpressionSourc
 	 * @return the current PropertiesHolder for the bundle
 	 */
 	private PropertiesHolder getProperties(String filename) {
-		synchronized (this.cachedProperties) {
+		this.cachedPropertiesMonitor.lock();
+		try {
 			PropertiesHolder propHolder = this.cachedProperties.get(filename);
 			if (propHolder != null &&
 					(propHolder.getRefreshTimestamp() < 0 ||
@@ -401,6 +419,9 @@ public class ReloadableResourceBundleExpressionSource implements ExpressionSourc
 			}
 			return refreshProperties(filename, propHolder);
 		}
+		finally {
+			this.cachedPropertiesMonitor.unlock();
+		}
 	}
 
 	/**
@@ -539,12 +560,21 @@ public class ReloadableResourceBundleExpressionSource implements ExpressionSourc
 	 */
 	public void clearCache() {
 		LOGGER.debug("Clearing entire resource bundle cache");
-		synchronized (this.cachedProperties) {
+		this.cachedPropertiesMonitor.lock();
+		try {
 			this.cachedProperties.clear();
 		}
-		synchronized (this.cachedMergedProperties) {
+		finally {
+			this.cachedPropertiesMonitor.unlock();
+		}
+
+		this.cachedMergedPropertiesMonitor.lock();
+		try {
 			this.cachedMergedProperties.clear();
 		}
+		finally {
+			this.cachedMergedPropertiesMonitor.unlock();
+		}
 	}
 
 	@Override

spring-integration-core/src/main/java/org/springframework/integration/gateway/GatewayMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2022 the original author or authors.
+ * Copyright 2016-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,9 @@
 
 package org.springframework.integration.gateway;
 
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
 import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
@@ -28,6 +31,7 @@ import org.springframework.messaging.MessageChannel;
  * The {@link AbstractReplyProducingMessageHandler} implementation for mid-flow Gateway.
  *
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 5.0
  */
@@ -39,6 +43,8 @@ public class GatewayMessageHandler extends AbstractReplyProducingMessageHandler
 
 	private volatile boolean running;
 
+	private final Lock lock = new ReentrantLock();
+
 	public GatewayMessageHandler() {
 		this.gatewayProxyFactoryBean = new GatewayProxyFactoryBean<>();
 	}
@@ -78,11 +84,15 @@ public class GatewayMessageHandler extends AbstractReplyProducingMessageHandler
 	@Override
 	protected Object handleRequestMessage(Message<?> requestMessage) {
 		if (this.exchanger == null) {
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				if (this.exchanger == null) {
 					initialize();
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 		return this.exchanger.exchange(requestMessage);
 	}

spring-integration-core/src/main/java/org/springframework/integration/gateway/GatewayProxyFactoryBean.java

@@ -29,6 +29,8 @@ import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Future;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Supplier;
@@ -106,12 +108,13 @@ import org.springframework.util.StringUtils;
  * @author Gary Russell
  * @author Artem Bilan
  * @author JingPeng Xie
+ * @author Christian Tzolov
  */
 public class GatewayProxyFactoryBean<T> extends AbstractEndpoint
 		implements TrackableComponent, FactoryBean<T>, MethodInterceptor, BeanClassLoaderAware,
 		IntegrationManagement {
 
-	private final Object initializationMonitor = new Object();
+	private final Lock initializationMonitor = new ReentrantLock();
 
 	private final Map<Method, MethodInvocationGateway> gatewayMap = new HashMap<>();
 
@@ -455,7 +458,8 @@ public class GatewayProxyFactoryBean<T> extends AbstractEndpoint
 	@Override
 	@SuppressWarnings("unchecked")
 	protected void onInit() {
-		synchronized (this.initializationMonitor) {
+		this.initializationMonitor.lock();
+		try {
 			if (this.initialized) {
 				return;
 			}
@@ -466,13 +470,15 @@ public class GatewayProxyFactoryBean<T> extends AbstractEndpoint
 
 			populateMethodInvocationGateways();
 
-			ProxyFactory gatewayProxyFactory =
-					new ProxyFactory(this.serviceInterface, this);
+			ProxyFactory gatewayProxyFactory = new ProxyFactory(this.serviceInterface, this);
 			gatewayProxyFactory.addAdvice(new DefaultMethodInvokingMethodInterceptor());
 			this.serviceProxy = (T) gatewayProxyFactory.getProxy(this.beanClassLoader);
 			this.evaluationContext = ExpressionUtils.createStandardEvaluationContext(beanFactory);
 			this.initialized = true;
 		}
+		finally {
+			this.initializationMonitor.unlock();
+		}
 	}
 
 	private void populateMethodInvocationGateways() {

spring-integration-core/src/main/java/org/springframework/integration/gateway/MessagingGatewaySupport.java

@@ -19,6 +19,8 @@ package org.springframework.integration.gateway;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import io.micrometer.observation.ObservationRegistry;
 import org.reactivestreams.Publisher;
@@ -86,6 +88,7 @@ import org.springframework.util.Assert;
  * @author Gary Russell
  * @author Artem Bilan
  * @author Trung Pham
+ * @author Christian Tzolov
  */
 @IntegrationManagedResource
 public abstract class MessagingGatewaySupport extends AbstractEndpoint
@@ -99,7 +102,7 @@ public abstract class MessagingGatewaySupport extends AbstractEndpoint
 	private final HistoryWritingMessagePostProcessor historyWritingPostProcessor =
 			new HistoryWritingMessagePostProcessor();
 
-	private final Object replyMessageCorrelatorMonitor = new Object();
+	private final Lock replyMessageCorrelatorMonitor = new ReentrantLock();
 
 	private final ManagementOverrides managementOverrides = new ManagementOverrides();
 
@@ -892,7 +895,8 @@ public abstract class MessagingGatewaySupport extends AbstractEndpoint
 	protected void registerReplyMessageCorrelatorIfNecessary() {
 		MessageChannel replyChan = getReplyChannel();
 		if (replyChan != null && this.replyMessageCorrelator == null) {
-			synchronized (this.replyMessageCorrelatorMonitor) {
+			this.replyMessageCorrelatorMonitor.lock();
+			try {
 				if (this.replyMessageCorrelator != null) {
 					return;
 				}
@@ -923,6 +927,9 @@ public abstract class MessagingGatewaySupport extends AbstractEndpoint
 				correlator.afterPropertiesSet();
 				this.replyMessageCorrelator = correlator;
 			}
+			finally {
+				this.replyMessageCorrelatorMonitor.unlock();
+			}
 			if (isRunning()) {
 				this.replyMessageCorrelator.start();
 			}

spring-integration-core/src/main/java/org/springframework/integration/graph/IntegrationGraphServer.java

@@ -26,6 +26,8 @@ import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Objects;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -61,6 +63,7 @@ import org.springframework.messaging.PollableChannel;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 4.3
  *
@@ -70,6 +73,8 @@ public class IntegrationGraphServer implements ApplicationContextAware, Applicat
 
 	private static final float GRAPH_VERSION = 1.2f;
 
+	private final Lock lock = new ReentrantLock();
+
 	private final NodeFactory nodeFactory = new NodeFactory(this::enhance);
 
 	private MicrometerNodeEnhancer micrometerEnhancer;
@@ -127,12 +132,16 @@ public class IntegrationGraphServer implements ApplicationContextAware, Applicat
 	 * @see #rebuild()
 	 */
 	public Graph getGraph() {
-		if (this.graph == null) { //NOSONAR (sync)
-			synchronized (this) {
+		if (this.graph == null) { // NOSONAR (sync)
+			this.lock.lock();
+			try {
 				if (this.graph == null) {
 					buildGraph();
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 		return this.graph;
 	}
@@ -169,35 +178,41 @@ public class IntegrationGraphServer implements ApplicationContextAware, Applicat
 		}
 	}
 
-	private synchronized Graph buildGraph() {
-		if (this.micrometerEnhancer == null && MicrometerMetricsCaptorConfiguration.METER_REGISTRY_PRESENT) {
-			this.micrometerEnhancer = new MicrometerNodeEnhancer(this.applicationContext);
+	private Graph buildGraph() {
+		this.lock.lock();
+		try {
+			if (this.micrometerEnhancer == null && MicrometerMetricsCaptorConfiguration.METER_REGISTRY_PRESENT) {
+				this.micrometerEnhancer = new MicrometerNodeEnhancer(this.applicationContext);
+			}
+			String implementationVersion = IntegrationGraphServer.class.getPackage().getImplementationVersion();
+			if (implementationVersion == null) {
+				implementationVersion = "unknown - is Spring Integration running from the distribution jar?";
+			}
+			Map<String, Object> descriptor = new HashMap<>();
+			descriptor.put("provider", "spring-integration");
+			descriptor.put("providerVersion", implementationVersion);
+			descriptor.put("providerFormatVersion", GRAPH_VERSION);
+			String name = this.applicationName;
+			if (name == null) {
+				name = this.applicationContext.getEnvironment().getProperty("spring.application.name");
+			}
+			if (name != null) {
+				descriptor.put("name", name);
+			}
+			this.nodeFactory.reset();
+			Collection<IntegrationNode> nodes = new ArrayList<>();
+			Collection<LinkNode> links = new ArrayList<>();
+			Map<String, MessageChannelNode> channelNodes = channels(nodes);
+			pollingAdapters(nodes, links, channelNodes);
+			gateways(nodes, links, channelNodes);
+			producers(nodes, links, channelNodes);
+			consumers(nodes, links, channelNodes);
+			this.graph = new Graph(descriptor, nodes, links);
+			return this.graph;
 		}
-		String implementationVersion = IntegrationGraphServer.class.getPackage().getImplementationVersion();
-		if (implementationVersion == null) {
-			implementationVersion = "unknown - is Spring Integration running from the distribution jar?";
+		finally {
+			this.lock.unlock();
 		}
-		Map<String, Object> descriptor = new HashMap<>();
-		descriptor.put("provider", "spring-integration");
-		descriptor.put("providerVersion", implementationVersion);
-		descriptor.put("providerFormatVersion", GRAPH_VERSION);
-		String name = this.applicationName;
-		if (name == null) {
-			name = this.applicationContext.getEnvironment().getProperty("spring.application.name");
-		}
-		if (name != null) {
-			descriptor.put("name", name);
-		}
-		this.nodeFactory.reset();
-		Collection<IntegrationNode> nodes = new ArrayList<>();
-		Collection<LinkNode> links = new ArrayList<>();
-		Map<String, MessageChannelNode> channelNodes = channels(nodes);
-		pollingAdapters(nodes, links, channelNodes);
-		gateways(nodes, links, channelNodes);
-		producers(nodes, links, channelNodes);
-		consumers(nodes, links, channelNodes);
-		this.graph = new Graph(descriptor, nodes, links);
-		return this.graph;
 	}
 
 	private Map<String, MessageChannelNode> channels(Collection<IntegrationNode> nodes) {

spring-integration-core/src/main/java/org/springframework/integration/handler/AbstractReplyProducingMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@ package org.springframework.integration.handler;
 
 import java.util.LinkedList;
 import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.aopalliance.aop.Advice;
 
@@ -41,10 +43,13 @@ import org.springframework.util.ClassUtils;
  * @author Artem Bilan
  * @author David Liu
  * @author Trung Pham
+ * @author Christian Tzolov
  */
 public abstract class AbstractReplyProducingMessageHandler extends AbstractMessageProducingHandler
 		implements BeanClassLoaderAware {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final List<Advice> adviceChain = new LinkedList<>();
 
 	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
@@ -72,13 +77,17 @@ public abstract class AbstractReplyProducingMessageHandler extends AbstractMessa
 	 */
 	public void setAdviceChain(List<Advice> adviceChain) {
 		Assert.notEmpty(adviceChain, "adviceChain cannot be empty");
-		synchronized (this.adviceChain) {
+		this.lock.lock();
+		try {
 			this.adviceChain.clear();
 			this.adviceChain.addAll(adviceChain);
 			if (isInitialized()) {
 				initAdvisedRequestHandlerIfAny();
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	protected boolean hasAdviceChain() {

spring-integration-core/src/main/java/org/springframework/integration/handler/DelayHandler.java

@@ -98,6 +98,7 @@ import org.springframework.util.ObjectUtils;
  * @author Mark Fisher
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
  *
  * @since 1.0.3
  */
@@ -110,6 +111,8 @@ public class DelayHandler extends AbstractReplyProducingMessageHandler implement
 
 	public static final long DEFAULT_RETRY_DELAY = 1_000;
 
+	private final Lock lock = new ReentrantLock();
+
 	private final ConcurrentMap<String, AtomicInteger> deliveries = new ConcurrentHashMap<>();
 
 	private final Lock removeReleasedMessageLock = new ReentrantLock();
@@ -618,22 +621,28 @@ public class DelayHandler extends AbstractReplyProducingMessageHandler implement
 	 * behavior is dictated by the avoidance of invocation thread overload.
 	 */
 	@Override
-	public synchronized void reschedulePersistedMessages() {
-		MessageGroup messageGroup = this.messageStore.getMessageGroup(this.messageGroupId);
-		try (Stream<Message<?>> messageStream = messageGroup.streamMessages()) {
-			TaskScheduler taskScheduler = getTaskScheduler();
-			messageStream.forEach((message) -> // NOSONAR
-					taskScheduler.schedule(() -> {
-						// This is fine to keep the reference to the message,
-						// because the scheduled task is performed immediately.
-						long delay = determineDelayForMessage(message);
-						if (delay > 0) {
-							releaseMessageAfterDelay(message, delay);
-						}
-						else {
-							releaseMessage(message);
-						}
-					}, Instant.now()));
+	public void reschedulePersistedMessages() {
+		this.lock.lock();
+		try {
+			MessageGroup messageGroup = this.messageStore.getMessageGroup(this.messageGroupId);
+			try (Stream<Message<?>> messageStream = messageGroup.streamMessages()) {
+				TaskScheduler taskScheduler = getTaskScheduler();
+				messageStream.forEach((message) -> // NOSONAR
+				taskScheduler.schedule(() -> {
+					// This is fine to keep the reference to the message,
+					// because the scheduled task is performed immediately.
+					long delay = determineDelayForMessage(message);
+					if (delay > 0) {
+						releaseMessageAfterDelay(message, delay);
+					}
+					else {
+						releaseMessage(message);
+					}
+				}, Instant.now()));
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-core/src/main/java/org/springframework/integration/handler/MessageHandlerChain.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.context.Lifecycle;
@@ -66,11 +67,12 @@ import org.springframework.util.Assert;
  * @author Gary Russell
  * @author Artem Bilan
  * @author Trung Pham
+ * @author Christian Tzolov
  */
 public class MessageHandlerChain extends AbstractMessageProducingHandler
 		implements CompositeMessageHandler, ManageableLifecycle {
 
-	private final Object initializationMonitor = new Object();
+	private final Lock initializationMonitor = new ReentrantLock();
 
 	private final ReentrantLock lifecycleLock = new ReentrantLock();
 
@@ -102,13 +104,17 @@ public class MessageHandlerChain extends AbstractMessageProducingHandler
 	@Override
 	protected void onInit() {
 		super.onInit();
-		synchronized (this.initializationMonitor) {
+		this.initializationMonitor.lock();
+		try {
 			if (!this.initialized) {
 				Assert.notEmpty(this.handlers, "handler list must not be empty");
 				configureChain();
 				this.initialized = true;
 			}
 		}
+		finally {
+			this.initializationMonitor.unlock();
+		}
 	}
 
 	private void configureChain() {

spring-integration-core/src/main/java/org/springframework/integration/handler/support/MessagingMethodInvokerHelper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,6 +34,8 @@ import java.util.Optional;
 import java.util.Properties;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
@@ -119,6 +121,8 @@ import org.springframework.util.StringUtils;
  * @author Gary Russell
  * @author Artem Bilan
  * @author Trung Pham
+ * @author Christian Tzolov
+ *
  * @since 2.0
  */
 public class MessagingMethodInvokerHelper extends AbstractExpressionEvaluator implements ManageableLifecycle {
@@ -160,6 +164,8 @@ public class MessagingMethodInvokerHelper extends AbstractExpressionEvaluator im
 		SPEL_COMPILERS.put(SpelCompilerMode.MIXED, EXPRESSION_PARSER_MIXED);
 	}
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Object targetObject;
 
 	private final JsonObjectMapper<?, ?> jsonObjectMapper;
@@ -486,23 +492,28 @@ public class MessagingMethodInvokerHelper extends AbstractExpressionEvaluator im
 		}
 	}
 
-	private synchronized void initialize() {
-		if (isProvidedMessageHandlerFactoryBean()) {
-			LOGGER.trace("Overriding default instance of MessageHandlerMethodFactory with the one provided.");
-			this.messageHandlerMethodFactory =
-					getBeanFactory()
-							.getBean(
-									this.canProcessMessageList
-											? IntegrationContextUtils.LIST_MESSAGE_HANDLER_FACTORY_BEAN_NAME
-											: IntegrationContextUtils.MESSAGE_HANDLER_FACTORY_BEAN_NAME,
-									MessageHandlerMethodFactory.class);
-		}
-		else {
-			configureLocalMessageHandlerFactory();
-		}
+	private void initialize() {
+		this.lock.lock();
+		try {
+			if (isProvidedMessageHandlerFactoryBean()) {
+				LOGGER.trace("Overriding default instance of MessageHandlerMethodFactory with the one provided.");
+				this.messageHandlerMethodFactory = getBeanFactory()
+						.getBean(
+								this.canProcessMessageList
+										? IntegrationContextUtils.LIST_MESSAGE_HANDLER_FACTORY_BEAN_NAME
+										: IntegrationContextUtils.MESSAGE_HANDLER_FACTORY_BEAN_NAME,
+								MessageHandlerMethodFactory.class);
+			}
+			else {
+				configureLocalMessageHandlerFactory();
+			}
 
-		prepareEvaluationContext();
-		this.initialized = true;
+			prepareEvaluationContext();
+			this.initialized = true;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	private boolean isProvidedMessageHandlerFactoryBean() {

spring-integration-core/src/main/java/org/springframework/integration/history/MessageHistoryConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,8 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -44,6 +46,7 @@ import org.springframework.util.StringUtils;
  * @author Mark Fisher
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
@@ -54,6 +57,8 @@ public class MessageHistoryConfigurer implements ManageableSmartLifecycle, BeanF
 
 	private static final Log LOGGER = LogFactory.getLog(MessageHistoryConfigurer.class);
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Set<TrackableComponent> currentlyTrackedComponents = ConcurrentHashMap.newKeySet();
 
 	private String[] componentNamePatterns = {"*"};
@@ -180,7 +185,8 @@ public class MessageHistoryConfigurer implements ManageableSmartLifecycle, BeanF
 	@ManagedOperation
 	@Override
 	public void start() {
-		synchronized (this.currentlyTrackedComponents) {
+		this.lock.lock();
+		try {
 			if (!this.running) {
 				for (TrackableComponent component : getTrackableComponents(this.beanFactory)) {
 					trackComponentIfAny(component);
@@ -188,12 +194,16 @@ public class MessageHistoryConfigurer implements ManageableSmartLifecycle, BeanF
 				}
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@ManagedOperation
 	@Override
 	public void stop() {
-		synchronized (this.currentlyTrackedComponents) {
+		this.lock.lock();
+		try {
 			if (this.running) {
 				this.currentlyTrackedComponents.forEach(component -> {
 					component.setShouldTrack(false);
@@ -207,6 +217,9 @@ public class MessageHistoryConfigurer implements ManageableSmartLifecycle, BeanF
 				this.running = false;
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	private static Collection<TrackableComponent> getTrackableComponents(ListableBeanFactory beanFactory) {

spring-integration-core/src/main/java/org/springframework/integration/router/AbstractMessageRouter.java

@@ -18,6 +18,8 @@ package org.springframework.integration.router;
 
 import java.util.Collection;
 import java.util.UUID;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.core.convert.ConversionService;
@@ -43,11 +45,14 @@ import org.springframework.util.Assert;
  * @author Soby Chacko
  * @author Stefan Ferstl
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 @ManagedResource
 @IntegrationManagedResource
 public abstract class AbstractMessageRouter extends AbstractMessageHandler implements MessageRouter {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final MessagingTemplate messagingTemplate = new MessagingTemplate();
 
 	private volatile MessageChannel defaultOutputChannel;
@@ -83,12 +88,16 @@ public abstract class AbstractMessageRouter extends AbstractMessageHandler imple
 	@Override
 	public MessageChannel getDefaultOutputChannel() {
 		if (this.defaultOutputChannelName != null) {
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				if (this.defaultOutputChannelName != null) {
 					this.defaultOutputChannel = getChannelResolver().resolveDestination(this.defaultOutputChannelName);
 					this.defaultOutputChannelName = null;
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 		return this.defaultOutputChannel;
 	}

spring-integration-core/src/main/java/org/springframework/integration/selector/MessageSelectorChain.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@ package org.springframework.integration.selector;
 
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.integration.core.MessageSelector;
 import org.springframework.messaging.Message;
@@ -32,9 +34,12 @@ import org.springframework.util.Assert;
  * @author Mark Fisher
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class MessageSelectorChain implements MessageSelector {
 
+	private final Lock lock = new ReentrantLock();
+
 	private volatile VotingStrategy votingStrategy = VotingStrategy.ALL;
 
 	private final List<MessageSelector> selectors = new CopyOnWriteArrayList<>();
@@ -72,10 +77,14 @@ public class MessageSelectorChain implements MessageSelector {
 	 */
 	public void setSelectors(List<MessageSelector> selectors) {
 		Assert.notEmpty(selectors, "selectors must not be empty");
-		synchronized (this.selectors) {
+		this.lock.lock();
+		try {
 			this.selectors.clear();
 			this.selectors.addAll(selectors);
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	/**

spring-integration-core/src/main/java/org/springframework/integration/selector/MetadataStoreSelector.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2020 the original author or authors.
+ * Copyright 2014-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
 
 package org.springframework.integration.selector;
 
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.BiPredicate;
 
 import org.springframework.integration.core.MessageSelector;
@@ -50,11 +52,14 @@ import org.springframework.util.Assert;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
  *
  * @since 4.1
  */
 public class MetadataStoreSelector implements MessageSelector {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final ConcurrentMetadataStore metadataStore;
 
 	private final MessageProcessor<String> keyStrategy;
@@ -119,7 +124,8 @@ public class MetadataStoreSelector implements MessageSelector {
 			return this.metadataStore.putIfAbsent(key, value) == null;
 		}
 		else {
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				String oldValue = this.metadataStore.get(key);
 				if (oldValue == null) {
 					return this.metadataStore.putIfAbsent(key, value) == null;
@@ -129,6 +135,9 @@ public class MetadataStoreSelector implements MessageSelector {
 				}
 				return false;
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 	}
 

spring-integration-core/src/main/java/org/springframework/integration/store/AbstractMessageGroupStore.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,8 @@ package org.springframework.integration.store;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.LinkedHashSet;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -33,6 +35,7 @@ import org.springframework.messaging.Message;
  * @author Oleg Zhurakousky
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
@@ -42,6 +45,8 @@ public abstract class AbstractMessageGroupStore extends AbstractBatchingMessageG
 
 	protected final Log logger = LogFactory.getLog(getClass()); // NOSONAR final
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Collection<MessageGroupCallback> expiryCallbacks = new LinkedHashSet<>();
 
 	private final MessageGroupFactory persistentMessageGroupFactory =
@@ -122,22 +127,28 @@ public abstract class AbstractMessageGroupStore extends AbstractBatchingMessageG
 
 	@Override
 	@ManagedOperation
-	public synchronized int expireMessageGroups(long timeout) {
-		int count = 0;
-		long threshold = System.currentTimeMillis() - timeout;
-		for (MessageGroup group : this) {
+	public int expireMessageGroups(long timeout) {
+		this.lock.lock();
+		try {
+			int count = 0;
+			long threshold = System.currentTimeMillis() - timeout;
+			for (MessageGroup group : this) {
 
-			long timestamp = group.getTimestamp();
-			if (this.isTimeoutOnIdle() && group.getLastModified() > 0) {
-				timestamp = group.getLastModified();
-			}
+				long timestamp = group.getTimestamp();
+				if (this.isTimeoutOnIdle() && group.getLastModified() > 0) {
+					timestamp = group.getLastModified();
+				}
 
-			if (timestamp <= threshold) {
-				count++;
-				expire(copy(group));
+				if (timestamp <= threshold) {
+					count++;
+					expire(copy(group));
+				}
 			}
+			return count;
+		}
+		finally {
+			this.lock.unlock();
 		}
-		return count;
 	}
 
 	/**

spring-integration-core/src/main/java/org/springframework/integration/store/PersistentMessageGroup.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 the original author or authors.
+ * Copyright 2016-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.Spliterator;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Stream;
 
 import org.apache.commons.logging.Log;
@@ -32,6 +34,7 @@ import org.springframework.messaging.Message;
 
 /**
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 4.3
  */
@@ -39,6 +42,8 @@ class PersistentMessageGroup implements MessageGroup {
 
 	private static final Log LOGGER = LogFactory.getLog(PersistentMessageGroup.class);
 
+	private final Lock lock = new ReentrantLock();
+
 	private final MessageGroupStore messageGroupStore;
 
 	private final Collection<Message<?>> messages = new PersistentCollection();
@@ -76,7 +81,8 @@ class PersistentMessageGroup implements MessageGroup {
 	@Override
 	public Message<?> getOne() {
 		if (this.oneMessage == null) {
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				if (this.oneMessage == null) {
 					if (LOGGER.isDebugEnabled()) {
 						LOGGER.debug("Lazy loading of one message for messageGroup: " + this.original.getGroupId());
@@ -84,6 +90,9 @@ class PersistentMessageGroup implements MessageGroup {
 					this.oneMessage = this.messageGroupStore.getOneMessageFromGroup(this.original.getGroupId());
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 		return this.oneMessage;
 	}
@@ -109,7 +118,8 @@ class PersistentMessageGroup implements MessageGroup {
 	@Override
 	public int size() {
 		if (this.size == 0) {
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				if (this.size == 0) {
 					if (LOGGER.isDebugEnabled()) {
 						LOGGER.debug("Lazy loading of group size for messageGroup: " + this.original.getGroupId());
@@ -117,6 +127,9 @@ class PersistentMessageGroup implements MessageGroup {
 					this.size = this.messageGroupStore.messageGroupSize(this.original.getGroupId());
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 		return this.size;
 	}
@@ -195,6 +208,8 @@ class PersistentMessageGroup implements MessageGroup {
 
 	private final class PersistentCollection extends AbstractCollection<Message<?>> {
 
+		private final Lock innerLock = new ReentrantLock();
+
 		private volatile Collection<Message<?>> collection;
 
 		PersistentCollection() {
@@ -202,7 +217,8 @@ class PersistentMessageGroup implements MessageGroup {
 
 		private void load() {
 			if (this.collection == null) {
-				synchronized (this) {
+				this.innerLock.lock();
+				try {
 					if (this.collection == null) {
 						Object groupId = PersistentMessageGroup.this.original.getGroupId();
 						if (LOGGER.isDebugEnabled()) {
@@ -211,6 +227,9 @@ class PersistentMessageGroup implements MessageGroup {
 						this.collection = PersistentMessageGroup.this.messageGroupStore.getMessagesForGroup(groupId);
 					}
 				}
+				finally {
+					this.innerLock.unlock();
+				}
 			}
 		}
 

spring-integration-core/src/main/java/org/springframework/integration/store/SimpleMessageGroup.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,8 @@ import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.Set;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.integration.IntegrationMessageHeaderAccessor;
 import org.springframework.lang.Nullable;
@@ -38,11 +40,14 @@ import org.springframework.util.Assert;
  * @author Dave Syer
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
 public class SimpleMessageGroup implements MessageGroup {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Object groupId;
 
 	private final Collection<Message<?>> messages;
@@ -189,10 +194,14 @@ public class SimpleMessageGroup implements MessageGroup {
 
 	@Override
 	public Message<?> getOne() {
-		synchronized (this.messages) {
+		this.lock.lock();
+		try {
 			Iterator<Message<?>> iterator = this.messages.iterator();
 			return iterator.hasNext() ? iterator.next() : null;
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override

spring-integration-core/src/main/java/org/springframework/integration/support/SmartLifecycleRoleController.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2021 the original author or authors.
+ * Copyright 2015-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,8 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
@@ -52,6 +54,7 @@ import org.springframework.util.MultiValueMap;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 4.2
  *
@@ -63,6 +66,8 @@ public class SmartLifecycleRoleController implements ApplicationListener<Abstrac
 
 	private static final String IN_ROLE = " in role ";
 
+	private final Lock lock = new ReentrantLock();
+
 	private final MultiValueMap<String, SmartLifecycle> lifecycles = new LinkedMultiValueMap<>();
 
 	private final MultiValueMap<String, String> lazyLifecycles = new LinkedMultiValueMap<>();
@@ -283,9 +288,15 @@ public class SmartLifecycleRoleController implements ApplicationListener<Abstrac
 						Lifecycle::isRunning));
 	}
 
-	private synchronized void addLazyLifecycles() {
-		this.lazyLifecycles.forEach(this::doAddLifecyclesToRole);
-		this.lazyLifecycles.clear();
+	private void addLazyLifecycles() {
+		this.lock.lock();
+		try {
+			this.lazyLifecycles.forEach(this::doAddLifecyclesToRole);
+			this.lazyLifecycles.clear();
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	private void doAddLifecyclesToRole(String role, List<String> lifecycleBeanNames) {

spring-integration-core/src/main/java/org/springframework/integration/support/channel/BeanFactoryChannelResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,9 @@
 
 package org.springframework.integration.support.channel;
 
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
@@ -39,6 +42,7 @@ import org.springframework.util.Assert;
  * @author Mark Fisher
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @see BeanFactory
  */
@@ -46,6 +50,8 @@ public class BeanFactoryChannelResolver implements DestinationResolver<MessageCh
 
 	private static final Log LOGGER = LogFactory.getLog(BeanFactoryChannelResolver.class);
 
+	private final Lock lock = new ReentrantLock();
+
 	private BeanFactory beanFactory;
 
 	private HeaderChannelRegistry replyChannelRegistry;
@@ -93,12 +99,12 @@ public class BeanFactoryChannelResolver implements DestinationResolver<MessageCh
 						+ name + "' exists, but failed to be created", e);
 			}
 			if (!this.initialized) {
-				synchronized (this) {
+				this.lock.lock();
+				try {
 					if (!this.initialized) {
 						try {
-							this.replyChannelRegistry =
-									this.beanFactory.getBean("integrationHeaderChannelRegistry",
-											HeaderChannelRegistry.class);
+							this.replyChannelRegistry = this.beanFactory.getBean("integrationHeaderChannelRegistry",
+									HeaderChannelRegistry.class);
 						}
 						catch (Exception ex) {
 							LOGGER.debug("No HeaderChannelRegistry found");
@@ -106,6 +112,9 @@ public class BeanFactoryChannelResolver implements DestinationResolver<MessageCh
 						this.initialized = true;
 					}
 				}
+				finally {
+					this.lock.unlock();
+				}
 			}
 			if (this.replyChannelRegistry != null) {
 				MessageChannel channel = this.replyChannelRegistry.channelNameToChannel(name);

spring-integration-core/src/main/java/org/springframework/integration/support/leader/LockRegistryLeaderInitiator.java

@@ -21,6 +21,7 @@ import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.context.ApplicationEventPublisher;
@@ -56,6 +57,7 @@ import org.springframework.util.Assert;
  * @author Glenn Renfro
  * @author Kiel Boatman
  * @author Gary Russell
+ * @author Christian Tzolov
  *
  * @since 4.3.1
  */
@@ -68,6 +70,8 @@ public class LockRegistryLeaderInitiator implements SmartLifecycle, DisposableBe
 
 	private static final LogAccessor LOGGER = new LogAccessor(LockRegistryLeaderInitiator.class);
 
+	private final Lock lock = new ReentrantLock();
+
 	/**
 	 * A lock registry. The locks it manages should be global (whatever that means for the
 	 * system) and expiring, in case the holder dies without notifying anyone.
@@ -286,15 +290,21 @@ public class LockRegistryLeaderInitiator implements SmartLifecycle, DisposableBe
 	 * Start the registration of the {@link #candidate} for leader election.
 	 */
 	@Override
-	public synchronized void start() {
-		if (this.leaderEventPublisher == null && this.applicationEventPublisher != null) {
-			this.leaderEventPublisher = new DefaultLeaderEventPublisher(this.applicationEventPublisher);
+	public void start() {
+		this.lock.lock();
+		try {
+			if (this.leaderEventPublisher == null && this.applicationEventPublisher != null) {
+				this.leaderEventPublisher = new DefaultLeaderEventPublisher(this.applicationEventPublisher);
+			}
+			if (!this.running) {
+				this.leaderSelector = new LeaderSelector(buildLeaderPath());
+				this.running = true;
+				this.future = this.taskExecutor.submit(this.leaderSelector);
+				LOGGER.debug("Started LeaderInitiator");
+			}
 		}
-		if (!this.running) {
-			this.leaderSelector = new LeaderSelector(buildLeaderPath());
-			this.running = true;
-			this.future = this.taskExecutor.submit(this.leaderSelector);
-			LOGGER.debug("Started LeaderInitiator");
+		finally {
+			this.lock.unlock();
 		}
 	}
 
@@ -308,14 +318,20 @@ public class LockRegistryLeaderInitiator implements SmartLifecycle, DisposableBe
 	 * candidate is currently leader, its leadership will be revoked.
 	 */
 	@Override
-	public synchronized void stop() {
-		if (this.running) {
-			this.running = false;
-			if (this.future != null) {
-				this.future.cancel(true);
+	public void stop() {
+		this.lock.lock();
+		try {
+			if (this.running) {
+				this.running = false;
+				if (this.future != null) {
+					this.future.cancel(true);
+				}
+				this.future = null;
+				LOGGER.debug(() -> "Stopped LeaderInitiator for " + getContext());
 			}
-			this.future = null;
-			LOGGER.debug(() -> "Stopped LeaderInitiator for " + getContext());
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-core/src/main/java/org/springframework/integration/transformer/support/RoutingSlipHeaderValueMessageProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanFactory;
@@ -41,12 +43,16 @@ import org.springframework.util.Assert;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
+ *
  * @since 4.1
  */
 public class RoutingSlipHeaderValueMessageProcessor
 		extends AbstractHeaderValueMessageProcessor<Map<List<Object>, Integer>>
 		implements BeanFactoryAware {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final List<Object> routingSlipPath;
 
 	private volatile Map<List<Object>, Integer> routingSlip;
@@ -79,7 +85,8 @@ public class RoutingSlipHeaderValueMessageProcessor
 		// use a local variable to avoid the second access to volatile field on the happy path
 		Map<List<Object>, Integer> slip = this.routingSlip;
 		if (slip == null) {
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				slip = this.routingSlip;
 				if (slip == null) {
 					List<Object> slipPath = this.routingSlipPath;
@@ -118,6 +125,9 @@ public class RoutingSlipHeaderValueMessageProcessor
 					this.routingSlip = slip;
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 		return slip;
 	}

spring-integration-core/src/main/java/org/springframework/integration/util/AcceptOnceCollectionFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,8 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 /**
  * An implementation of {@link CollectionFilter} that remembers the elements passed in
@@ -28,6 +30,7 @@ import java.util.List;
  * @param <T> the collection element type.
  *
  * @author Mark Fisher
+ * @author Christian Tzolov
  *
  * @since 2.1
  */
@@ -35,15 +38,23 @@ public class AcceptOnceCollectionFilter<T> implements CollectionFilter<T> {
 
 	private volatile Collection<T> lastSeenElements = Collections.emptyList();
 
-	public synchronized Collection<T> filter(Collection<T> unfilteredElements) {
-		List<T> filteredElements = new ArrayList<>();
-		for (T element : unfilteredElements) {
-			if (!this.lastSeenElements.contains(element)) {
-				filteredElements.add(element);
+	private final Lock lock = new ReentrantLock();
+
+	public Collection<T> filter(Collection<T> unfilteredElements) {
+		this.lock.lock();
+		try {
+			List<T> filteredElements = new ArrayList<>();
+			for (T element : unfilteredElements) {
+				if (!this.lastSeenElements.contains(element)) {
+					filteredElements.add(element);
+				}
 			}
+			this.lastSeenElements = unfilteredElements;
+			return filteredElements;
+		}
+		finally {
+			this.lock.unlock();
 		}
-		this.lastSeenElements = unfilteredElements;
-		return filteredElements;
 	}
 
 }

spring-integration-core/src/main/java/org/springframework/integration/util/SimplePool.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,8 @@ import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -40,6 +42,7 @@ import org.springframework.util.Assert;
  * @author Gary Russell
  * @author Sergey Bogatyrev
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.2
  *
@@ -48,6 +51,8 @@ public class SimplePool<T> implements Pool<T> {
 
 	protected final Log logger = LogFactory.getLog(getClass()); // NOSONAR final
 
+	private final Lock lock = new ReentrantLock();
+
 	private final PoolSemaphore permits = new PoolSemaphore(0);
 
 	private final AtomicInteger poolSize = new AtomicInteger();
@@ -93,39 +98,45 @@ public class SimplePool<T> implements Pool<T> {
 	 * items are returned.
 	 * @param poolSize The desired target pool size.
 	 */
-	public synchronized void setPoolSize(int poolSize) {
-		int delta = poolSize - this.poolSize.get();
-		this.targetPoolSize.addAndGet(delta);
-		if (this.logger.isDebugEnabled()) {
-			this.logger.debug(String.format("Target pool size changed by %d, now %d", delta,
-					this.targetPoolSize.get()));
-		}
-		if (delta > 0) {
-			this.poolSize.addAndGet(delta);
-			this.permits.release(delta);
-		}
-		else {
-			this.permits.reducePermits(-delta);
+	public void setPoolSize(int poolSize) {
+		this.lock.lock();
+		try {
+			int delta = poolSize - this.poolSize.get();
+			this.targetPoolSize.addAndGet(delta);
+			if (this.logger.isDebugEnabled()) {
+				this.logger.debug(String.format("Target pool size changed by %d, now %d", delta,
+						this.targetPoolSize.get()));
+			}
+			if (delta > 0) {
+				this.poolSize.addAndGet(delta);
+				this.permits.release(delta);
+			}
+			else {
+				this.permits.reducePermits(-delta);
 
-			int inUseSize = this.inUse.size();
-			int newPoolSize = Math.max(poolSize, inUseSize);
-			this.poolSize.set(newPoolSize);
+				int inUseSize = this.inUse.size();
+				int newPoolSize = Math.max(poolSize, inUseSize);
+				this.poolSize.set(newPoolSize);
 
-			for (int i = this.available.size(); i > newPoolSize - inUseSize; i--) {
-				T item = this.available.poll();
-				if (item != null) {
-					doRemoveItem(item);
+				for (int i = this.available.size(); i > newPoolSize - inUseSize; i--) {
+					T item = this.available.poll();
+					if (item != null) {
+						doRemoveItem(item);
+					}
+					else {
+						break;
+					}
 				}
-				else {
-					break;
+
+				int inUseDelta = poolSize - inUseSize;
+				if (inUseDelta < 0 && this.logger.isDebugEnabled()) {
+					this.logger.debug(String.format("Pool is overcommitted by %d; items will be removed when returned",
+							-inUseDelta));
 				}
 			}
-
-			int inUseDelta = poolSize - inUseSize;
-			if (inUseDelta < 0 && this.logger.isDebugEnabled()) {
-				this.logger.debug(String.format("Pool is overcommitted by %d; items will be removed when returned",
-						-inUseDelta));
-			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 
@@ -135,8 +146,14 @@ public class SimplePool<T> implements Pool<T> {
 	 * to be set.
 	 */
 	@Override
-	public synchronized int getPoolSize() {
-		return this.poolSize.get();
+	public int getPoolSize() {
+		this.lock.lock();
+		try {
+			return this.poolSize.get();
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
@@ -224,36 +241,48 @@ public class SimplePool<T> implements Pool<T> {
 	 * Return an item to the pool.
 	 */
 	@Override
-	public synchronized void releaseItem(T item) {
-		Assert.notNull(item, "Item cannot be null");
-		Assert.isTrue(this.allocated.contains(item),
-				"You can only release items that were obtained from the pool");
-		if (this.inUse.contains(item)) {
-			if (this.poolSize.get() > this.targetPoolSize.get() || this.closed) {
-				this.poolSize.decrementAndGet();
-				doRemoveItem(item);
+	public void releaseItem(T item) {
+		this.lock.lock();
+		try {
+			Assert.notNull(item, "Item cannot be null");
+			Assert.isTrue(this.allocated.contains(item),
+					"You can only release items that were obtained from the pool");
+			if (this.inUse.contains(item)) {
+				if (this.poolSize.get() > this.targetPoolSize.get() || this.closed) {
+					this.poolSize.decrementAndGet();
+					doRemoveItem(item);
+				}
+				else {
+					if (this.logger.isDebugEnabled()) {
+						this.logger.debug("Releasing " + item + " back to the pool");
+					}
+					this.available.add(item);
+					this.inUse.remove(item);
+					this.permits.release();
+				}
 			}
 			else {
 				if (this.logger.isDebugEnabled()) {
-					this.logger.debug("Releasing " + item + " back to the pool");
+					this.logger.debug("Ignoring release of " + item + " back to the pool - not in use");
 				}
-				this.available.add(item);
-				this.inUse.remove(item);
-				this.permits.release();
 			}
 		}
-		else {
-			if (this.logger.isDebugEnabled()) {
-				this.logger.debug("Ignoring release of " + item + " back to the pool - not in use");
-			}
+		finally {
+			this.lock.unlock();
 		}
 	}
 
 	@Override
-	public synchronized void removeAllIdleItems() {
-		T item;
-		while ((item = this.available.poll()) != null) {
-			doRemoveItem(item);
+	public void removeAllIdleItems() {
+		this.lock.lock();
+		try {
+			T item;
+			while ((item = this.available.poll()) != null) {
+				doRemoveItem(item);
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 
@@ -267,9 +296,15 @@ public class SimplePool<T> implements Pool<T> {
 	}
 
 	@Override
-	public synchronized void close() {
-		this.closed = true;
-		removeAllIdleItems();
+	public void close() {
+		this.lock.lock();
+		try {
+			this.closed = true;
+			removeAllIdleItems();
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@SuppressWarnings("serial")

spring-integration-feed/src/main/java/org/springframework/integration/feed/inbound/FeedEntryMessageSource.java

@@ -28,6 +28,8 @@ import java.util.Date;
 import java.util.List;
 import java.util.Queue;
 import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import com.rometools.rome.feed.synd.SyndEntry;
 import com.rometools.rome.feed.synd.SyndFeed;
@@ -56,6 +58,7 @@ import org.springframework.util.StringUtils;
  * @author Oleg Zhurakousky
  * @author Artem Bilan
  * @author Aaron Loes
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
@@ -69,13 +72,13 @@ public class FeedEntryMessageSource extends AbstractMessageSource<SyndEntry> {
 
 	private final Queue<SyndEntry> entries = new ConcurrentLinkedQueue<>();
 
-	private final Object monitor = new Object();
+	private final Lock monitor = new ReentrantLock();
 
 	private final Comparator<SyndEntry> syndEntryComparator =
 			Comparator.comparing(FeedEntryMessageSource::getLastModifiedDate,
 					Comparator.nullsFirst(Comparator.naturalOrder()));
 
-	private final Object feedMonitor = new Object();
+	private final Lock feedMonitor = new ReentrantLock();
 
 	private SyndFeedInput syndFeedInput = new SyndFeedInput();
 
@@ -176,7 +179,8 @@ public class FeedEntryMessageSource extends AbstractMessageSource<SyndEntry> {
 		Assert.isTrue(this.initialized,
 				"'FeedEntryReaderMessageSource' must be initialized before it can produce Messages.");
 		SyndEntry nextEntry;
-		synchronized (this.monitor) {
+		this.monitor.lock();
+		try {
 			nextEntry = getNextEntry();
 			if (nextEntry == null) {
 				// read feed and try again
@@ -184,6 +188,9 @@ public class FeedEntryMessageSource extends AbstractMessageSource<SyndEntry> {
 				nextEntry = getNextEntry();
 			}
 		}
+		finally {
+			this.monitor.unlock();
+		}
 		return nextEntry;
 	}
 
@@ -225,7 +232,8 @@ public class FeedEntryMessageSource extends AbstractMessageSource<SyndEntry> {
 
 	private SyndFeed getFeed() {
 		try {
-			synchronized (this.feedMonitor) {
+			this.feedMonitor.lock();
+			try {
 				SyndFeed feed = buildSyndFeed();
 				logger.debug(() -> "Retrieved feed for [" + this + "]");
 				if (feed == null) {
@@ -233,6 +241,9 @@ public class FeedEntryMessageSource extends AbstractMessageSource<SyndEntry> {
 				}
 				return feed;
 			}
+			finally {
+				this.feedMonitor.unlock();
+			}
 		}
 		catch (Exception e) {
 			throw new MessagingException("Failed to retrieve feed for '" + this + "'", e);

spring-integration-file/src/main/java/org/springframework/integration/file/FileWritingMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -40,6 +40,7 @@ import java.util.Map.Entry;
 import java.util.Set;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.BiConsumer;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -109,6 +110,7 @@ import org.springframework.util.StringUtils;
  * @author Tony Falabella
  * @author Alen Turkovic
  * @author Trung Pham
+ * @author Christian Tzolov
  */
 public class FileWritingMessageHandler extends AbstractReplyProducingMessageHandler
 		implements ManageableLifecycle, MessageTriggerAction {
@@ -130,6 +132,8 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 					PosixFilePermission.OWNER_READ
 			};
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Map<String, FileState> fileStates = new HashMap<>();
 
 	private final Expression destinationDirectoryExpression;
@@ -459,12 +463,16 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 
 	@Override
 	public void stop() {
-		synchronized (this) {
+		this.lock.lock();
+		try {
 			if (this.flushTask != null) {
 				this.flushTask.cancel(true);
 				this.flushTask = null;
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 		Flusher flusher = new Flusher();
 		flusher.run();
 		boolean needInterrupt = this.fileStates.size() > 0;
@@ -873,37 +881,42 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 		return destinationDirectory;
 	}
 
-	private synchronized FileState getFileState(File fileToWriteTo, boolean isString)
+	private FileState getFileState(File fileToWriteTo, boolean isString)
 			throws FileNotFoundException {
-
-		FileState state;
-		boolean appendNoFlush = FileExistsMode.APPEND_NO_FLUSH.equals(this.fileExistsMode);
-		if (appendNoFlush) {
-			String absolutePath = fileToWriteTo.getAbsolutePath();
-			state = this.fileStates.get(absolutePath);
-			if (state != null // NOSONAR
-					&& ((isString && state.stream != null) || (!isString && state.writer != null))) {
-				state.close();
+		this.lock.lock();
+		try {
+			FileState state;
+			boolean appendNoFlush = FileExistsMode.APPEND_NO_FLUSH.equals(this.fileExistsMode);
+			if (appendNoFlush) {
+				String absolutePath = fileToWriteTo.getAbsolutePath();
+				state = this.fileStates.get(absolutePath);
+				if (state != null // NOSONAR
+						&& ((isString && state.stream != null) || (!isString && state.writer != null))) {
+					state.close();
+					state = null;
+					this.fileStates.remove(absolutePath);
+				}
+				if (state == null) {
+					if (isString) {
+						state = new FileState(createWriter(fileToWriteTo, true),
+								this.lockRegistry.obtain(fileToWriteTo.getAbsolutePath()));
+					}
+					else {
+						state = new FileState(createOutputStream(fileToWriteTo, true),
+								this.lockRegistry.obtain(fileToWriteTo.getAbsolutePath()));
+					}
+					this.fileStates.put(absolutePath, state);
+				}
+				state.lastWrite = Long.MAX_VALUE; // prevent flush while we write
+			}
+			else {
 				state = null;
-				this.fileStates.remove(absolutePath);
 			}
-			if (state == null) {
-				if (isString) {
-					state = new FileState(createWriter(fileToWriteTo, true),
-							this.lockRegistry.obtain(fileToWriteTo.getAbsolutePath()));
-				}
-				else {
-					state = new FileState(createOutputStream(fileToWriteTo, true),
-							this.lockRegistry.obtain(fileToWriteTo.getAbsolutePath()));
-				}
-				this.fileStates.put(absolutePath, state);
-			}
-			state.lastWrite = Long.MAX_VALUE; // prevent flush while we write
+			return state;
 		}
-		else {
-			state = null;
+		finally {
+			this.lock.unlock();
 		}
-		return state;
 	}
 
 	/**
@@ -975,7 +988,8 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 
 	private Map<String, FileState> findFilesToFlush(MessageFlushPredicate flushPredicate, Message<?> filterMessage) {
 		Map<String, FileState> toRemove = new HashMap<>();
-		synchronized (this) {
+		this.lock.lock();
+		try {
 			Iterator<Entry<String, FileState>> iterator = this.fileStates.entrySet().iterator();
 			while (iterator.hasNext()) {
 				Entry<String, FileState> entry = iterator.next();
@@ -986,12 +1000,21 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 				}
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 		return toRemove;
 	}
 
-	private synchronized void clearState(final File fileToWriteTo, final FileState state) {
+	private void clearState(final File fileToWriteTo, final FileState state) {
 		if (state != null) {
-			this.fileStates.remove(fileToWriteTo.getAbsolutePath());
+			this.lock.lock();
+			try {
+				this.fileStates.remove(fileToWriteTo.getAbsolutePath());
+			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 	}
 
@@ -1014,11 +1037,15 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 				FileWritingMessageHandler.this.logger
 						.debug("Interrupted during flush; not flushed: " + toRestore.keySet());
 			}
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				for (Entry<String, FileState> entry : toRestore.entrySet()) {
 					this.fileStates.putIfAbsent(entry.getKey(), entry.getValue());
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 	}
 
@@ -1085,11 +1112,12 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 		@Override
 		public void run() {
 			Map<String, FileState> toRemove = new HashMap<>();
-			synchronized (FileWritingMessageHandler.this) {
+			FileWritingMessageHandler.this.lock.lock();
+			try {
 				long expired = FileWritingMessageHandler.this.flushTask == null ? Long.MAX_VALUE
 						: (System.currentTimeMillis() - FileWritingMessageHandler.this.flushInterval);
-				Iterator<Entry<String, FileState>> iterator =
-						FileWritingMessageHandler.this.fileStates.entrySet().iterator();
+				Iterator<Entry<String, FileState>> iterator = FileWritingMessageHandler.this.fileStates.entrySet()
+						.iterator();
 				while (iterator.hasNext()) {
 					Entry<String, FileState> entry = iterator.next();
 					FileState state = entry.getValue();
@@ -1100,6 +1128,9 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 					}
 				}
 			}
+			finally {
+				FileWritingMessageHandler.this.lock.unlock();
+			}
 			doFlush(toRemove);
 		}
 

spring-integration-file/src/main/java/org/springframework/integration/file/config/FileListFilterFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,8 @@ package org.springframework.integration.file.config;
 import java.io.File;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.integration.file.filters.AcceptAllFileListFilter;
@@ -34,6 +36,8 @@ import org.springframework.lang.NonNull;
  * @author Mark Fisher
  * @author Gunnar Hillert
  * @author Gary Russell
+ * @author Christian Tzolov
+ *
  * @since 1.0.3
  */
 public class FileListFilterFactoryBean implements FactoryBean<FileListFilter<File>> {
@@ -52,7 +56,7 @@ public class FileListFilterFactoryBean implements FactoryBean<FileListFilter<Fil
 
 	private volatile Boolean alwaysAcceptDirectories;
 
-	private final Object monitor = new Object();
+	private final Lock monitor = new ReentrantLock();
 
 	public void setFilter(FileListFilter<File> filter) {
 		this.filter = filter;
@@ -95,9 +99,13 @@ public class FileListFilterFactoryBean implements FactoryBean<FileListFilter<Fil
 	@NonNull
 	public FileListFilter<File> getObject() {
 		if (this.result == null) {
-			synchronized (this.monitor) {
+			this.monitor.lock();
+			try {
 				this.initializeFileListFilter();
 			}
+			finally {
+				this.monitor.unlock();
+			}
 		}
 		return this.result;
 	}

spring-integration-file/src/main/java/org/springframework/integration/file/filters/AcceptOnceFileListFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@ import java.util.List;
 import java.util.Queue;
 import java.util.Set;
 import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.lang.Nullable;
 
@@ -37,6 +39,7 @@ import org.springframework.lang.Nullable;
  * @author Josh Long
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class AcceptOnceFileListFilter<F> extends AbstractFileListFilter<F> implements ReversibleFileListFilter<F>,
 		ResettableFileListFilter<F> {
@@ -46,7 +49,7 @@ public class AcceptOnceFileListFilter<F> extends AbstractFileListFilter<F> imple
 
 	private final Set<F> seenSet = new HashSet<F>();
 
-	private final Object monitor = new Object();
+	private final Lock monitor = new ReentrantLock();
 
 
 	/**
@@ -69,7 +72,8 @@ public class AcceptOnceFileListFilter<F> extends AbstractFileListFilter<F> imple
 
 	@Override
 	public boolean accept(F file) {
-		synchronized (this.monitor) {
+		this.monitor.lock();
+		try {
 			if (this.seenSet.contains(file)) {
 				return false;
 			}
@@ -81,11 +85,15 @@ public class AcceptOnceFileListFilter<F> extends AbstractFileListFilter<F> imple
 			this.seenSet.add(file);
 			return true;
 		}
+		finally {
+			this.monitor.unlock();
+		}
 	}
 
 	@Override
 	public void rollback(F file, List<F> files) {
-		synchronized (this.monitor) {
+		this.monitor.lock();
+		try {
 			boolean rollingBack = false;
 			for (F fileToRollback : files) {
 				if (fileToRollback.equals(file)) {
@@ -96,6 +104,9 @@ public class AcceptOnceFileListFilter<F> extends AbstractFileListFilter<F> imple
 				}
 			}
 		}
+		finally {
+			this.monitor.unlock();
+		}
 	}
 
 	@Override

spring-integration-file/src/main/java/org/springframework/integration/file/filters/CompositeFileListFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,8 @@ import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Consumer;
 
 import org.springframework.beans.factory.InitializingBean;
@@ -46,6 +48,7 @@ import org.springframework.util.Assert;
  * @author Josh Long
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class CompositeFileListFilter<F>
 		implements ReversibleFileListFilter<F>, ResettableFileListFilter<F>, DiscardAwareFileListFilter<F>, Closeable {
@@ -58,6 +61,7 @@ public class CompositeFileListFilter<F>
 
 	private boolean oneIsForRecursion;
 
+	private final Lock lock = new ReentrantLock();
 
 	public CompositeFileListFilter() {
 		this.fileFilters = new LinkedHashSet<>();
@@ -104,24 +108,30 @@ public class CompositeFileListFilter<F>
 	 * @param filtersToAdd a list of filters to add
 	 * @return this CompositeFileListFilter instance with the added filters
 	 */
-	public synchronized CompositeFileListFilter<F> addFilters(Collection<? extends FileListFilter<F>> filtersToAdd) {
-		for (FileListFilter<F> elf : filtersToAdd) {
-			if (elf instanceof DiscardAwareFileListFilter) {
-				((DiscardAwareFileListFilter<F>) elf).addDiscardCallback(this.discardCallback);
-			}
-			if (elf instanceof InitializingBean) {
-				try {
-					((InitializingBean) elf).afterPropertiesSet();
+	public CompositeFileListFilter<F> addFilters(Collection<? extends FileListFilter<F>> filtersToAdd) {
+		this.lock.lock();
+		try {
+			for (FileListFilter<F> elf : filtersToAdd) {
+				if (elf instanceof DiscardAwareFileListFilter) {
+					((DiscardAwareFileListFilter<F>) elf).addDiscardCallback(this.discardCallback);
 				}
-				catch (Exception e) {
-					throw new IllegalStateException(e);
+				if (elf instanceof InitializingBean) {
+					try {
+						((InitializingBean) elf).afterPropertiesSet();
+					}
+					catch (Exception e) {
+						throw new IllegalStateException(e);
+					}
 				}
+				this.allSupportAccept = this.allSupportAccept && elf.supportsSingleFileFiltering();
+				this.oneIsForRecursion |= elf.isForRecursion();
 			}
-			this.allSupportAccept = this.allSupportAccept && elf.supportsSingleFileFiltering();
-			this.oneIsForRecursion |= elf.isForRecursion();
+			this.fileFilters.addAll(filtersToAdd);
+			return this;
+		}
+		finally {
+			this.lock.unlock();
 		}
-		this.fileFilters.addAll(filtersToAdd);
-		return this;
 	}
 
 	@Override

spring-integration-file/src/main/java/org/springframework/integration/file/remote/session/CachingSessionFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,8 @@ package org.springframework.integration.file.remote.session;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -40,6 +42,7 @@ import org.springframework.util.Assert;
  * @author Gary Russell
  * @author Alen Turkovic
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
@@ -47,6 +50,8 @@ public class CachingSessionFactory<F> implements SessionFactory<F>, DisposableBe
 
 	private static final Log LOGGER = LogFactory.getLog(CachingSessionFactory.class);
 
+	private final Lock lock = new ReentrantLock();
+
 	private final SessionFactory<F> sessionFactory;
 
 	private final SimplePool<Session<F>> pool;
@@ -146,24 +151,29 @@ public class CachingSessionFactory<F> implements SessionFactory<F>, DisposableBe
 	 * Clear the cache of sessions; also any in-use sessions will be closed when
 	 * returned to the cache.
 	 */
-	public synchronized void resetCache() {
-		LOGGER.debug("Cache reset; idle sessions will be removed, in-use sessions will be closed when returned");
-		if (this.isSharedSessionCapable && ((SharedSessionCapable) this.sessionFactory).isSharedSession()) {
-			((SharedSessionCapable) this.sessionFactory).resetSharedSession();
+	public void resetCache() {
+		this.lock.lock();
+		try {
+			LOGGER.debug("Cache reset; idle sessions will be removed, in-use sessions will be closed when returned");
+			if (this.isSharedSessionCapable && ((SharedSessionCapable) this.sessionFactory).isSharedSession()) {
+				((SharedSessionCapable) this.sessionFactory).resetSharedSession();
+			}
+			long epoch = System.nanoTime();
+			/*
+			 * Spin until we get a new value - nano precision but may be lower resolution. We reset the epoch AFTER
+			 * resetting the shared session so there is no possibility of an "old" session being created in the new
+			 * epoch. There is a slight possibility that a "new" session might appear in the old epoch and thus be
+			 * closed when returned to the cache.
+			 */
+			while (epoch == this.sharedSessionEpoch) {
+				epoch = System.nanoTime();
+			}
+			this.sharedSessionEpoch = epoch;
+			this.pool.removeAllIdleItems();
 		}
-		long epoch = System.nanoTime();
-		/*
-		 * Spin until we get a new value - nano precision but may be lower resolution.
-		 * We reset the epoch AFTER resetting the shared session so there is no possibility
-		 * of an "old" session being created in the new epoch. There is a slight possibility
-		 * that a "new" session might appear in the old epoch and thus be closed when returned to
-		 * the cache.
-		 */
-		while (epoch == this.sharedSessionEpoch) {
-			epoch = System.nanoTime();
+		finally {
+			this.lock.unlock();
 		}
-		this.sharedSessionEpoch = epoch;
-		this.pool.removeAllIdleItems();
 	}
 
 	public class CachedSession implements Session<F> { //NOSONAR must be final, but can't for mocking in tests
@@ -174,6 +184,8 @@ public class CachingSessionFactory<F> implements SessionFactory<F>, DisposableBe
 
 		private boolean dirty;
 
+		private final Lock lock = new ReentrantLock();
+
 		/**
 		 * The epoch in which this session was created.
 		 */
@@ -185,35 +197,42 @@ public class CachingSessionFactory<F> implements SessionFactory<F>, DisposableBe
 		}
 
 		@Override
-		public synchronized void close() {
-			if (this.released) {
-				if (LOGGER.isDebugEnabled()) {
-					LOGGER.debug("Session " + this.targetSession + " already released.");
+		public void close() {
+			this.lock.lock();
+			try {
+
+				if (this.released) {
+					if (LOGGER.isDebugEnabled()) {
+						LOGGER.debug("Session " + this.targetSession + " already released.");
+					}
+				}
+				else {
+					if (LOGGER.isDebugEnabled()) {
+						LOGGER.debug("Releasing Session " + this.targetSession + " back to the pool.");
+					}
+					if (this.sharedSessionEpoch != CachingSessionFactory.this.sharedSessionEpoch) {
+						if (LOGGER.isDebugEnabled()) {
+							LOGGER.debug("Closing session " + this.targetSession + " after reset.");
+						}
+						this.targetSession.close();
+					}
+					else if (this.dirty) {
+						this.targetSession.close();
+					}
+					if (this.targetSession.isOpen()) {
+						try {
+							this.targetSession.finalizeRaw();
+						}
+						catch (IOException e) {
+							// No-op in this context
+						}
+					}
+					CachingSessionFactory.this.pool.releaseItem(this.targetSession);
+					this.released = true;
 				}
 			}
-			else {
-				if (LOGGER.isDebugEnabled()) {
-					LOGGER.debug("Releasing Session " + this.targetSession + " back to the pool.");
-				}
-				if (this.sharedSessionEpoch != CachingSessionFactory.this.sharedSessionEpoch) {
-					if (LOGGER.isDebugEnabled()) {
-						LOGGER.debug("Closing session " + this.targetSession + " after reset.");
-					}
-					this.targetSession.close();
-				}
-				else if (this.dirty) {
-					this.targetSession.close();
-				}
-				if (this.targetSession.isOpen()) {
-					try {
-						this.targetSession.finalizeRaw();
-					}
-					catch (IOException e) {
-						//No-op in this context
-					}
-				}
-				CachingSessionFactory.this.pool.releaseItem(this.targetSession);
-				this.released = true;
+			finally {
+				this.lock.unlock();
 			}
 		}
 

spring-integration-hazelcast/src/main/java/org/springframework/integration/hazelcast/leader/LeaderInitiator.java

@@ -21,6 +21,8 @@ import java.util.concurrent.Callable;
 import java.util.concurrent.Future;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import com.hazelcast.core.HazelcastInstance;
 import com.hazelcast.cp.CPSubsystem;
@@ -54,6 +56,7 @@ import org.springframework.util.Assert;
  * @author Mael Le Guével
  * @author Alexey Tsoy
  * @author Robert Höglund
+ * @author Christian Tzolov
  */
 public class LeaderInitiator implements SmartLifecycle, DisposableBean, ApplicationEventPublisherAware {
 
@@ -61,6 +64,8 @@ public class LeaderInitiator implements SmartLifecycle, DisposableBean, Applicat
 
 	private static final Context NULL_CONTEXT = new NullContext();
 
+	private final Lock lock = new ReentrantLock();
+
 	/*** Hazelcast client.
 	 */
 	private final HazelcastInstance client;
@@ -208,11 +213,17 @@ public class LeaderInitiator implements SmartLifecycle, DisposableBean, Applicat
 	 * Start the registration of the {@link #candidate} for leader election.
 	 */
 	@Override
-	public synchronized void start() {
-		if (!this.running) {
-			this.leaderSelector = new LeaderSelector();
-			this.running = true;
-			this.future = this.taskExecutor.submit(this.leaderSelector);
+	public void start() {
+		this.lock.lock();
+		try {
+			if (!this.running) {
+				this.leaderSelector = new LeaderSelector();
+				this.running = true;
+				this.future = this.taskExecutor.submit(this.leaderSelector);
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 
@@ -227,13 +238,19 @@ public class LeaderInitiator implements SmartLifecycle, DisposableBean, Applicat
 	 * If the candidate is currently leader, its leadership will be revoked.
 	 */
 	@Override
-	public synchronized void stop() {
-		if (this.running) {
-			this.running = false;
-			if (this.future != null) {
-				this.future.cancel(true);
+	public void stop() {
+		this.lock.lock();
+		try {
+			if (this.running) {
+				this.running = false;
+				if (this.future != null) {
+					this.future.cancel(true);
+				}
+				this.future = null;
 			}
-			this.future = null;
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-http/src/main/java/org/springframework/integration/http/outbound/AbstractHttpRequestExecutingMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2022 the original author or authors.
+ * Copyright 2017-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,8 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.xml.transform.Source;
 
@@ -71,6 +73,7 @@ import org.springframework.web.util.DefaultUriBuilderFactory;
  * @author Wallace Wadge
  * @author Shiliang Li
  * @author Florian Schöffl
+ * @author Christian Tzolov
  *
  * @since 5.0
  */
@@ -81,6 +84,8 @@ public abstract class AbstractHttpRequestExecutingMessageHandler extends Abstrac
 
 	protected final DefaultUriBuilderFactory uriFactory = new DefaultUriBuilderFactory(); // NOSONAR - final
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Map<String, Expression> uriVariableExpressions = new HashMap<>();
 
 	private final Expression uriExpression;
@@ -226,10 +231,14 @@ public abstract class AbstractHttpRequestExecutingMessageHandler extends Abstrac
 	 * @param uriVariableExpressions The URI variable expressions.
 	 */
 	public void setUriVariableExpressions(Map<String, Expression> uriVariableExpressions) {
-		synchronized (this.uriVariableExpressions) {
+		this.lock.lock();
+		try {
 			this.uriVariableExpressions.clear();
 			this.uriVariableExpressions.putAll(uriVariableExpressions);
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	/**

spring-integration-ip/src/main/java/org/springframework/integration/ip/AbstractInternetProtocolSendingMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@ package org.springframework.integration.ip;
 
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.integration.handler.AbstractMessageHandler;
 import org.springframework.integration.support.management.ManageableLifecycle;
@@ -27,11 +29,15 @@ import org.springframework.util.Assert;
  * Base class for UDP MessageHandlers.
  *
  * @author Gary Russell
+ * @author Christian Tzolov
+ *
  * @since 2.0
  */
 public abstract class AbstractInternetProtocolSendingMessageHandler extends AbstractMessageHandler
 		implements CommonSocketOptions, ManageableLifecycle {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final SocketAddress destinationAddress;
 
 	private final String host;
@@ -119,20 +125,32 @@ public abstract class AbstractInternetProtocolSendingMessageHandler extends Abst
 
 
 	@Override
-	public synchronized void start() {
-		if (!this.running) {
-			this.doStart();
-			this.running = true;
+	public void start() {
+		this.lock.lock();
+		try {
+			if (!this.running) {
+				this.doStart();
+				this.running = true;
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 
 	protected abstract void doStart();
 
 	@Override
-	public synchronized void stop() {
-		if (this.running) {
-			this.doStop();
-			this.running = false;
+	public void stop() {
+		this.lock.lock();
+		try {
+			if (this.running) {
+				this.doStop();
+				this.running = false;
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/TcpSendingMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@ import java.time.Duration;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.integration.handler.AbstractMessageHandler;
@@ -48,6 +50,7 @@ import org.springframework.util.Assert;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  *
@@ -60,7 +63,7 @@ public class TcpSendingMessageHandler extends AbstractMessageHandler implements
 	 */
 	public static final long DEFAULT_RETRY_INTERVAL = 60000;
 
-	protected final Object lifecycleMonitor = new Object(); // NOSONAR
+	protected final Lock lifecycleMonitor = new ReentrantLock(); // NOSONAR
 
 	private final Map<String, TcpConnection> connections = new ConcurrentHashMap<>();
 
@@ -251,7 +254,8 @@ public class TcpSendingMessageHandler extends AbstractMessageHandler implements
 
 	@Override
 	public void start() {
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (!this.active) {
 				this.active = true;
 				if (this.clientConnectionFactory != null) {
@@ -273,11 +277,15 @@ public class TcpSendingMessageHandler extends AbstractMessageHandler implements
 				}
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 	}
 
 	@Override
 	public void stop() {
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (this.active) {
 				this.active = false;
 				if (this.scheduledFuture != null) {
@@ -292,6 +300,9 @@ public class TcpSendingMessageHandler extends AbstractMessageHandler implements
 				}
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 	}
 
 	@Override

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/AbstractConnectionFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,6 +42,8 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.ApplicationEventPublisherAware;
@@ -58,6 +60,7 @@ import org.springframework.util.Assert;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  *
@@ -73,10 +76,12 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 
 	private static final int DEFAULT_READ_DELAY = 100;
 
-	protected final Object lifecycleMonitor = new Object(); // NOSONAR final
+	protected final Lock lifecycleMonitor = new ReentrantLock(); // NOSONAR final
 
 	private final Map<String, TcpConnectionSupport> connections = new ConcurrentHashMap<>();
 
+	private final Lock connectionsMonitor = new ReentrantLock();
+
 	private final BlockingQueue<PendingIO> delayedReads = new LinkedBlockingQueue<>();
 
 	private final List<TcpSender> senders = Collections.synchronizedList(new ArrayList<>());
@@ -546,13 +551,17 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 		if (!this.active) {
 			throw new MessagingException("Connection Factory not started");
 		}
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (this.taskExecutor == null) {
 				this.privateExecutor = true;
 				this.taskExecutor = Executors.newCachedThreadPool();
 			}
 			return this.taskExecutor;
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 	}
 
 	/**
@@ -561,7 +570,8 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 	@Override
 	public void stop() {
 		this.active = false;
-		synchronized (this.connections) {
+		this.connectionsMonitor.lock();
+		try {
 			Iterator<Entry<String, TcpConnectionSupport>> iterator = this.connections.entrySet().iterator();
 			while (iterator.hasNext()) {
 				TcpConnectionSupport connection = iterator.next().getValue();
@@ -575,7 +585,12 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 				}
 			}
 		}
-		synchronized (this.lifecycleMonitor) {
+		finally {
+			this.connectionsMonitor.unlock();
+		}
+
+		this.lifecycleMonitor.lock();
+		try {
 			if (this.privateExecutor) {
 				ExecutorService executorService = (ExecutorService) this.taskExecutor;
 				executorService.shutdown();
@@ -598,6 +613,9 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 				}
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 		logger.info(() -> "stopped " + this);
 	}
 
@@ -849,7 +867,8 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 	}
 
 	protected void addConnection(TcpConnectionSupport connection) {
-		synchronized (this.connections) {
+		this.connectionsMonitor.lock();
+		try {
 			if (!this.active) {
 				connection.close();
 				return;
@@ -857,6 +876,9 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 			this.connections.put(connection.getConnectionId(), connection);
 			logger.debug(() -> getComponentName() + ": Added new connection: " + connection.getConnectionId());
 		}
+		finally {
+			this.connectionsMonitor.unlock();
+		}
 	}
 
 	/**
@@ -864,7 +886,8 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 	 * @return a list of open connection ids.
 	 */
 	private List<String> removeClosedConnectionsAndReturnOpenConnectionIds() {
-		synchronized (this.connections) {
+		this.connectionsMonitor.lock();
+		try {
 			List<String> openConnectionIds = new ArrayList<>();
 			Iterator<Entry<String, TcpConnectionSupport>> iterator = this.connections.entrySet().iterator();
 			while (iterator.hasNext()) {
@@ -888,6 +911,9 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 			}
 			return openConnectionIds;
 		}
+		finally {
+			this.connectionsMonitor.unlock();
+		}
 	}
 
 	/**
@@ -948,7 +974,8 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 	public boolean closeConnection(String connectionId) {
 		Assert.notNull(connectionId, "'connectionId' to close must not be null");
 		// closed connections are removed from #connections in #harvestClosedConnections()
-		synchronized (this.connections) {
+		this.connectionsMonitor.lock();
+		try {
 			boolean closed = false;
 			TcpConnectionSupport connection = this.connections.remove(connectionId);
 			if (connection != null) {
@@ -964,6 +991,9 @@ public abstract class AbstractConnectionFactory extends IntegrationObjectSupport
 			}
 			return closed;
 		}
+		finally {
+			this.connectionsMonitor.unlock();
+		}
 	}
 
 	@Override

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/AbstractServerConnectionFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2022 the original author or authors.
+ * Copyright 2001-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,6 +37,7 @@ import org.springframework.util.Assert;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
@@ -75,13 +76,17 @@ public abstract class AbstractServerConnectionFactory extends AbstractConnection
 
 	@Override
 	public void start() {
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (!isActive()) {
 				this.setActive(true);
 				this.shuttingDown = false;
 				getTaskExecutor().execute(this);
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 		super.start();
 	}
 

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/CachingClientConnectionFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,8 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.core.serializer.Deserializer;
@@ -39,11 +41,15 @@ import org.springframework.messaging.support.ErrorMessage;
  * false, or cache starvation will result.
  *
  * @author Gary Russell
+ * @author Christian Tzolov
+ *
  * @since 2.2
  *
  */
 public class CachingClientConnectionFactory extends AbstractClientConnectionFactory implements DisposableBean {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final AbstractClientConnectionFactory targetConnectionFactory;
 
 	private final SimplePool<TcpConnectionSupport> pool;
@@ -385,9 +391,15 @@ public class CachingClientConnectionFactory extends AbstractClientConnectionFact
 	}
 
 	@Override
-	public synchronized void stop() {
-		this.targetConnectionFactory.stop();
-		this.pool.removeAllIdleItems();
+	public void stop() {
+		this.lock.lock();
+		try {
+			this.targetConnectionFactory.stop();
+			this.pool.removeAllIdleItems();
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/ClientModeConnectionManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,8 @@
 package org.springframework.integration.ip.tcp.connection;
 
 import java.util.Objects;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -31,6 +33,7 @@ import org.springframework.util.Assert;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.1
  *
@@ -39,6 +42,8 @@ public class ClientModeConnectionManager implements Runnable {
 
 	private final Log logger = LogFactory.getLog(this.getClass());
 
+	private final Lock lock = new ReentrantLock();
+
 	private final AbstractConnectionFactory clientConnectionFactory;
 
 	private volatile TcpConnection lastConnection;
@@ -54,7 +59,8 @@ public class ClientModeConnectionManager implements Runnable {
 
 	@Override
 	public void run() {
-		synchronized (this.clientConnectionFactory) {
+		this.lock.lock();
+		try {
 			try {
 				TcpConnection connection = this.clientConnectionFactory.getConnection();
 				if (!Objects.equals(connection, this.lastConnection)) {
@@ -73,6 +79,9 @@ public class ClientModeConnectionManager implements Runnable {
 				this.logger.error("Could not establish connection using " + this.clientConnectionFactory, ex);
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	public boolean isConnected() {

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/FailoverClientConnectionFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.UUID;
 import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.net.ssl.SSLSession;
 
@@ -37,6 +39,8 @@ import org.springframework.util.Assert;
  * succeeds or the list is exhausted.
  *
  * @author Gary Russell
+ * @author Christian Tzolov
+ *
  * @since 2.2
  *
  */
@@ -224,6 +228,8 @@ public class FailoverClientConnectionFactory extends AbstractClientConnectionFac
 	 */
 	private final class FailoverTcpConnection extends TcpConnectionSupport implements TcpListener {
 
+		private final Lock lock = new ReentrantLock();
+
 		private final List<AbstractClientConnectionFactory> connectionFactories;
 
 		private final String connectionId;
@@ -257,45 +263,50 @@ public class FailoverClientConnectionFactory extends AbstractClientConnectionFac
 		 * factories are down.
 		 * @throws InterruptedException if interrupted.
 		 */
-		private synchronized void findAConnection() throws InterruptedException {
-			boolean success = false;
-			AbstractClientConnectionFactory lastFactoryToTry = this.currentFactory;
-			AbstractClientConnectionFactory nextFactory = null;
-			if (!this.factoryIterator.hasNext()) {
-				this.factoryIterator = this.connectionFactories.iterator();
+		private void findAConnection() throws InterruptedException {
+			this.lock.lock();
+			try {
+				boolean success = false;
+				AbstractClientConnectionFactory lastFactoryToTry = this.currentFactory;
+				AbstractClientConnectionFactory nextFactory = null;
+				if (!this.factoryIterator.hasNext()) {
+					this.factoryIterator = this.connectionFactories.iterator();
+				}
+				boolean restartedList = false;
+				while (!success) {
+					try {
+						nextFactory = this.factoryIterator.next();
+						this.delegate = nextFactory.getConnection();
+						if (logger.isDebugEnabled()) {
+							logger.debug("Got " + this.delegate.getConnectionId() + " from " + nextFactory);
+						}
+						this.delegate.registerListener(this);
+						this.currentFactory = nextFactory;
+						success = this.delegate.isOpen();
+					}
+					catch (RuntimeException e) {
+						if (logger.isDebugEnabled()) {
+							logger.debug(nextFactory + " failed with "
+									+ e.toString()
+									+ ", trying another");
+						}
+						if (restartedList && (lastFactoryToTry == null || lastFactoryToTry.equals(nextFactory))) {
+							logger.debug("Failover failed to find a connection");
+							/*
+							 * We've tried every factory including the one the current connection was on.
+							 */
+							this.open = false;
+							throw e;
+						}
+						if (!this.factoryIterator.hasNext()) {
+							this.factoryIterator = this.connectionFactories.iterator();
+							restartedList = true;
+						}
+					}
+				}
 			}
-			boolean restartedList = false;
-			while (!success) {
-				try {
-					nextFactory = this.factoryIterator.next();
-					this.delegate = nextFactory.getConnection();
-					if (logger.isDebugEnabled()) {
-						logger.debug("Got " + this.delegate.getConnectionId() + " from " + nextFactory);
-					}
-					this.delegate.registerListener(this);
-					this.currentFactory = nextFactory;
-					success = this.delegate.isOpen();
-				}
-				catch (RuntimeException e) {
-					if (logger.isDebugEnabled()) {
-						logger.debug(nextFactory + " failed with "
-								+ e.toString()
-								+ ", trying another");
-					}
-					if (restartedList && (lastFactoryToTry == null || lastFactoryToTry.equals(nextFactory))) {
-						logger.debug("Failover failed to find a connection");
-						/*
-						 *  We've tried every factory including the
-						 *  one the current connection was on.
-						 */
-						this.open = false;
-						throw e;
-					}
-					if (!this.factoryIterator.hasNext()) {
-						this.factoryIterator = this.connectionFactories.iterator();
-						restartedList = true;
-					}
-				}
+			finally {
+				this.lock.unlock();
 			}
 		}
 
@@ -316,39 +327,46 @@ public class FailoverClientConnectionFactory extends AbstractClientConnectionFac
 		 * If send fails on a connection from every factory, we give up.
 		 */
 		@Override
-		public synchronized void send(Message<?> message) {
-			boolean success = false;
-			AbstractClientConnectionFactory lastFactoryToTry = this.currentFactory;
-			AbstractClientConnectionFactory lastFactoryTried = null;
-			boolean retried = false;
-			while (!success) {
-				try {
-					lastFactoryTried = this.currentFactory;
-					this.delegate.send(message);
-					success = true;
-				}
-				catch (RuntimeException e) {
-					if (retried && lastFactoryTried.equals(lastFactoryToTry)) {
-						logger.error("All connection factories exhausted", e);
-						this.open = false;
-						throw e;
-					}
-					retried = true;
-					if (logger.isDebugEnabled()) {
-						logger.debug("Send to " + this.delegate.getConnectionId() + " failed; attempting failover", e);
-					}
-					this.delegate.close();
+		public void send(Message<?> message) {
+			this.lock.lock();
+			try {
+				boolean success = false;
+				AbstractClientConnectionFactory lastFactoryToTry = this.currentFactory;
+				AbstractClientConnectionFactory lastFactoryTried = null;
+				boolean retried = false;
+				while (!success) {
 					try {
-						findAConnection();
+						lastFactoryTried = this.currentFactory;
+						this.delegate.send(message);
+						success = true;
 					}
-					catch (@SuppressWarnings("unused") InterruptedException e1) {
-						Thread.currentThread().interrupt();
-					}
-					if (logger.isDebugEnabled()) {
-						logger.debug("Failing over to " + this.delegate.getConnectionId());
+					catch (RuntimeException e) {
+						if (retried && lastFactoryTried.equals(lastFactoryToTry)) {
+							logger.error("All connection factories exhausted", e);
+							this.open = false;
+							throw e;
+						}
+						retried = true;
+						if (logger.isDebugEnabled()) {
+							logger.debug("Send to " + this.delegate.getConnectionId() + " failed; attempting failover",
+									e);
+						}
+						this.delegate.close();
+						try {
+							findAConnection();
+						}
+						catch (@SuppressWarnings("unused") InterruptedException e1) {
+							Thread.currentThread().interrupt();
+						}
+						if (logger.isDebugEnabled()) {
+							logger.debug("Failing over to " + this.delegate.getConnectionId());
+						}
 					}
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 
 		@Override

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpConnectionInterceptorSupport.java

@@ -18,6 +18,8 @@ package org.springframework.integration.ip.tcp.connection;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.net.ssl.SSLSession;
 
@@ -34,11 +36,14 @@ import org.springframework.messaging.support.ErrorMessage;
  *
  * @author Gary Russell
  * @author Kazuki Shimizu
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
 public abstract class TcpConnectionInterceptorSupport extends TcpConnectionSupport implements TcpConnectionInterceptor {
 
+	private final Lock lock = new ReentrantLock();
+
 	private TcpConnectionSupport theConnection;
 
 	private TcpListener tcpListener;
@@ -238,17 +243,23 @@ public abstract class TcpConnectionInterceptorSupport extends TcpConnectionSuppo
 	}
 
 	@Override
-	public synchronized void removeDeadConnection(TcpConnection connection) {
-		if (this.removed) {
-			return;
+	public void removeDeadConnection(TcpConnection connection) {
+		this.lock.lock();
+		try {
+			if (this.removed) {
+				return;
+			}
+			this.removed = true;
+			if (this.theConnection instanceof TcpConnectionInterceptorSupport && !this.theConnection.equals(this)) {
+				((TcpConnectionInterceptorSupport) this.theConnection).removeDeadConnection(this);
+			}
+			TcpSender sender = getSender();
+			if (sender != null && !(sender instanceof TcpConnectionInterceptorSupport)) {
+				this.interceptedSenders.forEach(snder -> snder.removeDeadConnection(connection));
+			}
 		}
-		this.removed = true;
-		if (this.theConnection instanceof TcpConnectionInterceptorSupport && !this.theConnection.equals(this)) {
-			((TcpConnectionInterceptorSupport) this.theConnection).removeDeadConnection(this);
-		}
-		TcpSender sender = getSender();
-		if (sender != null && !(sender instanceof TcpConnectionInterceptorSupport)) {
-			this.interceptedSenders.forEach(snder -> snder.removeDeadConnection(connection));
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpNetConnection.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2021 the original author or authors.
+ * Copyright 2001-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,8 @@ import java.io.UncheckedIOException;
 import java.net.Socket;
 import java.net.SocketException;
 import java.net.SocketTimeoutException;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Supplier;
 
 import javax.net.ssl.SSLSession;
@@ -43,12 +45,15 @@ import org.springframework.util.Assert;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  *
  */
 public class TcpNetConnection extends TcpConnectionSupport implements SchedulingAwareRunnable {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Socket socket;
 
 	private volatile OutputStream socketOutputStream;
@@ -102,7 +107,8 @@ public class TcpNetConnection extends TcpConnectionSupport implements Scheduling
 
 	@Override
 	@SuppressWarnings("unchecked")
-	public synchronized void send(Message<?> message) {
+	public void send(Message<?> message) {
+		this.lock.lock();
 		try {
 			if (this.socketOutputStream == null) {
 				int writeBufferSize = this.socket.getSendBufferSize();
@@ -121,6 +127,9 @@ public class TcpNetConnection extends TcpConnectionSupport implements Scheduling
 			closeConnection(true);
 			throw mex;
 		}
+		finally {
+			this.lock.unlock();
+		}
 		if (logger.isDebugEnabled()) {
 			logger.debug(getConnectionId() + " Message sent " + message);
 		}

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpNioClientConnectionFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,6 +39,7 @@ import org.springframework.util.Assert;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  *
@@ -170,12 +171,16 @@ public class TcpNioClientConnectionFactory extends
 
 	@Override
 	public void start() {
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (!isActive()) {
 				setActive(true);
 				getTaskExecutor().execute(this);
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 		super.start();
 	}
 

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpNioConnection.java

@@ -37,6 +37,8 @@ import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.net.ssl.SSLSession;
 
@@ -56,6 +58,7 @@ import org.springframework.util.Assert;
  * @author John Anderson
  * @author Artem Bilan
  * @author David Herschler Shvo
+ * @author Christian Tzolov
  *
  * @since 2.0
  *
@@ -72,14 +75,20 @@ public class TcpNioConnection extends TcpConnectionSupport {
 
 	private static final byte[] EOF = new byte[0]; // EOF marker buffer
 
+	private final Lock lock = new ReentrantLock();
+
 	private final SocketChannel socketChannel;
 
+	private final Lock socketChannelMonitor = new ReentrantLock();
+
 	private final ChannelOutputStream channelOutputStream = new ChannelOutputStream();
 
 	private final ChannelInputStream channelInputStream = new ChannelInputStream();
 
 	private final AtomicInteger executionControl = new AtomicInteger();
 
+	private final Lock executionControlMonitor = new ReentrantLock();
+
 	private boolean usingDirectBuffers;
 
 	private long pipeTimeout = DEFAULT_PIPE_TIMEOUT;
@@ -154,7 +163,8 @@ public class TcpNioConnection extends TcpConnectionSupport {
 	@Override
 	@SuppressWarnings("unchecked")
 	public void send(Message<?> message) {
-		synchronized (this.socketChannel) {
+		this.socketChannelMonitor.lock();
+		try {
 			try {
 				if (this.bufferedOutputStream == null) {
 					int writeBufferSize = this.socketChannel.socket().getSendBufferSize();
@@ -177,6 +187,9 @@ public class TcpNioConnection extends TcpConnectionSupport {
 				logger.debug(getConnectionId() + " Message sent " + message);
 			}
 		}
+		finally {
+			this.socketChannelMonitor.unlock();
+		}
 	}
 
 	@Override
@@ -311,7 +324,8 @@ public class TcpNioConnection extends TcpConnectionSupport {
 		// timing was such that we were the last assembler and
 		// a new one wasn't run
 		if (dataAvailable()) {
-			synchronized (this.executionControl) {
+			this.executionControlMonitor.lock();
+			try {
 				if (this.executionControl.incrementAndGet() <= 1) {
 					// only continue if we don't already have another assembler running
 					this.executionControl.set(1);
@@ -322,6 +336,9 @@ public class TcpNioConnection extends TcpConnectionSupport {
 					this.executionControl.decrementAndGet();
 				}
 			}
+			finally {
+				this.executionControlMonitor.unlock();
+			}
 		}
 		if (moreDataAvailable) {
 			if (logger.isTraceEnabled()) {
@@ -352,43 +369,50 @@ public class TcpNioConnection extends TcpConnectionSupport {
 	 * @throws IOException an IO exception
 	 */
 	@Nullable
-	private synchronized Message<?> convert() throws IOException {
-		if (logger.isTraceEnabled()) {
-			logger.trace(getConnectionId() + " checking data avail (convert): " + this.channelInputStream.available() +
-					" pending: " + (this.writingToPipe));
-		}
-		if (this.channelInputStream.available() <= 0) {
-			try {
-				if (this.writingLatch.await(SIXTY, TimeUnit.SECONDS)) {
-					if (this.channelInputStream.available() <= 0) {
-						return null;
+	private Message<?> convert() throws IOException {
+		this.lock.lock();
+		try {
+			if (logger.isTraceEnabled()) {
+				logger.trace(
+						getConnectionId() + " checking data avail (convert): " + this.channelInputStream.available() +
+								" pending: " + (this.writingToPipe));
+			}
+			if (this.channelInputStream.available() <= 0) {
+				try {
+					if (this.writingLatch.await(SIXTY, TimeUnit.SECONDS)) {
+						if (this.channelInputStream.available() <= 0) {
+							return null;
+						}
+					}
+					else { // should never happen
+						throw new IOException("Timed out waiting for IO");
 					}
 				}
-				else { // should never happen
-					throw new IOException("Timed out waiting for IO");
+				catch (InterruptedException e) {
+					Thread.currentThread().interrupt();
+					throw new IOException("Interrupted waiting for IO", e);
 				}
 			}
-			catch (InterruptedException e) {
-				Thread.currentThread().interrupt();
-				throw new IOException("Interrupted waiting for IO", e);
+			try {
+				return getMapper().toMessage(this);
+			}
+			catch (Exception e) {
+				closeConnection(true);
+				if (e instanceof SocketTimeoutException) { // NOSONAR instanceof
+					if (logger.isDebugEnabled()) {
+						logger.debug("Closing socket after timeout " + getConnectionId());
+					}
+				}
+				else {
+					if (!(e instanceof SoftEndOfStreamException)) { // NOSONAR instanceof
+						throw e;
+					}
+				}
+				return null;
 			}
 		}
-		try {
-			return getMapper().toMessage(this);
-		}
-		catch (Exception e) {
-			closeConnection(true);
-			if (e instanceof SocketTimeoutException) { // NOSONAR instanceof
-				if (logger.isDebugEnabled()) {
-					logger.debug("Closing socket after timeout " + getConnectionId());
-				}
-			}
-			else {
-				if (!(e instanceof SoftEndOfStreamException)) { // NOSONAR instanceof
-					throw e;
-				}
-			}
-			return null;
+		finally {
+			this.lock.unlock();
 		}
 	}
 
@@ -468,7 +492,8 @@ public class TcpNioConnection extends TcpConnectionSupport {
 	}
 
 	private void checkForAssembler() {
-		synchronized (this.executionControl) {
+		this.executionControlMonitor.lock();
+		try {
 			if (this.executionControl.incrementAndGet() <= 1) {
 				// only execute run() if we don't already have one running
 				this.executionControl.set(1);
@@ -489,6 +514,9 @@ public class TcpNioConnection extends TcpConnectionSupport {
 				this.executionControl.decrementAndGet();
 			}
 		}
+		finally {
+			this.executionControlMonitor.unlock();
+		}
 	}
 
 	/**
@@ -605,6 +633,8 @@ public class TcpNioConnection extends TcpConnectionSupport {
 
 		private int soTimeout;
 
+		private final Lock innerLock = new ReentrantLock();
+
 		@Override
 		public void write(int b) throws IOException {
 			byte[] bytes = new byte[1];
@@ -632,28 +662,35 @@ public class TcpNioConnection extends TcpConnectionSupport {
 			doWrite(buffer);
 		}
 
-		protected synchronized void doWrite(ByteBuffer buffer) throws IOException {
-			if (logger.isDebugEnabled()) {
-				logger.debug(getConnectionId() + " writing " + buffer.remaining());
-			}
-			TcpNioConnection.this.socketChannel.write(buffer);
-			int remaining = buffer.remaining();
-			if (remaining == 0) {
-				return;
-			}
-			if (this.selector == null) {
-				this.selector = Selector.open();
-				this.soTimeout = TcpNioConnection.this.socketChannel.socket().getSoTimeout();
-			}
-			TcpNioConnection.this.socketChannel.register(this.selector, SelectionKey.OP_WRITE);
-			while (remaining > 0) {
-				int selectionCount = this.selector.select(this.soTimeout);
-				if (selectionCount == 0) {
-					throw new SocketTimeoutException("Timeout on write");
+		protected void doWrite(ByteBuffer buffer) throws IOException {
+			this.innerLock.lock();
+			try {
+
+				if (logger.isDebugEnabled()) {
+					logger.debug(getConnectionId() + " writing " + buffer.remaining());
 				}
-				this.selector.selectedKeys().clear();
 				TcpNioConnection.this.socketChannel.write(buffer);
-				remaining = buffer.remaining();
+				int remaining = buffer.remaining();
+				if (remaining == 0) {
+					return;
+				}
+				if (this.selector == null) {
+					this.selector = Selector.open();
+					this.soTimeout = TcpNioConnection.this.socketChannel.socket().getSoTimeout();
+				}
+				TcpNioConnection.this.socketChannel.register(this.selector, SelectionKey.OP_WRITE);
+				while (remaining > 0) {
+					int selectionCount = this.selector.select(this.soTimeout);
+					if (selectionCount == 0) {
+						throw new SocketTimeoutException("Timeout on write");
+					}
+					this.selector.selectedKeys().clear();
+					TcpNioConnection.this.socketChannel.write(buffer);
+					remaining = buffer.remaining();
+				}
+			}
+			finally {
+				this.innerLock.unlock();
 			}
 		}
 
@@ -680,6 +717,8 @@ public class TcpNioConnection extends TcpConnectionSupport {
 
 		private volatile boolean isClosed;
 
+		private final Lock innerLock = new ReentrantLock();
+
 		@Override
 		public int read(byte[] b, int off, int len) throws IOException {
 			Assert.notNull(b, "byte[] cannot be null");
@@ -708,30 +747,36 @@ public class TcpNioConnection extends TcpConnectionSupport {
 		}
 
 		@Override
-		public synchronized int read() throws IOException {
-			if (this.isClosed && this.available.get() == 0) {
-				if (TcpNioConnection.this.timedOut) {
-					throw new SocketTimeoutException("Connection has timed out");
-				}
-				return -1;
-			}
-			if (this.currentBuffer == null) {
-				this.currentBuffer = getNextBuffer();
-				this.currentOffset = 0;
-				if (this.currentBuffer == null) {
+		public int read() throws IOException {
+			this.innerLock.lock();
+			try {
+				if (this.isClosed && this.available.get() == 0) {
 					if (TcpNioConnection.this.timedOut) {
 						throw new SocketTimeoutException("Connection has timed out");
 					}
 					return -1;
 				}
+				if (this.currentBuffer == null) {
+					this.currentBuffer = getNextBuffer();
+					this.currentOffset = 0;
+					if (this.currentBuffer == null) {
+						if (TcpNioConnection.this.timedOut) {
+							throw new SocketTimeoutException("Connection has timed out");
+						}
+						return -1;
+					}
+				}
+				int bite;
+				bite = this.currentBuffer[this.currentOffset++] & 0xff; // NOSONAR
+				this.available.decrementAndGet();
+				if (this.currentOffset >= this.currentBuffer.length) {
+					this.currentBuffer = null;
+				}
+				return bite;
 			}
-			int bite;
-			bite = this.currentBuffer[this.currentOffset++] & 0xff; // NOSONAR
-			this.available.decrementAndGet();
-			if (this.currentOffset >= this.currentBuffer.length) {
-				this.currentBuffer = null;
+			finally {
+				this.innerLock.unlock();
 			}
-			return bite;
 		}
 
 		@Nullable

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpNioSSLConnection.java

@@ -21,6 +21,8 @@ import java.nio.ByteBuffer;
 import java.nio.channels.SocketChannel;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.net.ssl.SSLEngine;
 import javax.net.ssl.SSLEngineResult;
@@ -51,6 +53,7 @@ import org.springframework.util.Assert;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.2
  *
@@ -67,7 +70,7 @@ public class TcpNioSSLConnection extends TcpNioConnection {
 
 	private final Semaphore semaphore = new Semaphore(0);
 
-	private final Object monitorLock = new Object();
+	private final Lock monitorLock = new ReentrantLock();
 
 	private int handshakeTimeout = DEFAULT_HANDSHAKE_TIMEOUT;
 
@@ -285,12 +288,16 @@ public class TcpNioSSLConnection extends TcpNioConnection {
 
 	@Override
 	protected ChannelOutputStream getChannelOutputStream() {
-		synchronized (this.monitorLock) {
+		this.monitorLock.lock();
+		try {
 			if (this.sslChannelOutputStream == null) {
 				this.sslChannelOutputStream = new SSLChannelOutputStream(super.getChannelOutputStream());
 			}
 			return this.sslChannelOutputStream;
 		}
+		finally {
+			this.monitorLock.unlock();
+		}
 	}
 
 	protected SSLChannelOutputStream getSSLChannelOutputStream() {
@@ -318,6 +325,8 @@ public class TcpNioSSLConnection extends TcpNioConnection {
 	 */
 	final class SSLChannelOutputStream extends ChannelOutputStream {
 
+		private final Lock lock = new ReentrantLock();
+
 		private final ChannelOutputStream channelOutputStream;
 
 		SSLChannelOutputStream(ChannelOutputStream channelOutputStream) {
@@ -331,7 +340,8 @@ public class TcpNioSSLConnection extends TcpNioConnection {
 		 * and multiple writes will be necessary.
 		 */
 		@Override
-		protected synchronized void doWrite(ByteBuffer plainText) throws IOException {
+		protected void doWrite(ByteBuffer plainText) throws IOException {
+			this.lock.lock();
 			try {
 				TcpNioSSLConnection.this.writerActive = true;
 				int remaining = plainText.remaining();
@@ -357,6 +367,7 @@ public class TcpNioSSLConnection extends TcpNioConnection {
 			}
 			finally {
 				TcpNioSSLConnection.this.writerActive = false;
+				this.lock.unlock();
 			}
 		}
 

spring-integration-ip/src/main/java/org/springframework/integration/ip/udp/MulticastReceivingChannelAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,6 +32,7 @@ import org.springframework.messaging.MessagingException;
  * @author Gary Russell
  * @author Marcin Pilaczynski
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
@@ -39,7 +40,6 @@ public class MulticastReceivingChannelAdapter extends UnicastReceivingChannelAda
 
 	private final String group;
 
-
 	/**
 	 * Constructs a MulticastReceivingChannelAdapter that listens for packets on the
 	 * specified multichannel address (group) and port.
@@ -65,24 +65,31 @@ public class MulticastReceivingChannelAdapter extends UnicastReceivingChannelAda
 	}
 
 	@Override
-	public synchronized DatagramSocket getSocket() {
-		if (getTheSocket() == null) {
-			try {
-				int port = getPort();
-				MulticastSocket socket = port == 0 ? new MulticastSocket() : new MulticastSocket(port);
-				String localAddress = getLocalAddress();
-				if (localAddress != null) {
-					socket.setNetworkInterface(NetworkInterface.getByInetAddress(InetAddress.getByName(localAddress)));
+	public DatagramSocket getSocket() {
+		this.lock.lock();
+		try {
+			if (getTheSocket() == null) {
+				try {
+					int port = getPort();
+					MulticastSocket socket = port == 0 ? new MulticastSocket() : new MulticastSocket(port);
+					String localAddress = getLocalAddress();
+					if (localAddress != null) {
+						socket.setNetworkInterface(
+								NetworkInterface.getByInetAddress(InetAddress.getByName(localAddress)));
+					}
+					setSocketAttributes(socket);
+					socket.joinGroup(new InetSocketAddress(this.group, 0), null);
+					setSocket(socket);
+				}
+				catch (IOException e) {
+					throw new MessagingException("failed to create DatagramSocket", e);
 				}
-				setSocketAttributes(socket);
-				socket.joinGroup(new InetSocketAddress(this.group, 0), null);
-				setSocket(socket);
-			}
-			catch (IOException e) {
-				throw new MessagingException("failed to create DatagramSocket", e);
 			}
+			return super.getSocket();
+		}
+		finally {
+			this.lock.unlock();
 		}
-		return super.getSocket();
 	}
 
 }

spring-integration-ip/src/main/java/org/springframework/integration/ip/udp/MulticastSendingMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2020 the original author or authors.
+ * Copyright 2001-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,6 +37,7 @@ import org.springframework.messaging.Message;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
@@ -129,11 +130,17 @@ public class MulticastSendingMessageHandler extends UnicastSendingMessageHandler
 	}
 
 	@Override
-	protected synchronized DatagramSocket getSocket() throws IOException {
-		if (getTheSocket() == null) {
-			createSocket();
+	protected DatagramSocket getSocket() throws IOException {
+		this.lock.lock();
+		try {
+			if (getTheSocket() == null) {
+				createSocket();
+			}
+			return super.getSocket();
+		}
+		finally {
+			this.lock.unlock();
 		}
-		return super.getSocket();
 	}
 
 	private void createSocket() throws IOException {

spring-integration-ip/src/main/java/org/springframework/integration/ip/udp/UnicastReceivingChannelAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,8 @@ import java.net.SocketException;
 import java.net.SocketTimeoutException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.RejectedExecutionException;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -44,6 +46,7 @@ import org.springframework.util.Assert;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
@@ -53,6 +56,8 @@ public class UnicastReceivingChannelAdapter extends AbstractInternetProtocolRece
 
 	private final DatagramPacketMessageMapper mapper = new DatagramPacketMessageMapper();
 
+	protected final Lock lock = new ReentrantLock();
+
 	private DatagramSocket socket;
 
 	private boolean socketExplicitlySet;
@@ -248,27 +253,33 @@ public class UnicastReceivingChannelAdapter extends AbstractInternetProtocolRece
 		return this.socket;
 	}
 
-	public synchronized DatagramSocket getSocket() {
-		if (this.socket == null) {
-			try {
-				DatagramSocket datagramSocket;
-				String localAddress = getLocalAddress();
-				int port = super.getPort();
-				if (localAddress == null) {
-					datagramSocket = port == 0 ? new DatagramSocket() : new DatagramSocket(port);
+	public DatagramSocket getSocket() {
+		this.lock.lock();
+		try {
+			if (this.socket == null) {
+				try {
+					DatagramSocket datagramSocket;
+					String localAddress = getLocalAddress();
+					int port = super.getPort();
+					if (localAddress == null) {
+						datagramSocket = port == 0 ? new DatagramSocket() : new DatagramSocket(port);
+					}
+					else {
+						InetAddress whichNic = InetAddress.getByName(localAddress);
+						datagramSocket = new DatagramSocket(new InetSocketAddress(whichNic, port));
+					}
+					setSocketAttributes(datagramSocket);
+					this.socket = datagramSocket;
 				}
-				else {
-					InetAddress whichNic = InetAddress.getByName(localAddress);
-					datagramSocket = new DatagramSocket(new InetSocketAddress(whichNic, port));
+				catch (IOException e) {
+					throw new MessagingException("failed to create DatagramSocket", e);
 				}
-				setSocketAttributes(datagramSocket);
-				this.socket = datagramSocket;
-			}
-			catch (IOException e) {
-				throw new MessagingException("failed to create DatagramSocket", e);
 			}
+			return this.socket;
+		}
+		finally {
+			this.lock.unlock();
 		}
-		return this.socket;
 	}
 
 	/**

spring-integration-ip/src/main/java/org/springframework/integration/ip/udp/UnicastSendingMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2022 the original author or authors.
+ * Copyright 2001-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,6 +34,8 @@ import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.Expression;
@@ -58,6 +60,7 @@ import org.springframework.util.StringUtils;
  * @author Gary Russell
  * @author Marcin Pilaczynski
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
@@ -66,6 +69,8 @@ public class UnicastSendingMessageHandler extends
 
 	private static final int DEFAULT_ACK_TIMEOUT = 5000;
 
+	protected final Lock lock = new ReentrantLock();
+
 	private final DatagramPacketMessageMapper mapper = new DatagramPacketMessageMapper();
 
 	private final Map<String, CountDownLatch> ackControl = Collections.synchronizedMap(new HashMap<>());
@@ -316,7 +321,8 @@ public class UnicastSendingMessageHandler extends
 
 	public void startAckThread() {
 		if (!this.ackThreadRunning) {
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				if (!this.ackThreadRunning) {
 					try {
 						getSocket();
@@ -334,6 +340,9 @@ public class UnicastSendingMessageHandler extends
 					}
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 	}
 
@@ -386,28 +395,34 @@ public class UnicastSendingMessageHandler extends
 		return this.socket;
 	}
 
-	protected synchronized DatagramSocket getSocket() throws IOException {
-		if (this.socket == null) {
-			if (this.acknowledge) {
-				if (this.localAddress == null) {
-					this.socket = this.ackPort == 0 ? new DatagramSocket() : new DatagramSocket(this.ackPort);
+	protected DatagramSocket getSocket() throws IOException {
+		this.lock.lock();
+		try {
+			if (this.socket == null) {
+				if (this.acknowledge) {
+					if (this.localAddress == null) {
+						this.socket = this.ackPort == 0 ? new DatagramSocket() : new DatagramSocket(this.ackPort);
+					}
+					else {
+						InetAddress whichNic = InetAddress.getByName(this.localAddress);
+						this.socket = new DatagramSocket(new InetSocketAddress(whichNic, this.ackPort));
+					}
+					if (this.soReceiveBufferSize > 0) {
+						this.socket.setReceiveBufferSize(this.soReceiveBufferSize);
+					}
+					logger.debug(() -> "Listening for acks on port: " + getAckPort());
+					updateAckAddress();
 				}
 				else {
-					InetAddress whichNic = InetAddress.getByName(this.localAddress);
-					this.socket = new DatagramSocket(new InetSocketAddress(whichNic, this.ackPort));
+					this.socket = new DatagramSocket();
 				}
-				if (this.soReceiveBufferSize > 0) {
-					this.socket.setReceiveBufferSize(this.soReceiveBufferSize);
-				}
-				logger.debug(() -> "Listening for acks on port: " + getAckPort());
-				updateAckAddress();
+				setSocketAttributes(this.socket);
 			}
-			else {
-				this.socket = new DatagramSocket();
-			}
-			setSocketAttributes(this.socket);
+			return this.socket;
+		}
+		finally {
+			this.lock.unlock();
 		}
-		return this.socket;
 	}
 
 	protected void updateAckAddress() {
@@ -424,8 +439,14 @@ public class UnicastSendingMessageHandler extends
 	}
 
 	@Override
-	public synchronized void setLocalAddress(String localAddress) {
-		this.localAddress = localAddress;
+	public void setLocalAddress(String localAddress) {
+		this.lock.lock();
+		try {
+			this.localAddress = localAddress;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	public void setTaskExecutor(Executor taskExecutor) {

spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/StoredProcExecutor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,8 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.sql.DataSource;
 
@@ -51,6 +53,7 @@ import org.springframework.util.Assert;
  * @author Gunnar Hillert
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
  *
  * @since 2.1
  *
@@ -63,7 +66,7 @@ public class StoredProcExecutor implements BeanFactoryAware, InitializingBean {
 
 	private final DataSource dataSource;
 
-	private final Object jdbcCallOperationsMapMonitor = new Object();
+	private final Lock jdbcCallOperationsMapMonitor = new ReentrantLock();
 
 	private Map<String, RowMapper<?>> returningResultSetRowMappers = new HashMap<>(0);
 
@@ -301,10 +304,14 @@ public class StoredProcExecutor implements BeanFactoryAware, InitializingBean {
 	private SimpleJdbcCallOperations obtainSimpleJdbcCall(String storedProcedureName) {
 		SimpleJdbcCallOperations operations = this.jdbcCallOperationsMap.get(storedProcedureName);
 		if (operations == null) {
-			synchronized (this.jdbcCallOperationsMapMonitor) {
+			this.jdbcCallOperationsMapMonitor.lock();
+			try {
 				operations =
 						this.jdbcCallOperationsMap.computeIfAbsent(storedProcedureName, this::createSimpleJdbcCall);
 			}
+			finally {
+				this.jdbcCallOperationsMapMonitor.unlock();
+			}
 		}
 		return operations;
 	}

spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/channel/PostgresChannelMessageTableSubscriber.java

@@ -26,6 +26,8 @@ import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.postgresql.PGNotification;
 import org.postgresql.jdbc.PgConnection;
@@ -61,6 +63,7 @@ import org.springframework.util.Assert;
  * @author Rafael Winterhalter
  * @author Artem Bilan
  * @author Igor Lovich
+ * @author Christian Tzolov
  *
  * @since 6.0
  */
@@ -68,6 +71,8 @@ public final class PostgresChannelMessageTableSubscriber implements SmartLifecyc
 
 	private static final LogAccessor LOGGER = new LogAccessor(PostgresChannelMessageTableSubscriber.class);
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Map<String, Set<Subscription>> subscriptionsMap = new ConcurrentHashMap<>();
 
 	private final PgConnectionSupplier connectionSupplier;
@@ -111,8 +116,14 @@ public final class PostgresChannelMessageTableSubscriber implements SmartLifecyc
 	 * @deprecated since 6.2 in favor of {@link #setTaskExecutor(AsyncTaskExecutor)}
 	 */
 	@Deprecated(since = "6.2", forRemoval = true)
-	public synchronized void setExecutor(ExecutorService executor) {
-		setTaskExecutor(new TaskExecutorAdapter(executor));
+	public void setExecutor(ExecutorService executor) {
+		this.lock.lock();
+		try {
+			setTaskExecutor(new TaskExecutorAdapter(executor));
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	/**
@@ -149,85 +160,96 @@ public final class PostgresChannelMessageTableSubscriber implements SmartLifecyc
 	}
 
 	@Override
-	public synchronized void start() {
-		if (this.latch.getCount() > 0) {
-			return;
-		}
+	public void start() {
+		this.lock.lock();
+		try {
+			if (this.latch.getCount() > 0) {
+				return;
+			}
 
-		this.latch = new CountDownLatch(1);
+			this.latch = new CountDownLatch(1);
+
+			CountDownLatch startingLatch = new CountDownLatch(1);
+			this.future = this.taskExecutor.submit(() -> {
+				doStart(startingLatch);
+			});
 
-		CountDownLatch startingLatch = new CountDownLatch(1);
-		this.future = this.taskExecutor.submit(() -> {
 			try {
-				while (isActive()) {
-					try {
-						PgConnection conn = this.connectionSupplier.get();
-						try (Statement stmt = conn.createStatement()) {
-							stmt.execute("LISTEN " + this.tablePrefix.toLowerCase() + "channel_message_notify");
-						}
-						catch (Exception ex) {
-							try {
-								conn.close();
-							}
-							catch (Exception suppressed) {
-								ex.addSuppressed(suppressed);
-							}
-							throw ex;
-						}
-						this.subscriptionsMap.values()
-								.forEach(subscriptions -> subscriptions.forEach(Subscription::notifyUpdate));
-						try {
-							this.connection = conn;
-							while (isActive()) {
-								startingLatch.countDown();
+				if (!startingLatch.await(5, TimeUnit.SECONDS)) {
+					throw new IllegalStateException("Failed to start " + this);
+				}
+			}
+			catch (InterruptedException ex) {
+				Thread.currentThread().interrupt();
+				throw new IllegalStateException("Failed to start " + this, ex);
+			}
+		}
+		finally {
+			this.lock.unlock();
+		}
+	}
 
-								PGNotification[] notifications = conn.getNotifications(0);
-								// Unfortunately, there is no good way of interrupting a notification
-								// poll but by closing its connection.
-								if (!isActive()) {
-									return;
-								}
-								if (notifications != null) {
-									for (PGNotification notification : notifications) {
-										String parameter = notification.getParameter();
-										Set<Subscription> subscriptions = this.subscriptionsMap.get(parameter);
-										if (subscriptions == null) {
-											continue;
-										}
-										for (Subscription subscription : subscriptions) {
-											subscription.notifyUpdate();
-										}
+	private void doStart(CountDownLatch startingLatch) {
+		try {
+			while (isActive()) {
+				try {
+					PgConnection conn = this.connectionSupplier.get();
+					try (Statement stmt = conn.createStatement()) {
+						stmt.execute("LISTEN " + this.tablePrefix.toLowerCase() + "channel_message_notify");
+					}
+					catch (Exception ex) {
+						try {
+							conn.close();
+						}
+						catch (Exception suppressed) {
+							ex.addSuppressed(suppressed);
+						}
+						throw ex;
+					}
+					this.subscriptionsMap.values()
+							.forEach(subscriptions -> subscriptions.forEach(Subscription::notifyUpdate));
+					try {
+						this.connection = conn;
+						while (isActive()) {
+							startingLatch.countDown();
+
+							PGNotification[] notifications = conn.getNotifications(0);
+							// Unfortunately, there is no good way of interrupting a notification
+							// poll but by closing its connection.
+							if (!isActive()) {
+								return;
+							}
+							if (notifications != null) {
+								for (PGNotification notification : notifications) {
+									String parameter = notification.getParameter();
+									Set<Subscription> subscriptions = this.subscriptionsMap.get(parameter);
+									if (subscriptions == null) {
+										continue;
+									}
+									for (Subscription subscription : subscriptions) {
+										subscription.notifyUpdate();
 									}
 								}
 							}
 						}
-						finally {
-							conn.close();
-						}
 					}
-					catch (Exception e) {
-						// The getNotifications method does not throw a meaningful message on interruption.
-						// Therefore, we do not log an error, unless it occurred while active.
-						if (isActive()) {
-							LOGGER.error(e, "Failed to poll notifications from Postgres database");
-						}
+					finally {
+						conn.close();
+					}
+				}
+				catch (Exception e) {
+					// The getNotifications method does not throw a meaningful message on interruption.
+					// Therefore, we do not log an error, unless it occurred while active.
+					if (isActive()) {
+						LOGGER.error(e, "Failed to poll notifications from Postgres database");
 					}
 				}
 			}
-			finally {
-				this.latch.countDown();
-			}
-		});
+		}
+		finally {
+			this.latch.countDown();
+		}
 
-		try {
-			if (!startingLatch.await(5, TimeUnit.SECONDS)) {
-				throw new IllegalStateException("Failed to start " + this);
-			}
-		}
-		catch (InterruptedException ex) {
-			Thread.currentThread().interrupt();
-			throw new IllegalStateException("Failed to start " + this, ex);
-		}
 	}
 
 	private boolean isActive() {
@@ -239,25 +261,31 @@ public final class PostgresChannelMessageTableSubscriber implements SmartLifecyc
 	}
 
 	@Override
-	public synchronized void stop() {
-		if (this.future.isDone()) {
-			return;
-		}
-		this.future.cancel(true);
-		PgConnection conn = this.connection;
-		if (conn != null) {
-			try {
-				conn.close();
-			}
-			catch (SQLException ignored) {
-			}
-		}
+	public void stop() {
+		this.lock.lock();
 		try {
-			if (!this.latch.await(5, TimeUnit.SECONDS)) {
-				throw new IllegalStateException("Failed to stop " + this);
+			if (this.future.isDone()) {
+				return;
+			}
+			this.future.cancel(true);
+			PgConnection conn = this.connection;
+			if (conn != null) {
+				try {
+					conn.close();
+				}
+				catch (SQLException ignored) {
+				}
+			}
+			try {
+				if (!this.latch.await(5, TimeUnit.SECONDS)) {
+					throw new IllegalStateException("Failed to stop " + this);
+				}
+			}
+			catch (InterruptedException ignored) {
 			}
 		}
-		catch (InterruptedException ignored) {
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/lock/JdbcLockRegistry.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2022 the original author or authors.
+ * Copyright 2016-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -54,6 +54,7 @@ import org.springframework.util.Assert;
  * @author Olivier Hubaut
  * @author Fran Aranda
  * @author Unseok Kim
+ * @author Christian Tzolov
  *
  * @since 4.3
  */
@@ -63,6 +64,8 @@ public class JdbcLockRegistry implements ExpirableLockRegistry, RenewableLockReg
 
 	private static final int DEFAULT_CAPACITY = 100_000;
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Map<String, JdbcLock> locks =
 			new LinkedHashMap<String, JdbcLock>(16, 0.75F, true) {
 
@@ -111,9 +114,13 @@ public class JdbcLockRegistry implements ExpirableLockRegistry, RenewableLockReg
 	public Lock obtain(Object lockKey) {
 		Assert.isInstanceOf(String.class, lockKey);
 		String path = pathFor((String) lockKey);
-		synchronized (this.locks) {
+		this.lock.lock();
+		try {
 			return this.locks.computeIfAbsent(path, key -> new JdbcLock(this.client, this.idleBetweenTries, key));
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	private String pathFor(String input) {
@@ -123,13 +130,17 @@ public class JdbcLockRegistry implements ExpirableLockRegistry, RenewableLockReg
 	@Override
 	public void expireUnusedOlderThan(long age) {
 		long now = System.currentTimeMillis();
-		synchronized (this.locks) {
+		this.lock.lock();
+		try {
 			this.locks.entrySet()
 					.removeIf(entry -> {
 						JdbcLock lock = entry.getValue();
 						return now - lock.getLastUsed() > age && !lock.isAcquiredInThisProcess();
 					});
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
@@ -137,9 +148,14 @@ public class JdbcLockRegistry implements ExpirableLockRegistry, RenewableLockReg
 		Assert.isInstanceOf(String.class, lockKey);
 		String path = pathFor((String) lockKey);
 		JdbcLock jdbcLock;
-		synchronized (this.locks) {
+		this.lock.lock();
+		try {
 			jdbcLock = this.locks.get(path);
 		}
+		finally {
+			this.lock.unlock();
+		}
+
 		if (jdbcLock == null) {
 			throw new IllegalStateException("Could not found mutex at " + path);
 		}

spring-integration-jms/src/main/java/org/springframework/integration/jms/JmsOutboundGateway.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,6 +29,8 @@ import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import jakarta.jms.Connection;
 import jakarta.jms.ConnectionFactory;
@@ -81,6 +83,7 @@ import org.springframework.util.StringUtils;
  * @author Oleg Zhurakousky
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 		implements ManageableLifecycle, MessageListener {
@@ -90,7 +93,7 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 	 */
 	public static final long DEFAULT_RECEIVE_TIMEOUT = 5000L;
 
-	private final Object initializationMonitor = new Object();
+	private final Lock initializationMonitor = new ReentrantLock();
 
 	private final AtomicLong correlationId = new AtomicLong();
 
@@ -100,10 +103,12 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 
 	private final ConcurrentHashMap<String, TimedReply> earlyOrLateReplies = new ConcurrentHashMap<>();
 
+	private final Lock earlyOrLateRepliesMonitor = new ReentrantLock();
+
 	private final Map<String, CompletableFuture<AbstractIntegrationMessageBuilder<?>>> futures =
 			new ConcurrentHashMap<>();
 
-	private final Object lifeCycleMonitor = new Object();
+	private final Lock lifeCycleMonitor = new ReentrantLock();
 
 	private Destination requestDestination;
 
@@ -512,7 +517,8 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 
 	@Override
 	protected void doInit() {
-		synchronized (this.initializationMonitor) {
+		this.initializationMonitor.lock();
+		try {
 			if (this.initialized) {
 				return;
 			}
@@ -539,6 +545,9 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 			initializeReplyContainer();
 			this.initialized = true;
 		}
+		finally {
+			this.initializationMonitor.unlock();
+		}
 	}
 
 	private void initializeReplyContainer() {
@@ -667,7 +676,8 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 
 	@Override
 	public void start() {
-		synchronized (this.lifeCycleMonitor) {
+		this.lifeCycleMonitor.lock();
+		try {
 			if (!this.active) {
 				if (this.replyContainer != null) {
 					TaskScheduler taskScheduler = getTaskScheduler();
@@ -689,11 +699,15 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 				this.active = true;
 			}
 		}
+		finally {
+			this.lifeCycleMonitor.unlock();
+		}
 	}
 
 	@Override
 	public void stop() {
-		synchronized (this.lifeCycleMonitor) {
+		this.lifeCycleMonitor.lock();
+		try {
 			if (this.replyContainer != null) {
 				this.replyContainer.shutdown();
 				this.wasStopped = true;
@@ -708,6 +722,10 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 			}
 			this.active = false;
 		}
+		finally {
+			this.lifeCycleMonitor.unlock();
+		}
+
 	}
 
 	@Override
@@ -727,7 +745,8 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 			}
 			else {
 				if (this.idleReplyContainerTimeout > 0) {
-					synchronized (this.lifeCycleMonitor) {
+					this.lifeCycleMonitor.lock();
+					try {
 						this.lastSend = System.currentTimeMillis();
 						if (!this.replyContainer.isRunning()) {
 							logger.debug(() -> getComponentName() + ": Starting reply container.");
@@ -738,6 +757,9 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 													Duration.ofMillis(this.idleReplyContainerTimeout / 2));
 						}
 					}
+					finally {
+						this.lifeCycleMonitor.unlock();
+					}
 				}
 				reply = sendAndReceiveWithContainer(requestMessage);
 			}
@@ -1121,13 +1143,17 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 			/*
 			 * Check to see if the reply arrived before we obtained the correlationId
 			 */
-			synchronized (this.earlyOrLateReplies) {
+			this.earlyOrLateRepliesMonitor.lock();
+			try {
 				TimedReply timedReply = this.earlyOrLateReplies.remove(correlation);
 				if (timedReply != null) {
 					logger.debug(() -> "Found early reply with correlationId " + correlationToLog);
 					replyQueue.add(timedReply.getReply());
 				}
 			}
+			finally {
+				this.earlyOrLateRepliesMonitor.unlock();
+			}
 
 			return obtainReplyFromContainer(correlation, replyQueue);
 		}
@@ -1298,13 +1324,17 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 					}
 					throw new IllegalStateException("No sender waiting for reply");
 				}
-				synchronized (this.earlyOrLateReplies) {
+				this.earlyOrLateRepliesMonitor.lock();
+				try {
 					queue = this.replies.get(correlationId);
 					if (queue == null) {
 						logger.debug(() -> "Reply for correlationId " + correlationId + " received early or late");
 						this.earlyOrLateReplies.put(correlationId, new TimedReply(message));
 					}
 				}
+				finally {
+					this.earlyOrLateRepliesMonitor.unlock();
+				}
 			}
 			if (queue != null) {
 				logger.debug(() -> "Received reply with correlationId " + correlationId);
@@ -1466,7 +1496,8 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 
 		@Override
 		public void run() {
-			synchronized (JmsOutboundGateway.this.lifeCycleMonitor) {
+			JmsOutboundGateway.this.lifeCycleMonitor.lock();
+			try {
 				if (System.currentTimeMillis() - JmsOutboundGateway.this.lastSend >
 						JmsOutboundGateway.this.idleReplyContainerTimeout
 						&& JmsOutboundGateway.this.replies.size() == 0 &&
@@ -1478,6 +1509,9 @@ public class JmsOutboundGateway extends AbstractReplyProducingMessageHandler
 					JmsOutboundGateway.this.idleTask = null;
 				}
 			}
+			finally {
+				JmsOutboundGateway.this.lifeCycleMonitor.unlock();
+			}
 		}
 
 	}

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/inbound/KafkaMessageSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2022 the original author or authors.
+ * Copyright 2018-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,6 +30,8 @@ import java.util.Set;
 import java.util.TreeSet;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
@@ -95,6 +97,7 @@ import org.springframework.util.StringUtils;
  * @author Mark Norkin
  * @author Artem Bilan
  * @author Anshul Mehra
+ * @author Christian Tzolov
  *
  * @since 5.4
  *
@@ -111,11 +114,13 @@ public class KafkaMessageSource<K, V> extends AbstractMessageSource<Object> impl
 	 */
 	public static final String REMAINING_RECORDS = KafkaHeaders.PREFIX + "remainingRecords";
 
+	private final Lock lock = new ReentrantLock();
+
 	private final ConsumerFactory<K, V> consumerFactory;
 
 	private final KafkaAckCallbackFactory<K, V> ackCallbackFactory;
 
-	private final Object consumerMonitor = new Object();
+	private final Lock consumerMonitor = new ReentrantLock();
 
 	private final Map<TopicPartition, Set<KafkaAckInfo<K, V>>> inflightRecords = new ConcurrentHashMap<>();
 
@@ -385,31 +390,61 @@ public class KafkaMessageSource<K, V> extends AbstractMessageSource<Object> impl
 	}
 
 	@Override
-	public synchronized boolean isRunning() {
-		return this.running;
+	public boolean isRunning() {
+		this.lock.lock();
+		try {
+			return this.running;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
-	public synchronized void start() {
-		this.running = true;
-		this.stopped = false;
+	public void start() {
+		this.lock.lock();
+		try {
+			this.running = true;
+			this.stopped = false;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
-	public synchronized void stop() {
-		stopConsumer();
-		this.running = false;
-		this.stopped = true;
+	public void stop() {
+		this.lock.lock();
+		try {
+			stopConsumer();
+			this.running = false;
+			this.stopped = true;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
-	public synchronized void pause() {
-		this.pausing = true;
+	public void pause() {
+		this.lock.lock();
+		try {
+			this.pausing = true;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
-	public synchronized void resume() {
-		this.pausing = false;
+	public void resume() {
+		this.lock.lock();
+		try {
+			this.pausing = false;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
@@ -418,35 +453,43 @@ public class KafkaMessageSource<K, V> extends AbstractMessageSource<Object> impl
 	}
 
 	@Override // NOSONAR - not so complex
-	protected synchronized Object doReceive() {
-		if (this.stopped) {
-			this.logger.debug("Message source is stopped; no records will be returned");
-			return null;
-		}
-		if (this.consumer == null) {
-			createConsumer();
-			this.running = true;
-		}
-		if (this.pausing && !this.paused && this.assignedPartitions.size() > 0) {
-			this.consumer.pause(this.assignedPartitions);
-			this.paused = true;
-		}
-		else if (this.paused && !this.pausing) {
-			this.consumer.resume(this.assignedPartitions);
-			this.paused = false;
-		}
-		if (this.paused && this.recordsIterator == null) {
-			this.logger.debug("Consumer is paused; no records will be returned");
-		}
-		ConsumerRecord<K, V> record = pollRecord();
+	protected Object doReceive() {
+		this.lock.lock();
+		try {
 
-		return record != null
-				? recordToMessage(record)
-				: null;
+			if (this.stopped) {
+				this.logger.debug("Message source is stopped; no records will be returned");
+				return null;
+			}
+			if (this.consumer == null) {
+				createConsumer();
+				this.running = true;
+			}
+			if (this.pausing && !this.paused && this.assignedPartitions.size() > 0) {
+				this.consumer.pause(this.assignedPartitions);
+				this.paused = true;
+			}
+			else if (this.paused && !this.pausing) {
+				this.consumer.resume(this.assignedPartitions);
+				this.paused = false;
+			}
+			if (this.paused && this.recordsIterator == null) {
+				this.logger.debug("Consumer is paused; no records will be returned");
+			}
+			ConsumerRecord<K, V> record = pollRecord();
+
+			return record != null
+					? recordToMessage(record)
+					: null;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	protected void createConsumer() {
-		synchronized (this.consumerMonitor) {
+		this.consumerMonitor.lock();
+		try {
 			this.consumer = this.consumerFactory.createConsumer(this.consumerProperties.getGroupId(),
 					this.consumerProperties.getClientId(), null, this.consumerProperties.getKafkaConsumerProperties());
 
@@ -466,6 +509,9 @@ public class KafkaMessageSource<K, V> extends AbstractMessageSource<Object> impl
 						rebalanceCallback);
 			}
 		}
+		finally {
+			this.consumerMonitor.unlock();
+		}
 	}
 
 	private void assignAndSeekPartitions(TopicPartitionOffset[] partitions) {
@@ -522,7 +568,8 @@ public class KafkaMessageSource<K, V> extends AbstractMessageSource<Object> impl
 			return nextRecord();
 		}
 		else {
-			synchronized (this.consumerMonitor) {
+			this.consumerMonitor.lock();
+			try {
 				try {
 					ConsumerRecords<K, V> records = this.consumer
 							.poll(this.assignedPartitions.isEmpty() ? this.assignTimeout : this.pollTimeout);
@@ -545,6 +592,9 @@ public class KafkaMessageSource<K, V> extends AbstractMessageSource<Object> impl
 					return null;
 				}
 			}
+			finally {
+				this.consumerMonitor.unlock();
+			}
 		}
 	}
 
@@ -590,18 +640,28 @@ public class KafkaMessageSource<K, V> extends AbstractMessageSource<Object> impl
 	}
 
 	@Override
-	public synchronized void destroy() {
-		stopConsumer();
+	public void destroy() {
+		this.lock.lock();
+		try {
+			stopConsumer();
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	private void stopConsumer() {
-		synchronized (this.consumerMonitor) {
+		this.consumerMonitor.lock();
+		try {
 			if (this.consumer != null) {
 				this.consumer.close(this.closeTimeout);
 				this.consumer = null;
 				this.assignedPartitions.clear();
 			}
 		}
+		finally {
+			this.consumerMonitor.unlock();
+		}
 	}
 
 	private class IntegrationConsumerRebalanceListener implements ConsumerRebalanceListener {

spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/core/AbstractMqttClientManager.java

@@ -19,6 +19,8 @@ package org.springframework.integration.mqtt.core;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -38,6 +40,7 @@ import org.springframework.util.Assert;
  *
  * @author Artem Vozhdayenko
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 6.0
  */
@@ -47,6 +50,8 @@ public abstract class AbstractMqttClientManager<T, C> implements ClientManager<T
 
 	private static final int DEFAULT_MANAGER_PHASE = 0;
 
+	protected final Lock lock = new ReentrantLock();
+
 	private final Set<ConnectCallback> connectCallbacks = Collections.synchronizedSet(new HashSet<>());
 
 	private final String clientId;
@@ -92,8 +97,14 @@ public abstract class AbstractMqttClientManager<T, C> implements ClientManager<T
 		return this.applicationEventPublisher;
 	}
 
-	protected synchronized void setClient(T client) {
-		this.client = client;
+	protected void setClient(T client) {
+		this.lock.lock();
+		try {
+			this.client = client;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	protected Set<ConnectCallback> getCallbacks() {
@@ -134,8 +145,14 @@ public abstract class AbstractMqttClientManager<T, C> implements ClientManager<T
 	}
 
 	@Override
-	public synchronized T getClient() {
-		return this.client;
+	public T getClient() {
+		this.lock.lock();
+		try {
+			return this.client;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
@@ -177,8 +194,14 @@ public abstract class AbstractMqttClientManager<T, C> implements ClientManager<T
 		return this.connectCallbacks.remove(connectCallback);
 	}
 
-	public synchronized boolean isRunning() {
-		return this.client != null;
+	public boolean isRunning() {
+		this.lock.lock();
+		try {
+			return this.client != null;
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	/**

spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/core/Mqttv3ClientManager.java

@@ -36,6 +36,7 @@ import org.springframework.util.Assert;
  *
  * @author Artem Vozhdayenko
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 6.0
  */
@@ -87,40 +88,46 @@ public class Mqttv3ClientManager
 	}
 
 	@Override
-	public synchronized void start() {
-		var client = getClient();
-		if (client == null) {
-			try {
-				client = createClient();
-			}
-			catch (MqttException e) {
-				throw new IllegalStateException("could not start client manager", e);
-			}
-		}
-		setClient(client);
+	public void start() {
+		this.lock.lock();
 		try {
-			client.connect(this.connectionOptions).waitForCompletion(getCompletionTimeout());
-		}
-		catch (MqttException ex) {
-			// See GH-3822
-			if (this.connectionOptions.isAutomaticReconnect()) {
+			var client = getClient();
+			if (client == null) {
 				try {
-					client.reconnect();
+					client = createClient();
 				}
-				catch (MqttException re) {
-					logger.error("MQTT client failed to connect. Never happens.", re);
+				catch (MqttException e) {
+					throw new IllegalStateException("could not start client manager", e);
 				}
 			}
-			else {
-				var applicationEventPublisher = getApplicationEventPublisher();
-				if (applicationEventPublisher != null) {
-					applicationEventPublisher.publishEvent(new MqttConnectionFailedEvent(this, ex));
+			setClient(client);
+			try {
+				client.connect(this.connectionOptions).waitForCompletion(getCompletionTimeout());
+			}
+			catch (MqttException ex) {
+				// See GH-3822
+				if (this.connectionOptions.isAutomaticReconnect()) {
+					try {
+						client.reconnect();
+					}
+					catch (MqttException re) {
+						logger.error("MQTT client failed to connect. Never happens.", re);
+					}
 				}
 				else {
-					logger.error("Could not start client manager, client_id=" + getClientId(), ex);
+					var applicationEventPublisher = getApplicationEventPublisher();
+					if (applicationEventPublisher != null) {
+						applicationEventPublisher.publishEvent(new MqttConnectionFailedEvent(this, ex));
+					}
+					else {
+						logger.error("Could not start client manager, client_id=" + getClientId(), ex);
+					}
 				}
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	private IMqttAsyncClient createClient() throws MqttException {
@@ -133,31 +140,43 @@ public class Mqttv3ClientManager
 	}
 
 	@Override
-	public synchronized void stop() {
-		var client = getClient();
-		if (client == null) {
-			return;
-		}
+	public void stop() {
+		this.lock.lock();
 		try {
-			client.disconnectForcibly(getDisconnectCompletionTimeout());
-		}
-		catch (MqttException e) {
-			logger.error("Could not disconnect from the client", e);
-		}
-		finally {
+			var client = getClient();
+			if (client == null) {
+				return;
+			}
 			try {
-				client.close();
+				client.disconnectForcibly(getDisconnectCompletionTimeout());
 			}
 			catch (MqttException e) {
-				logger.error("Could not close the client", e);
+				logger.error("Could not disconnect from the client", e);
 			}
-			setClient(null);
+			finally {
+				try {
+					client.close();
+				}
+				catch (MqttException e) {
+					logger.error("Could not close the client", e);
+				}
+				setClient(null);
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 
 	@Override
-	public synchronized void connectionLost(Throwable cause) {
-		logger.error("Connection lost, client_id=" + getClientId(), cause);
+	public void connectionLost(Throwable cause) {
+		this.lock.lock();
+		try {
+			logger.error("Connection lost, client_id=" + getClientId(), cause);
+		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override

spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/core/Mqttv5ClientManager.java

@@ -38,6 +38,7 @@ import org.springframework.util.Assert;
  *
  * @author Artem Vozhdayenko
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 6.0
  */
@@ -89,39 +90,45 @@ public class Mqttv5ClientManager
 	}
 
 	@Override
-	public synchronized void start() {
-		var client = getClient();
-		if (client == null) {
-			try {
-				client = createClient();
-			}
-			catch (MqttException e) {
-				throw new IllegalStateException("Could not start client manager", e);
-			}
-		}
-		setClient(client);
+	public void start() {
+		this.lock.lock();
 		try {
-			client.connect(this.connectionOptions).waitForCompletion(getCompletionTimeout());
-		}
-		catch (MqttException ex) {
-			if (this.connectionOptions.isAutomaticReconnect()) {
+			var client = getClient();
+			if (client == null) {
 				try {
-					client.reconnect();
+					client = createClient();
 				}
-				catch (MqttException re) {
-					logger.error("MQTT client failed to connect. Never happens.", re);
+				catch (MqttException e) {
+					throw new IllegalStateException("Could not start client manager", e);
 				}
 			}
-			else {
-				var applicationEventPublisher = getApplicationEventPublisher();
-				if (applicationEventPublisher != null) {
-					applicationEventPublisher.publishEvent(new MqttConnectionFailedEvent(this, ex));
+			setClient(client);
+			try {
+				client.connect(this.connectionOptions).waitForCompletion(getCompletionTimeout());
+			}
+			catch (MqttException ex) {
+				if (this.connectionOptions.isAutomaticReconnect()) {
+					try {
+						client.reconnect();
+					}
+					catch (MqttException re) {
+						logger.error("MQTT client failed to connect. Never happens.", re);
+					}
 				}
 				else {
-					logger.error("Could not start client manager, client_id=" + getClientId(), ex);
+					var applicationEventPublisher = getApplicationEventPublisher();
+					if (applicationEventPublisher != null) {
+						applicationEventPublisher.publishEvent(new MqttConnectionFailedEvent(this, ex));
+					}
+					else {
+						logger.error("Could not start client manager, client_id=" + getClientId(), ex);
+					}
 				}
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	private MqttAsyncClient createClient() throws MqttException {
@@ -134,26 +141,32 @@ public class Mqttv5ClientManager
 	}
 
 	@Override
-	public synchronized void stop() {
-		var client = getClient();
-		if (client == null) {
-			return;
-		}
-
+	public void stop() {
+		this.lock.lock();
 		try {
-			client.disconnectForcibly(getDisconnectCompletionTimeout());
-		}
-		catch (MqttException e) {
-			logger.error("Could not disconnect from the client", e);
-		}
-		finally {
+			var client = getClient();
+			if (client == null) {
+				return;
+			}
+
 			try {
-				client.close();
+				client.disconnectForcibly(getDisconnectCompletionTimeout());
 			}
 			catch (MqttException e) {
-				logger.error("Could not close the client", e);
+				logger.error("Could not disconnect from the client", e);
 			}
-			setClient(null);
+			finally {
+				try {
+					client.close();
+				}
+				catch (MqttException e) {
+					logger.error("Could not close the client", e);
+				}
+				setClient(null);
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/inbound/MqttPahoMessageDrivenChannelAdapter.java

@@ -17,6 +17,8 @@
 package org.springframework.integration.mqtt.inbound;
 
 import java.util.Arrays;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Stream;
 
 import org.eclipse.paho.client.mqttv3.IMqttAsyncClient;
@@ -64,6 +66,8 @@ public class MqttPahoMessageDrivenChannelAdapter
 		extends AbstractMqttMessageDrivenChannelAdapter<IMqttAsyncClient, MqttConnectOptions>
 		implements MqttCallbackExtended, MqttPahoComponent {
 
+	private final Lock lock =  new ReentrantLock();
+
 	private final MqttPahoClientFactory clientFactory;
 
 	private volatile IMqttAsyncClient client;
@@ -179,46 +183,58 @@ public class MqttPahoMessageDrivenChannelAdapter
 	}
 
 	@SuppressWarnings("deprecation")
-	private synchronized void connect() throws MqttException {
-		MqttConnectOptions connectionOptions = this.clientFactory.getConnectionOptions();
-		var clientManager = getClientManager();
-		if (clientManager == null) {
-			Assert.state(getUrl() != null || connectionOptions.getServerURIs() != null,
-					"If no 'url' provided, connectionOptions.getServerURIs() must not be null");
-			this.client = this.clientFactory.getAsyncClientInstance(getUrl(), getClientId());
-			this.client.setCallback(this);
-			this.client.connect(connectionOptions).waitForCompletion(getCompletionTimeout());
-			this.client.setManualAcks(isManualAcks());
+	private void connect() throws MqttException {
+		this.lock.lock();
+		try {
+			MqttConnectOptions connectionOptions = this.clientFactory.getConnectionOptions();
+			var clientManager = getClientManager();
+			if (clientManager == null) {
+				Assert.state(getUrl() != null || connectionOptions.getServerURIs() != null,
+						"If no 'url' provided, connectionOptions.getServerURIs() must not be null");
+				this.client = this.clientFactory.getAsyncClientInstance(getUrl(), getClientId());
+				this.client.setCallback(this);
+				this.client.connect(connectionOptions).waitForCompletion(getCompletionTimeout());
+				this.client.setManualAcks(isManualAcks());
+			}
+			else {
+				this.client = clientManager.getClient();
+			}
 		}
-		else {
-			this.client = clientManager.getClient();
+		finally {
+			this.lock.unlock();
 		}
 	}
 
 	@Override
-	protected synchronized void doStop() {
-		this.readyToSubscribeOnStart = false;
+	protected void doStop() {
+		this.lock.lock();
 		try {
-			if (this.clientFactory.getConnectionOptions().isCleanSession()) {
-				this.client.unsubscribe(getTopic());
-				// Have to re-subscribe on next start if connection is not lost.
-				this.readyToSubscribeOnStart = true;
+			this.readyToSubscribeOnStart = false;
+			try {
+				if (this.clientFactory.getConnectionOptions().isCleanSession()) {
+					this.client.unsubscribe(getTopic());
+					// Have to re-subscribe on next start if connection is not lost.
+					this.readyToSubscribeOnStart = true;
 
+				}
+			}
+			catch (MqttException ex1) {
+				logger.error(ex1, "Exception while unsubscribing");
+			}
+
+			if (getClientManager() != null) {
+				return;
+			}
+
+			try {
+				this.client.disconnectForcibly(getDisconnectCompletionTimeout());
+			}
+			catch (MqttException ex) {
+				logger.error(ex, "Exception while disconnecting");
 			}
 		}
-		catch (MqttException ex1) {
-			logger.error(ex1, "Exception while unsubscribing");
-		}
-
-		if (getClientManager() != null) {
-			return;
-		}
-
-		try {
-			this.client.disconnectForcibly(getDisconnectCompletionTimeout());
-		}
-		catch (MqttException ex) {
-			logger.error(ex, "Exception while disconnecting");
+		finally {
+			this.lock.unlock();
 		}
 	}
 
@@ -322,17 +338,23 @@ public class MqttPahoMessageDrivenChannelAdapter
 	}
 
 	@Override
-	public synchronized void connectionLost(Throwable cause) {
-		if (isRunning()) {
-			this.logger.error(() -> "Lost connection: " + cause.getMessage());
-			ApplicationEventPublisher applicationEventPublisher = getApplicationEventPublisher();
-			if (applicationEventPublisher != null) {
-				applicationEventPublisher.publishEvent(new MqttConnectionFailedEvent(this, cause));
+	public void connectionLost(Throwable cause) {
+		this.lock.lock();
+		try {
+			if (isRunning()) {
+				this.logger.error(() -> "Lost connection: " + cause.getMessage());
+				ApplicationEventPublisher applicationEventPublisher = getApplicationEventPublisher();
+				if (applicationEventPublisher != null) {
+					applicationEventPublisher.publishEvent(new MqttConnectionFailedEvent(this, cause));
+				}
+			}
+			else {
+				// The 'connectComplete()' re-subscribes or sets this flag otherwise.
+				this.readyToSubscribeOnStart = false;
 			}
 		}
-		else {
-			// The 'connectComplete()' re-subscribes or sets this flag otherwise.
-			this.readyToSubscribeOnStart = false;
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/inbound/Mqttv5PahoMessageDrivenChannelAdapter.java

@@ -18,6 +18,8 @@ package org.springframework.integration.mqtt.inbound;
 
 import java.util.Arrays;
 import java.util.Map;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.IntStream;
 
 import org.eclipse.paho.mqttv5.client.IMqttAsyncClient;
@@ -81,6 +83,8 @@ public class Mqttv5PahoMessageDrivenChannelAdapter
 		extends AbstractMqttMessageDrivenChannelAdapter<IMqttAsyncClient, MqttConnectionOptions>
 		implements MqttCallback, MqttComponent<MqttConnectionOptions> {
 
+	private final Lock lock =  new ReentrantLock();
+
 	private final MqttConnectionOptions connectionOptions;
 
 	private IMqttAsyncClient mqttClient;
@@ -211,13 +215,19 @@ public class Mqttv5PahoMessageDrivenChannelAdapter
 		}
 	}
 
-	private synchronized void connect() throws MqttException {
-		var clientManager = getClientManager();
-		if (clientManager == null) {
-			this.mqttClient.connect(this.connectionOptions).waitForCompletion(getCompletionTimeout());
+	private void connect() throws MqttException {
+		this.lock.lock();
+		try {
+			var clientManager = getClientManager();
+			if (clientManager == null) {
+				this.mqttClient.connect(this.connectionOptions).waitForCompletion(getCompletionTimeout());
+			}
+			else {
+				this.mqttClient = clientManager.getClient();
+			}
 		}
-		else {
-			this.mqttClient = clientManager.getClient();
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/outbound/AbstractMqttMessageHandler.java

@@ -17,6 +17,8 @@
 package org.springframework.integration.mqtt.outbound;
 
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.context.ApplicationEventPublisher;
@@ -63,6 +65,8 @@ public abstract class AbstractMqttMessageHandler<T, C> extends AbstractMessageHa
 	private static final MessageProcessor<String> DEFAULT_TOPIC_PROCESSOR =
 			(message) -> message.getHeaders().get(MqttHeaders.TOPIC, String.class);
 
+	protected final Lock lock = new ReentrantLock();
+
 	private final AtomicBoolean running = new AtomicBoolean();
 
 	private final String url;

spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/outbound/MqttPahoMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -50,6 +50,7 @@ import org.springframework.util.Assert;
  * @author Gary Russell
  * @author Artem Bilan
  * @author Artem Vozhdayenko
+ * @author Christian Tzolov
  *
  * @since 4.0
  *
@@ -184,41 +185,47 @@ public class MqttPahoMessageHandler extends AbstractMqttMessageHandler<IMqttAsyn
 		}
 	}
 
-	private synchronized IMqttAsyncClient checkConnection() throws MqttException {
-		var theClientManager = getClientManager();
-		if (theClientManager != null) {
-			return theClientManager.getClient();
-		}
+	private IMqttAsyncClient checkConnection() throws MqttException {
+		this.lock.lock();
+		try {
+			var theClientManager = getClientManager();
+			if (theClientManager != null) {
+				return theClientManager.getClient();
+			}
 
-		if (this.client != null && !this.client.isConnected()) {
-			this.client.setCallback(null);
-			this.client.close();
-			this.client = null;
-		}
-		if (this.client == null) {
-			try {
-				MqttConnectOptions connectionOptions = this.clientFactory.getConnectionOptions();
-				Assert.state(this.getUrl() != null || connectionOptions.getServerURIs() != null,
-						"If no 'url' provided, connectionOptions.getServerURIs() must not be null");
-				this.client = this.clientFactory.getAsyncClientInstance(this.getUrl(), this.getClientId());
-				incrementClientInstance();
-				this.client.setCallback(this);
-				this.client.connect(connectionOptions).waitForCompletion(getCompletionTimeout());
-				logger.debug("Client connected");
+			if (this.client != null && !this.client.isConnected()) {
+				this.client.setCallback(null);
+				this.client.close();
+				this.client = null;
 			}
-			catch (MqttException e) {
-				if (this.client != null) {
-					this.client.close();
-					this.client = null;
+			if (this.client == null) {
+				try {
+					MqttConnectOptions connectionOptions = this.clientFactory.getConnectionOptions();
+					Assert.state(this.getUrl() != null || connectionOptions.getServerURIs() != null,
+							"If no 'url' provided, connectionOptions.getServerURIs() must not be null");
+					this.client = this.clientFactory.getAsyncClientInstance(this.getUrl(), this.getClientId());
+					incrementClientInstance();
+					this.client.setCallback(this);
+					this.client.connect(connectionOptions).waitForCompletion(getCompletionTimeout());
+					logger.debug("Client connected");
 				}
-				ApplicationEventPublisher applicationEventPublisher = getApplicationEventPublisher();
-				if (applicationEventPublisher != null) {
-					applicationEventPublisher.publishEvent(new MqttConnectionFailedEvent(this, e));
+				catch (MqttException e) {
+					if (this.client != null) {
+						this.client.close();
+						this.client = null;
+					}
+					ApplicationEventPublisher applicationEventPublisher = getApplicationEventPublisher();
+					if (applicationEventPublisher != null) {
+						applicationEventPublisher.publishEvent(new MqttConnectionFailedEvent(this, e));
+					}
+					throw new MessagingException("Failed to connect", e);
 				}
-				throw new MessagingException("Failed to connect", e);
 			}
+			return this.client;
+		}
+		finally {
+			this.lock.unlock();
 		}
-		return this.client;
 	}
 
 	@Override
@@ -252,22 +259,28 @@ public class MqttPahoMessageHandler extends AbstractMqttMessageHandler<IMqttAsyn
 	}
 
 	@Override
-	public synchronized void connectionLost(Throwable cause) {
-		logger.error("Lost connection; will attempt reconnect on next request");
-		if (this.client != null) {
-			try {
-				this.client.setCallback(null);
-				this.client.close();
-			}
-			catch (MqttException e) {
-				// NOSONAR
-			}
-			this.client = null;
-			ApplicationEventPublisher applicationEventPublisher = getApplicationEventPublisher();
-			if (applicationEventPublisher != null) {
-				applicationEventPublisher.publishEvent(new MqttConnectionFailedEvent(this, cause));
+	public void connectionLost(Throwable cause) {
+		this.lock.lock();
+		try {
+			logger.error("Lost connection; will attempt reconnect on next request");
+			if (this.client != null) {
+				try {
+					this.client.setCallback(null);
+					this.client.close();
+				}
+				catch (MqttException e) {
+					// NOSONAR
+				}
+				this.client = null;
+				ApplicationEventPublisher applicationEventPublisher = getApplicationEventPublisher();
+				if (applicationEventPublisher != null) {
+					applicationEventPublisher.publishEvent(new MqttConnectionFailedEvent(this, cause));
+				}
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override

spring-integration-redis/src/main/java/org/springframework/integration/redis/util/RedisLockRegistry.java

@@ -82,6 +82,7 @@ import org.springframework.util.ReflectionUtils;
  * @author Vedran Pavic
  * @author Unseok Kim
  * @author Anton Gabov
+ * @author Christian Tzolov
  *
  * @since 4.0
  *
@@ -94,6 +95,8 @@ public final class RedisLockRegistry implements ExpirableLockRegistry, Disposabl
 
 	private static final int DEFAULT_CAPACITY = 100_000;
 
+	private final Lock lock = new ReentrantLock();
+
 	private final Map<String, RedisLock> locks =
 			new LinkedHashMap<String, RedisLock>(16, 0.75F, true) {
 
@@ -224,15 +227,20 @@ public final class RedisLockRegistry implements ExpirableLockRegistry, Disposabl
 	public Lock obtain(Object lockKey) {
 		Assert.isInstanceOf(String.class, lockKey);
 		String path = (String) lockKey;
-		synchronized (this.locks) {
+		this.lock.lock();
+		try {
 			return this.locks.computeIfAbsent(path, getRedisLockConstructor(this.redisLockType));
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
 	public void expireUnusedOlderThan(long age) {
 		long now = System.currentTimeMillis();
-		synchronized (this.locks) {
+		this.lock.lock();
+		try {
 			this.locks.entrySet()
 					.removeIf(entry -> {
 						RedisLock lock = entry.getValue();
@@ -243,6 +251,9 @@ public final class RedisLockRegistry implements ExpirableLockRegistry, Disposabl
 								&& !lock.isAcquiredInThisProcess();
 					});
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
@@ -631,7 +642,8 @@ public final class RedisLockRegistry implements ExpirableLockRegistry, Disposabl
 		}
 
 		private void runRedisMessageListenerContainer() {
-			synchronized (RedisLockRegistry.this.locks) {
+			RedisLockRegistry.this.lock.tryLock();
+			try {
 				if (!(RedisLockRegistry.this.isRunningRedisMessageListenerContainer
 						&& RedisLockRegistry.this.redisMessageListenerContainer != null
 						&& RedisLockRegistry.this.redisMessageListenerContainer.isRunning())) {
@@ -645,6 +657,9 @@ public final class RedisLockRegistry implements ExpirableLockRegistry, Disposabl
 					RedisLockRegistry.this.isRunningRedisMessageListenerContainer = true;
 				}
 			}
+			finally {
+				RedisLockRegistry.this.lock.unlock();
+			}
 		}
 
 		private static final class RedisUnLockNotifyMessageListener implements MessageListener {

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/session/DefaultSftpSessionFactory.java

@@ -62,11 +62,14 @@ import org.springframework.util.Assert;
  * @author Artem Bilan
  * @author Krzysztof Debski
  * @author Auke Zaaiman
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
 public class DefaultSftpSessionFactory implements SessionFactory<SftpClient.DirEntry>, SharedSessionCapable {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final SshClient sshClient;
 
 	private volatile boolean initialized;
@@ -323,12 +326,16 @@ public class DefaultSftpSessionFactory implements SessionFactory<SftpClient.DirE
 
 	private void initClient() throws IOException {
 		if (!this.initialized) {
-			synchronized (this) {
+			this.lock.lock();
+			try {
 				if (!this.initialized) {
 					doInitClient();
 					this.initialized = true;
 				}
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 	}
 

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/session/SftpSession.java

@@ -22,6 +22,8 @@ import java.io.OutputStream;
 import java.io.UncheckedIOException;
 import java.net.SocketAddress;
 import java.time.Duration;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
 
@@ -46,11 +48,14 @@ import org.springframework.util.StringUtils;
  * @author Oleg Zhurakousky
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 2.0
  */
 public class SftpSession implements Session<SftpClient.DirEntry> {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final SftpClient sftpClient;
 
 	public SftpSession(SftpClient sftpClient) {
@@ -122,15 +127,20 @@ public class SftpSession implements Session<SftpClient.DirEntry> {
 
 	@Override
 	public void write(InputStream inputStream, String destination) throws IOException {
-		synchronized (this.sftpClient) {
+		this.lock.lock();
+		try {
 			OutputStream outputStream = this.sftpClient.write(destination);
 			FileCopyUtils.copy(inputStream, outputStream);
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override
 	public void append(InputStream inputStream, String destination) throws IOException {
-		synchronized (this.sftpClient) {
+		this.lock.lock();
+		try {
 			OutputStream outputStream =
 					this.sftpClient.write(destination,
 							SftpClient.OpenMode.Create,
@@ -138,6 +148,9 @@ public class SftpSession implements Session<SftpClient.DirEntry> {
 							SftpClient.OpenMode.Append);
 			FileCopyUtils.copy(inputStream, outputStream);
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override

spring-integration-smb/src/main/java/org/springframework/integration/smb/session/SmbShare.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,8 @@ package org.springframework.integration.smb.session;
 import java.io.IOException;
 import java.util.Properties;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import jcifs.CIFSContext;
 import jcifs.CIFSException;
@@ -41,6 +43,7 @@ import org.springframework.util.StringUtils;
  * @author Gregory Bragg
  * @author Adam Jones
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 6.0
  */
@@ -48,6 +51,8 @@ public class SmbShare extends SmbFile {
 
 	private static final Log logger = LogFactory.getLog(SmbShare.class);
 
+	private final Lock lock = new ReentrantLock();
+
 	private final AtomicBoolean open = new AtomicBoolean(false);
 
 	private final AtomicBoolean closeContext = new AtomicBoolean(false);
@@ -126,17 +131,23 @@ public class SmbShare extends SmbFile {
 	}
 
 	@Override
-	public synchronized void close() {
-		this.open.set(false);
-		if (this.closeContext.get()) {
-			try {
-				getContext().close();
-			}
-			catch (CIFSException e) {
-				logger.error("Unable to close share: " + this);
+	public void close() {
+		this.lock.lock();
+		try {
+			this.open.set(false);
+			if (this.closeContext.get()) {
+				try {
+					getContext().close();
+				}
+				catch (CIFSException e) {
+					logger.error("Unable to close share: " + this);
+				}
 			}
+			super.close();
+		}
+		finally {
+			this.lock.unlock();
 		}
-		super.close();
 	}
 
 	/**

spring-integration-stomp/src/main/java/org/springframework/integration/stomp/AbstractStompSessionManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2022 the original author or authors.
+ * Copyright 2015-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,8 @@ import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.BiConsumer;
 
 import org.apache.commons.logging.Log;
@@ -66,6 +68,7 @@ import org.springframework.util.concurrent.ListenableFuture;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
  *
  * @since 4.2
  */
@@ -80,7 +83,9 @@ public abstract class AbstractStompSessionManager implements StompSessionManager
 
 	private final CompositeStompSessionHandler compositeStompSessionHandler = new CompositeStompSessionHandler();
 
-	private final Object lifecycleMonitor = new Object();
+	private final Lock lifecycleMonitor = new ReentrantLock();
+
+	private final Lock lock = new ReentrantLock();
 
 	private final AtomicInteger epoch = new AtomicInteger();
 
@@ -177,41 +182,47 @@ public abstract class AbstractStompSessionManager implements StompSessionManager
 		return this.phase;
 	}
 
-	private synchronized void connect() {
-		if (this.connecting || this.connected) {
-			this.logger.debug("Aborting connect; another thread is connecting.");
-			return;
-		}
-		final int currentEpoch = this.epoch.get();
-		this.connecting = true;
-		if (this.logger.isDebugEnabled()) {
-			this.logger.debug("Connecting " + this);
-		}
+	private void connect() {
+		this.lock.lock();
 		try {
-			this.stompSessionFuture = doConnect(this.compositeStompSessionHandler);
-		}
-		catch (Exception e) {
-			if (currentEpoch == this.epoch.get()) {
-				scheduleReconnect(e);
+			if (this.connecting || this.connected) {
+				this.logger.debug("Aborting connect; another thread is connecting.");
+				return;
 			}
-			else {
-				this.logger.error("STOMP doConnect() error for " + this, e);
+			final int currentEpoch = this.epoch.get();
+			this.connecting = true;
+			if (this.logger.isDebugEnabled()) {
+				this.logger.debug("Connecting " + this);
 			}
-			return;
-		}
-		CountDownLatch connectLatch = addStompSessionCallback(currentEpoch);
-
-		try {
-			if (!connectLatch.await(30, TimeUnit.SECONDS)) { // NOSONAR magic number
-				this.logger.error("No response to connection attempt");
+			try {
+				this.stompSessionFuture = doConnect(this.compositeStompSessionHandler);
+			}
+			catch (Exception e) {
 				if (currentEpoch == this.epoch.get()) {
-					scheduleReconnect(null);
+					scheduleReconnect(e);
+				}
+				else {
+					this.logger.error("STOMP doConnect() error for " + this, e);
+				}
+				return;
+			}
+			CountDownLatch connectLatch = addStompSessionCallback(currentEpoch);
+
+			try {
+				if (!connectLatch.await(30, TimeUnit.SECONDS)) { // NOSONAR magic number
+					this.logger.error("No response to connection attempt");
+					if (currentEpoch == this.epoch.get()) {
+						scheduleReconnect(null);
+					}
 				}
 			}
+			catch (InterruptedException e1) {
+				this.logger.error("Interrupted while waiting for connection attempt");
+				Thread.currentThread().interrupt();
+			}
 		}
-		catch (InterruptedException e1) {
-			this.logger.error("Interrupted while waiting for connection attempt");
-			Thread.currentThread().interrupt();
+		finally {
+			this.lock.unlock();
 		}
 	}
 
@@ -294,7 +305,8 @@ public abstract class AbstractStompSessionManager implements StompSessionManager
 
 	@Override
 	public void start() {
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (!isRunning()) {
 				if (this.logger.isInfoEnabled()) {
 					this.logger.info("Starting " + this);
@@ -303,11 +315,15 @@ public abstract class AbstractStompSessionManager implements StompSessionManager
 				this.running = true;
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 	}
 
 	@Override
 	public void stop() {
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (isRunning()) {
 				this.running = false;
 				if (this.logger.isInfoEnabled()) {
@@ -316,6 +332,9 @@ public abstract class AbstractStompSessionManager implements StompSessionManager
 				destroy();
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 	}
 
 	@Override
@@ -355,18 +374,24 @@ public abstract class AbstractStompSessionManager implements StompSessionManager
 
 		private final List<StompSessionHandler> delegates = Collections.synchronizedList(new ArrayList<>());
 
+		private final Lock delegatesMonitor = new ReentrantLock();
+
 		private volatile StompSession session;
 
 		CompositeStompSessionHandler() {
 		}
 
 		void addHandler(StompSessionHandler delegate) {
-			synchronized (this.delegates) {
+			this.delegatesMonitor.lock();
+			try {
 				if (this.session != null) {
 					delegate.afterConnected(this.session, getConnectHeaders());
 				}
 				this.delegates.add(delegate);
 			}
+			finally {
+				this.delegatesMonitor.unlock();
+			}
 		}
 
 		void removeHandler(StompSessionHandler delegate) {
@@ -375,23 +400,31 @@ public abstract class AbstractStompSessionManager implements StompSessionManager
 
 		@Override
 		public void afterConnected(StompSession session, StompHeaders connectedHeaders) {
-			synchronized (this.delegates) {
+			this.delegatesMonitor.lock();
+			try {
 				this.session = session;
 				for (StompSessionHandler delegate : this.delegates) {
 					delegate.afterConnected(session, connectedHeaders);
 				}
 			}
+			finally {
+				this.delegatesMonitor.unlock();
+			}
 		}
 
 		@Override
 		public void handleException(StompSession session, @Nullable StompCommand command, StompHeaders headers,
 				byte[] payload, Throwable exception) {
 
-			synchronized (this.delegates) {
+			this.delegatesMonitor.lock();
+			try {
 				for (StompSessionHandler delegate : this.delegates) {
 					delegate.handleException(session, command, headers, payload, exception);
 				}
 			}
+			finally {
+				this.delegatesMonitor.unlock();
+			}
 		}
 
 		@Override
@@ -400,20 +433,28 @@ public abstract class AbstractStompSessionManager implements StompSessionManager
 					exception);
 			this.session = null;
 			scheduleReconnect(exception);
-			synchronized (this.delegates) {
+			this.delegatesMonitor.lock();
+			try {
 				for (StompSessionHandler delegate : this.delegates) {
 					delegate.handleTransportError(session, exception);
 				}
 			}
+			finally {
+				this.delegatesMonitor.unlock();
+			}
 		}
 
 		@Override
 		public void handleFrame(StompHeaders headers, Object payload) {
-			synchronized (this.delegates) {
+			this.delegatesMonitor.lock();
+			try {
 				for (StompSessionHandler delegate : this.delegates) {
 					delegate.handleFrame(headers, payload);
 				}
 			}
+			finally {
+				this.delegatesMonitor.unlock();
+			}
 		}
 
 	}

spring-integration-stomp/src/main/java/org/springframework/integration/stomp/outbound/StompMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2020 the original author or authors.
+ * Copyright 2015-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@ package org.springframework.integration.stomp.outbound;
 
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.ApplicationEventPublisherAware;
@@ -51,6 +53,7 @@ import org.springframework.util.Assert;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
  *
  * @since 4.2
  */
@@ -59,6 +62,8 @@ public class StompMessageHandler extends AbstractMessageHandler
 
 	private static final int DEFAULT_CONNECT_TIMEOUT = 3000;
 
+	private final Lock lock = new ReentrantLock();
+
 	private final StompSessionHandler sessionHandler = new IntegrationOutboundStompSessionHandler();
 
 	private final StompSessionManager stompSessionManager;
@@ -178,7 +183,8 @@ public class StompMessageHandler extends AbstractMessageHandler
 	}
 
 	private void connectIfNecessary() throws InterruptedException {
-		synchronized (this.connectSemaphore) {
+		this.lock.lock();
+		try {
 			if (this.stompSession == null || !this.stompSessionManager.isConnected()) {
 				this.stompSessionManager.disconnect(this.sessionHandler);
 				this.stompSessionManager.connect(this.sessionHandler);
@@ -199,6 +205,9 @@ public class StompMessageHandler extends AbstractMessageHandler
 				}
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override

spring-integration-stomp/src/test/java/org/springframework/integration/stomp/inbound/StompInboundChannelAdapterWebSocketIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2022 the original author or authors.
+ * Copyright 2015-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -247,7 +247,8 @@ public class StompInboundChannelAdapterWebSocketIntegrationTests {
 		}
 
 		@Bean
-		public WebSocketStompClient stompClient(TaskScheduler taskScheduler) {
+		public WebSocketStompClient stompClient(
+			@Qualifier("taskScheduler") TaskScheduler taskScheduler) {
 			WebSocketStompClient webSocketStompClient = new WebSocketStompClient(webSocketClient());
 			webSocketStompClient.setMessageConverter(new MappingJackson2MessageConverter());
 			webSocketStompClient.setTaskScheduler(taskScheduler);
@@ -347,6 +348,7 @@ public class StompInboundChannelAdapterWebSocketIntegrationTests {
 		//SimpleBrokerMessageHandler doesn't support RECEIPT frame, hence we emulate it this way
 		@Bean
 		public ApplicationListener<SessionSubscribeEvent> webSocketEventListener(
+				@Qualifier("clientOutboundChannel")
 				final AbstractSubscribableChannel clientOutboundChannel) {
 			return event -> {
 				Message<byte[]> message = event.getMessage();

spring-integration-stream/src/main/java/org/springframework/integration/stream/ByteStreamReadingMessageSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,8 @@ package org.springframework.integration.stream;
 import java.io.BufferedInputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.integration.endpoint.AbstractMessageSource;
 import org.springframework.messaging.MessagingException;
@@ -28,9 +30,12 @@ import org.springframework.messaging.MessagingException;
  *
  * @author Mark Fisher
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class ByteStreamReadingMessageSource extends AbstractMessageSource<byte[]> {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final BufferedInputStream stream;
 
 	private int bytesPerMessage = 1024; // NOSONAR magic number
@@ -73,13 +78,17 @@ public class ByteStreamReadingMessageSource extends AbstractMessageSource<byte[]
 		try {
 			byte[] bytes;
 			int bytesRead = 0;
-			synchronized (this.stream) {
+			this.lock.lock();
+			try {
 				if (this.stream.available() == 0) {
 					return null;
 				}
 				bytes = new byte[this.bytesPerMessage];
 				bytesRead = this.stream.read(bytes, 0, bytes.length);
 			}
+			finally {
+				this.lock.unlock();
+			}
 			if (bytesRead <= 0) {
 				return null;
 			}

spring-integration-stream/src/main/java/org/springframework/integration/stream/CharacterStreamReadingMessageSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@ import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.Reader;
 import java.io.UnsupportedEncodingException;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.ApplicationEventPublisherAware;
@@ -34,10 +36,13 @@ import org.springframework.util.Assert;
  * @author Mark Fisher
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class CharacterStreamReadingMessageSource extends AbstractMessageSource<String>
 		implements ApplicationEventPublisherAware {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final BufferedReader reader;
 
 	private final boolean blockToDetectEOF;
@@ -112,7 +117,8 @@ public class CharacterStreamReadingMessageSource extends AbstractMessageSource<S
 	@Override
 	public String doReceive() {
 		try {
-			synchronized (this.reader) {
+			this.lock.lock();
+			try {
 				if (!this.blockToDetectEOF && !this.reader.ready()) {
 					return null;
 				}
@@ -122,6 +128,9 @@ public class CharacterStreamReadingMessageSource extends AbstractMessageSource<S
 				}
 				return line;
 			}
+			finally {
+				this.lock.unlock();
+			}
 		}
 		catch (IOException e) {
 			throw new MessagingException("IO failure occurred in adapter", e);

spring-integration-test/src/main/java/org/springframework/integration/test/mock/MockMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2019 the original author or authors.
+ * Copyright 2017-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,8 @@ package org.springframework.integration.test.mock;
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
@@ -51,11 +53,14 @@ import org.springframework.messaging.Message;
  * </pre>
  *
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 5.0
  */
 public class MockMessageHandler extends AbstractMessageProducingHandler {
 
+	private final Lock lock = new ReentrantLock();
+
 	protected final List<Function<Message<?>, ?>> messageFunctions = new LinkedList<>(); // NOSONAR final
 
 	private final CapturingMatcher<Message<?>> capturingMatcher;
@@ -110,13 +115,17 @@ public class MockMessageHandler extends AbstractMessageProducingHandler {
 
 		Function<Message<?>, ?> function = this.lastFunction;
 
-		synchronized (this) {
+		this.lock.lock();
+		try {
 			Iterator<Function<Message<?>, ?>> iterator = this.messageFunctions.iterator();
 			if (iterator.hasNext()) {
 				function = iterator.next();
 				iterator.remove();
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 
 		Object result = function.apply(message);
 

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/ClientWebSocketContainer.java

@@ -46,6 +46,7 @@ import org.springframework.web.socket.client.WebSocketClient;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
  *
  * @since 4.1
  */
@@ -183,12 +184,18 @@ public final class ClientWebSocketContainer extends IntegrationWebSocketContaine
 	}
 
 	@Override
-	public synchronized void start() {
-		if (!isRunning()) {
-			this.clientSession = null;
-			this.openConnectionException = null;
-			this.connectionLatch = new CountDownLatch(1);
-			this.connectionManager.start();
+	public void start() {
+		this.lock.lock();
+		try {
+			if (!isRunning()) {
+				this.clientSession = null;
+				this.openConnectionException = null;
+				this.connectionLatch = new CountDownLatch(1);
+				this.connectionManager.start();
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/IntegrationWebSocketContainer.java

@@ -21,6 +21,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -67,6 +69,8 @@ public abstract class IntegrationWebSocketContainer implements DisposableBean {
 
 	protected final Log logger = LogFactory.getLog(getClass()); // NOSONAR
 
+	protected final Lock lock = new ReentrantLock();
+
 	private WebSocketHandler webSocketHandler = new IntegrationWebSocketHandler();
 
 	protected final Map<String, WebSocketSession> sessions = new ConcurrentHashMap<>(); // NOSONAR

spring-integration-websocket/src/main/java/org/springframework/integration/websocket/ServerWebSocketContainer.java

@@ -47,6 +47,7 @@ import org.springframework.web.socket.sockjs.transport.TransportHandler;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
  *
  * @since 4.1
  */
@@ -224,9 +225,15 @@ public class ServerWebSocketContainer extends IntegrationWebSocketContainer
 	}
 
 	@Override
-	public synchronized void start() {
-		if (this.handshakeHandler instanceof Lifecycle && !isRunning()) {
-			((Lifecycle) this.handshakeHandler).start();
+	public void start() {
+		this.lock.lock();
+		try {
+			if (this.handshakeHandler instanceof Lifecycle && !isRunning()) {
+				((Lifecycle) this.handshakeHandler).start();
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 

spring-integration-ws/src/main/java/org/springframework/integration/ws/AbstractWebServiceOutboundGateway.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,8 @@ import java.io.IOException;
 import java.net.URI;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.xml.transform.TransformerException;
 
@@ -55,9 +57,12 @@ import org.springframework.xml.transform.TransformerObjectSupport;
  * @author Oleg Zhurakousky
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public abstract class AbstractWebServiceOutboundGateway extends AbstractReplyProducingMessageHandler {
 
+	private final Lock lock = new ReentrantLock();
+
 	protected final DefaultUriBuilderFactory uriFactory = new DefaultUriBuilderFactory(); // NOSONAR - final
 
 	private final String uri;
@@ -108,10 +113,14 @@ public abstract class AbstractWebServiceOutboundGateway extends AbstractReplyPro
 	 * @param uriVariableExpressions The URI variable expressions.
 	 */
 	public void setUriVariableExpressions(Map<String, Expression> uriVariableExpressions) {
-		synchronized (this.uriVariableExpressions) {
+		this.lock.lock();
+		try {
 			this.uriVariableExpressions.clear();
 			this.uriVariableExpressions.putAll(uriVariableExpressions);
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	/**

spring-integration-xml/src/main/java/org/springframework/integration/xml/DefaultXmlPayloadConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,8 @@ import java.io.ByteArrayInputStream;
 import java.io.File;
 import java.io.InputStream;
 import java.io.StringReader;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
@@ -43,11 +45,13 @@ import org.springframework.xml.DocumentBuilderFactoryUtils;
  *
  * @author Jonas Partner
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class DefaultXmlPayloadConverter implements XmlPayloadConverter {
 
 	private final DocumentBuilderFactory documentBuilderFactory;
 
+	private final Lock lock = new ReentrantLock();
 
 	public DefaultXmlPayloadConverter() {
 		this(DocumentBuilderFactoryUtils.newInstance());
@@ -142,13 +146,17 @@ public class DefaultXmlPayloadConverter implements XmlPayloadConverter {
 		}
 	}
 
-	protected synchronized DocumentBuilder getDocumentBuilder() {
+	protected DocumentBuilder getDocumentBuilder() {
+		this.lock.lock();
 		try {
 			return this.documentBuilderFactory.newDocumentBuilder();
 		}
 		catch (ParserConfigurationException e) {
 			throw new MessagingException("failed to create a new DocumentBuilder", e);
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 }

spring-integration-xml/src/main/java/org/springframework/integration/xml/result/DomResultFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,9 @@
 
 package org.springframework.integration.xml.result;
 
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;
@@ -30,11 +33,16 @@ import org.springframework.xml.DocumentBuilderFactoryUtils;
  * @author Jonas Partner
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
  */
 public class DomResultFactory implements ResultFactory {
 
 	private final DocumentBuilderFactory documentBuilderFactory;
 
+	private final Lock documentBuilderFactoryMonitor = new ReentrantLock();
+
+	private final Lock lock = new ReentrantLock();
+
 
 	public DomResultFactory() {
 		this(DocumentBuilderFactoryUtils.newInstance());
@@ -48,7 +56,8 @@ public class DomResultFactory implements ResultFactory {
 
 
 	@Override
-	public synchronized Result createResult(Object payload) {
+	public Result createResult(Object payload) {
+		this.lock.lock();
 		try {
 			return new DOMResult(getNewDocumentBuilder().newDocument());
 		}
@@ -56,12 +65,19 @@ public class DomResultFactory implements ResultFactory {
 			throw new MessagingException("failed to create Result for payload type [" +
 					payload.getClass().getName() + "]", e);
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	protected DocumentBuilder getNewDocumentBuilder() throws ParserConfigurationException {
-		synchronized (this.documentBuilderFactory) {
+		this.documentBuilderFactoryMonitor.lock();
+		try {
 			return this.documentBuilderFactory.newDocumentBuilder();
 		}
+		finally {
+			this.documentBuilderFactoryMonitor.unlock();
+		}
 	}
 
 }

spring-integration-xml/src/main/java/org/springframework/integration/xml/source/DomSourceFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@ package org.springframework.integration.xml.source;
 
 import java.io.File;
 import java.io.StringReader;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
@@ -39,9 +41,12 @@ import org.springframework.xml.DocumentBuilderFactoryUtils;
  * @author Jonas Partner
  * @author Mark Fisher
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class DomSourceFactory implements SourceFactory {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final DocumentBuilderFactory documentBuilderFactory;
 
 
@@ -99,9 +104,13 @@ public class DomSourceFactory implements SourceFactory {
 	}
 
 	private DocumentBuilder getNewDocumentBuilder() throws ParserConfigurationException {
-		synchronized (this.documentBuilderFactory) {
+		this.lock.lock();
+		try {
 			return this.documentBuilderFactory.newDocumentBuilder();
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 }

spring-integration-xml/src/main/java/org/springframework/integration/xml/source/StringSourceFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@ package org.springframework.integration.xml.source;
 
 import java.io.File;
 import java.io.FileReader;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.xml.transform.Source;
 import javax.xml.transform.Transformer;
@@ -40,9 +42,12 @@ import org.springframework.xml.transform.TransformerFactoryUtils;
  * @author Jonas Partner
  * @author Mark Fisher
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class StringSourceFactory implements SourceFactory {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final TransformerFactory transformerFactory;
 
 
@@ -96,13 +101,17 @@ public class StringSourceFactory implements SourceFactory {
 		}
 	}
 
-	private synchronized Transformer getTransformer() {
+	private Transformer getTransformer() {
+		this.lock.lock();
 		try {
 			return this.transformerFactory.newTransformer();
 		}
 		catch (Exception e) {
 			throw new MessagingException("Exception creating transformer", e);
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 }

spring-integration-xml/src/main/java/org/springframework/integration/xml/splitter/XPathMessageSplitter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,8 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Function;
 
 import javax.xml.parsers.DocumentBuilder;
@@ -67,12 +69,15 @@ import org.springframework.xml.xpath.XPathExpressionFactory;
  * @author Mark Fisher
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Christian Tzolov
  */
 public class XPathMessageSplitter extends AbstractMessageSplitter {
 
 	private final TransformerFactory transformerFactory;
 
-	private final Object documentBuilderFactoryMonitor = new Object();
+	private final Lock documentBuilderFactoryMonitor = new ReentrantLock();
+
+	private final Lock transformerFactoryMonitor = new ReentrantLock();
 
 	private final XPathExpression xpathExpression;
 
@@ -249,9 +254,13 @@ public class XPathMessageSplitter extends AbstractMessageSplitter {
 	private Object splitDocument(Document document) throws ParserConfigurationException, TransformerException {
 		Object nodes = splitNode(document);
 		final Transformer transformer;
-		synchronized (this.transformerFactory) {
+		this.transformerFactoryMonitor.lock();
+		try {
 			transformer = this.transformerFactory.newTransformer();
 		}
+		finally {
+			this.transformerFactoryMonitor.unlock();
+		}
 		if (this.outputProperties != null) {
 			transformer.setOutputProperties(this.outputProperties);
 		}
@@ -317,9 +326,13 @@ public class XPathMessageSplitter extends AbstractMessageSplitter {
 	}
 
 	private DocumentBuilder getNewDocumentBuilder() throws ParserConfigurationException {
-		synchronized (this.documentBuilderFactoryMonitor) {
+		this.documentBuilderFactoryMonitor.lock();
+		try {
 			return this.documentBuilderFactory.newDocumentBuilder();
 		}
+		finally {
+			this.documentBuilderFactoryMonitor.unlock();
+		}
 	}
 
 	private final class NodeListIterator implements Iterator<Node> {

spring-integration-xml/src/main/java/org/springframework/integration/xml/transformer/ResultToDocumentTransformer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,8 @@
 package org.springframework.integration.xml.transformer;
 
 import java.io.StringReader;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
@@ -38,9 +40,12 @@ import org.springframework.xml.transform.StringResult;
  *
  * @author Jonas Partner
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class ResultToDocumentTransformer implements ResultTransformer {
 
+	private final Lock lock = new ReentrantLock();
+
 	// Not guaranteed to be thread safe
 	private final DocumentBuilderFactory documentBuilderFactory;
 
@@ -84,13 +89,17 @@ public class ResultToDocumentTransformer implements ResultTransformer {
 		}
 	}
 
-	private synchronized DocumentBuilder getDocumentBuilder() {
+	private DocumentBuilder getDocumentBuilder() {
+		this.lock.lock();
 		try {
 			return this.documentBuilderFactory.newDocumentBuilder();
 		}
 		catch (ParserConfigurationException e) {
 			throw new MessagingException("failed to create a new DocumentBuilder", e);
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 }

spring-integration-xml/src/main/java/org/springframework/integration/xml/transformer/ResultToStringTransformer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,8 @@
 package org.springframework.integration.xml.transformer;
 
 import java.util.Properties;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.xml.transform.Result;
 import javax.xml.transform.Transformer;
@@ -38,9 +40,12 @@ import org.springframework.xml.transform.TransformerFactoryUtils;
  * @author Jonas Partner
  * @author Mark Fisher
  * @author Artem Bilan
+ * @author Christian Tzolov
  */
 public class ResultToStringTransformer implements ResultTransformer {
 
+	private final Lock lock = new ReentrantLock();
+
 	private final TransformerFactory transformerFactory;
 
 	private Properties outputProperties;
@@ -90,9 +95,13 @@ public class ResultToStringTransformer implements ResultTransformer {
 
 	private Transformer getNewTransformer() throws TransformerConfigurationException {
 		Transformer transformer;
-		synchronized (this.transformerFactory) {
+		this.lock.lock();
+		try {
 			transformer = this.transformerFactory.newTransformer();
 		}
+		finally {
+			this.lock.unlock();
+		}
 		if (this.outputProperties != null) {
 			transformer.setOutputProperties(this.outputProperties);
 		}

spring-integration-xmpp/src/main/java/org/springframework/integration/xmpp/config/XmppConnectionFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,9 @@
 
 package org.springframework.integration.xmpp.config;
 
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
 import org.jivesoftware.smack.ConnectionListener;
 import org.jivesoftware.smack.XMPPConnection;
 import org.jivesoftware.smack.roster.Roster;
@@ -40,6 +43,7 @@ import org.springframework.util.StringUtils;
  * @author Artem Bilan
  * @author Philipp Etschel
  * @author Gary Russell
+ * @author Christian Tzolov
  *
  * @since 2.0
  *
@@ -47,7 +51,7 @@ import org.springframework.util.StringUtils;
  */
 public class XmppConnectionFactoryBean extends AbstractFactoryBean<XMPPConnection> implements SmartLifecycle {
 
-	private final Object lifecycleMonitor = new Object();
+	private final Lock lifecycleMonitor = new ReentrantLock();
 
 	private XMPPTCPConnectionConfiguration connectionConfiguration;
 
@@ -172,7 +176,8 @@ public class XmppConnectionFactoryBean extends AbstractFactoryBean<XMPPConnectio
 
 	@Override
 	public void start() {
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (this.running) {
 				return;
 			}
@@ -195,16 +200,23 @@ public class XmppConnectionFactoryBean extends AbstractFactoryBean<XMPPConnectio
 						+ connection.getXMPPServiceDomain(), e);
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 	}
 
 	@Override
 	public void stop() {
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (this.isRunning()) {
 				getConnection().disconnect();
 				this.running = false;
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 	}
 
 	@Override

spring-integration-zeromq/src/main/java/org/springframework/integration/zeromq/ZeroMqProxy.java

@@ -20,6 +20,8 @@ import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Consumer;
 
 import org.apache.commons.logging.Log;
@@ -58,6 +60,7 @@ import org.springframework.util.Assert;
  * The address for this socket is {@code "inproc://" + beanName + ".capture"}.
  *
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 5.4
  *
@@ -67,6 +70,8 @@ public class ZeroMqProxy implements InitializingBean, SmartLifecycle, BeanNameAw
 
 	private static final Log LOG = LogFactory.getLog(ZeroMqProxy.class);
 
+	private final Lock lock = new ReentrantLock();
+
 	private final ZContext context;
 
 	private final Type type;
@@ -247,65 +252,78 @@ public class ZeroMqProxy implements InitializingBean, SmartLifecycle, BeanNameAw
 	}
 
 	@Override
-	public synchronized void start() {
-		if (!this.running.get()) {
-			this.proxyExecutor
-					.execute(() -> {
-						ZMQ.Socket captureSocket = null;
-						if (this.exposeCaptureSocket) {
-							captureSocket = this.context.createSocket(SocketType.PUB);
-						}
-						try (
-								ZMQ.Socket frontendSocket = this.context.createSocket(this.type.getFrontendSocketType());
-								ZMQ.Socket backendSocket = this.context.createSocket(this.type.getBackendSocketType());
-								ZMQ.Socket controlSocket = this.context.createSocket(SocketType.PAIR)
-						) {
-
-							if (this.frontendSocketConfigurer != null) {
-								this.frontendSocketConfigurer.accept(frontendSocket);
+	public void start() {
+		this.lock.lock();
+		try {
+			if (!this.running.get()) {
+				this.proxyExecutor
+						.execute(() -> {
+							ZMQ.Socket captureSocket = null;
+							if (this.exposeCaptureSocket) {
+								captureSocket = this.context.createSocket(SocketType.PUB);
 							}
+							try (
+									ZMQ.Socket frontendSocket = this.context
+											.createSocket(this.type.getFrontendSocketType());
+									ZMQ.Socket backendSocket = this.context
+											.createSocket(this.type.getBackendSocketType());
+									ZMQ.Socket controlSocket = this.context.createSocket(SocketType.PAIR)) {
 
-							if (this.backendSocketConfigurer != null) {
-								this.backendSocketConfigurer.accept(backendSocket);
-							}
+								if (this.frontendSocketConfigurer != null) {
+									this.frontendSocketConfigurer.accept(frontendSocket);
+								}
 
-							this.frontendPort.set(bindSocket(frontendSocket, this.frontendPort.get())); // NOSONAR
-							this.backendPort.set(bindSocket(backendSocket, this.backendPort.get())); // NOSONAR
-							boolean bound = controlSocket.bind(this.controlAddress); // NOSONAR
-							if (!bound) {
-								throw new IllegalArgumentException("Cannot bind ZeroMQ socket to address: "
-										+ this.controlAddress);
-							}
-							if (captureSocket != null) {
-								bound = captureSocket.bind(this.captureAddress);
+								if (this.backendSocketConfigurer != null) {
+									this.backendSocketConfigurer.accept(backendSocket);
+								}
+
+								this.frontendPort.set(bindSocket(frontendSocket, this.frontendPort.get())); // NOSONAR
+								this.backendPort.set(bindSocket(backendSocket, this.backendPort.get())); // NOSONAR
+								boolean bound = controlSocket.bind(this.controlAddress); // NOSONAR
 								if (!bound) {
 									throw new IllegalArgumentException("Cannot bind ZeroMQ socket to address: "
-											+ this.captureAddress);
+											+ this.controlAddress);
+								}
+								if (captureSocket != null) {
+									bound = captureSocket.bind(this.captureAddress);
+									if (!bound) {
+										throw new IllegalArgumentException("Cannot bind ZeroMQ socket to address: "
+												+ this.captureAddress);
+									}
+								}
+								this.running.set(true);
+								ZMQ.proxy(frontendSocket, backendSocket, captureSocket, controlSocket);
+							}
+							catch (Exception ex) { // NOSONAR
+								LOG.error("Cannot start ZeroMQ proxy from bean: " + this.beanName, ex);
+							}
+							finally {
+								if (captureSocket != null) {
+									captureSocket.close();
 								}
 							}
-							this.running.set(true);
-							ZMQ.proxy(frontendSocket, backendSocket, captureSocket, controlSocket);
-						}
-						catch (Exception ex) { // NOSONAR
-							LOG.error("Cannot start ZeroMQ proxy from bean: " + this.beanName, ex);
-						}
-						finally {
-							if (captureSocket != null) {
-								captureSocket.close();
-							}
-						}
-					});
+						});
+			}
+		}
+		finally {
+			this.lock.unlock();
 		}
 	}
 
 	@Override
-	public synchronized void stop() {
-		if (this.running.getAndSet(false)) {
-			try (ZMQ.Socket commandSocket = this.context.createSocket(SocketType.PAIR)) {
-				commandSocket.connect(this.controlAddress); // NOSONAR
-				commandSocket.send(zmq.ZMQ.PROXY_TERMINATE);
+	public void stop() {
+		this.lock.lock();
+		try {
+			if (this.running.getAndSet(false)) {
+				try (ZMQ.Socket commandSocket = this.context.createSocket(SocketType.PAIR)) {
+					commandSocket.connect(this.controlAddress); // NOSONAR
+					commandSocket.send(zmq.ZMQ.PROXY_TERMINATE);
+				}
 			}
 		}
+		finally {
+			this.lock.unlock();
+		}
 	}
 
 	@Override

spring-integration-zookeeper/src/main/java/org/springframework/integration/zookeeper/config/CuratorFrameworkFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2019 the original author or authors.
+ * Copyright 2015-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,9 @@
 
 package org.springframework.integration.zookeeper.config;
 
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
 import org.apache.curator.RetryPolicy;
 import org.apache.curator.framework.CuratorFramework;
 import org.apache.curator.framework.CuratorFrameworkFactory;
@@ -31,12 +34,13 @@ import org.springframework.util.Assert;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 4.2
  */
 public class CuratorFrameworkFactoryBean implements FactoryBean<CuratorFramework>, SmartLifecycle {
 
-	private final Object lifecycleLock = new Object();
+	private final Lock lifecycleLock = new ReentrantLock();
 
 	private final CuratorFramework client;
 
@@ -109,7 +113,8 @@ public class CuratorFrameworkFactoryBean implements FactoryBean<CuratorFramework
 
 	@Override
 	public void start() {
-		synchronized (this.lifecycleLock) {
+		this.lifecycleLock.lock();
+		try {
 			if (!this.running) {
 				if (this.client != null) {
 					this.client.start();
@@ -117,16 +122,23 @@ public class CuratorFrameworkFactoryBean implements FactoryBean<CuratorFramework
 				this.running = true;
 			}
 		}
+		finally {
+			this.lifecycleLock.unlock();
+		}
 	}
 
 	@Override
 	public void stop() {
-		synchronized (this.lifecycleLock) {
+		this.lifecycleLock.lock();
+		try {
 			if (this.running) {
 				CloseableUtils.closeQuietly(this.client);
 				this.running = false;
 			}
 		}
+		finally {
+			this.lifecycleLock.unlock();
+		}
 	}
 
 	@Override

spring-integration-zookeeper/src/main/java/org/springframework/integration/zookeeper/config/LeaderInitiatorFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2020 the original author or authors.
+ * Copyright 2015-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,6 +37,7 @@ import org.springframework.util.Assert;
  *
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Christian Tzolov
  *
  * @since 4.2
  */
@@ -177,7 +178,7 @@ public class LeaderInitiatorFactoryBean
 	}
 
 	@Override
-	public synchronized LeaderInitiator getObject() {
+	public LeaderInitiator getObject() {
 		return this.leaderInitiator;
 	}
 

spring-integration-zookeeper/src/main/java/org/springframework/integration/zookeeper/leader/LeaderInitiator.java

@@ -18,6 +18,8 @@ package org.springframework.integration.zookeeper.leader;
 
 import java.util.Collection;
 import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -43,6 +45,7 @@ import org.springframework.util.StringUtils;
  * @author Gary Russell
  * @author Artem Bilan
  * @author Ivan Zaitsev
+ * @author Christian Tzolov
  *
  * @since 4.2
  */
@@ -66,7 +69,7 @@ public class LeaderInitiator implements SmartLifecycle {
 	 */
 	private final Candidate candidate;
 
-	private final Object lifecycleMonitor = new Object();
+	private final Lock lifecycleMonitor = new ReentrantLock();
 
 	/**
 	 * Base path in a zookeeper
@@ -159,7 +162,8 @@ public class LeaderInitiator implements SmartLifecycle {
 	 */
 	@Override
 	public void start() {
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (!this.running) {
 				if (this.client.getState() != CuratorFrameworkState.STARTED) {
 					// we want to do curator start here because it needs to
@@ -177,6 +181,9 @@ public class LeaderInitiator implements SmartLifecycle {
 				LOGGER.debug("Started LeaderInitiator");
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 	}
 
 	/**
@@ -185,13 +192,17 @@ public class LeaderInitiator implements SmartLifecycle {
 	 */
 	@Override
 	public void stop() {
-		synchronized (this.lifecycleMonitor) {
+		this.lifecycleMonitor.lock();
+		try {
 			if (this.running) {
 				this.leaderSelector.close();
 				this.running = false;
 				LOGGER.debug("Stopped LeaderInitiator");
 			}
 		}
+		finally {
+			this.lifecycleMonitor.unlock();
+		}
 	}
 
 	/**

spring-integration-zookeeper/src/main/java/org/springframework/integration/zookeeper/lock/ZookeeperLockRegistry.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2021 the original author or authors.
+ * Copyright 2015-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,7 @@ import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.curator.framework.CuratorFramework;
 import org.apache.curator.framework.recipes.locks.InterProcessMutex;
@@ -44,6 +45,7 @@ import org.springframework.util.Assert;
  * @author Artem Bilan
  * @author Vedran Pavic
  * @author Unseok Kim
+ * @author Christian Tzolov
  *
  * @since 4.2
  *
@@ -58,6 +60,8 @@ public class ZookeeperLockRegistry implements ExpirableLockRegistry, DisposableB
 
 	private static final int DEFAULT_CAPACITY = 30_000;
 
+	private final Lock locksLock = new ReentrantLock();
+
 	private final Map<String, ZkLock> locks =
 			new LinkedHashMap<String, ZkLock>(16, 0.75F, true) {
 
@@ -145,9 +149,13 @@ public class ZookeeperLockRegistry implements ExpirableLockRegistry, DisposableB
 		Assert.isInstanceOf(String.class, lockKey);
 		String path = this.keyToPath.pathFor((String) lockKey);
 		ZkLock lock;
-		synchronized (this.locks) {
+		this.locksLock.lock();
+		try {
 			lock = this.locks.computeIfAbsent(path, p -> new ZkLock(this.client, this.mutexTaskExecutor, p));
 		}
+		finally {
+			this.locksLock.unlock();
+		}
 		if (this.trackingTime) {
 			lock.setLastUsed(System.currentTimeMillis());
 		}
@@ -155,10 +163,9 @@ public class ZookeeperLockRegistry implements ExpirableLockRegistry, DisposableB
 	}
 
 	/**
-	 * Remove locks last acquired more than 'age' ago that are not currently locked.
-	 * Expiry is not supported if the {@link KeyToPathStrategy} is bounded (returns a finite
-	 * number of paths). With such a {@link KeyToPathStrategy}, the overhead of tracking when
-	 * a lock is obtained is avoided.
+	 * Remove locks last acquired more than 'age' ago that are not currently locked. Expiry is not supported if the
+	 * {@link KeyToPathStrategy} is bounded (returns a finite number of paths). With such a {@link KeyToPathStrategy},
+	 * the overhead of tracking when a lock is obtained is avoided.
 	 * @param age the time since the lock was last obtained.
 	 */
 	@Override
@@ -168,13 +175,18 @@ public class ZookeeperLockRegistry implements ExpirableLockRegistry, DisposableB
 		}
 
 		long now = System.currentTimeMillis();
-		synchronized (this.locks) {
+		this.locksLock.lock();
+		try {
 			this.locks.entrySet()
 					.removeIf(entry -> {
 						ZkLock lock = entry.getValue();
 						return now - lock.getLastUsed() > age && !lock.isAcquiredInThisProcess();
 					});
 		}
+		finally {
+			this.locksLock.unlock();
+		}
+
 	}
 
 	@Override