Add configuration property to disable long timers in Micrometer Observations

Set management.observations.long-task-timer.enabled = false to disable
the LongTaskTimer creation.

Closes gh-39618

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/observation/ObservationAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.List;
 
 import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.observation.DefaultMeterObservationHandler;
+import io.micrometer.core.instrument.observation.DefaultMeterObservationHandler.IgnoredMeters;
 import io.micrometer.core.instrument.observation.MeterObservationHandler;
 import io.micrometer.observation.GlobalObservationConvention;
 import io.micrometer.observation.Observation;
@@ -131,8 +132,10 @@ public class ObservationAutoConfiguration {
 		static class OnlyMetricsMeterObservationHandlerConfiguration {
 
 			@Bean
-			DefaultMeterObservationHandler defaultMeterObservationHandler(MeterRegistry meterRegistry) {
-				return new DefaultMeterObservationHandler(meterRegistry);
+			DefaultMeterObservationHandler defaultMeterObservationHandler(MeterRegistry meterRegistry,
+					ObservationProperties properties) {
+				return properties.getLongTaskTimer().isEnabled() ? new DefaultMeterObservationHandler(meterRegistry)
+						: new DefaultMeterObservationHandler(meterRegistry, IgnoredMeters.LONG_TASK_TIMER);
 			}
 
 		}
@@ -143,8 +146,10 @@ public class ObservationAutoConfiguration {
 
 			@Bean
 			TracingAwareMeterObservationHandler<Observation.Context> tracingAwareMeterObservationHandler(
-					MeterRegistry meterRegistry, Tracer tracer) {
-				DefaultMeterObservationHandler delegate = new DefaultMeterObservationHandler(meterRegistry);
+					MeterRegistry meterRegistry, Tracer tracer, ObservationProperties properties) {
+				DefaultMeterObservationHandler delegate = properties.getLongTaskTimer().isEnabled()
+						? new DefaultMeterObservationHandler(meterRegistry)
+						: new DefaultMeterObservationHandler(meterRegistry, IgnoredMeters.LONG_TASK_TIMER);
 				return new TracingAwareMeterObservationHandler<>(delegate, tracer);
 			}
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/observation/ObservationProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -45,6 +45,8 @@ public class ObservationProperties {
 	 */
 	private Map<String, Boolean> enable = new LinkedHashMap<>();
 
+	private final LongTaskTimer longTaskTimer = new LongTaskTimer();
+
 	public Map<String, Boolean> getEnable() {
 		return this.enable;
 	}
@@ -65,6 +67,10 @@ public class ObservationProperties {
 		this.keyValues = keyValues;
 	}
 
+	public LongTaskTimer getLongTaskTimer() {
+		return this.longTaskTimer;
+	}
+
 	public static class Http {
 
 		private final Client client = new Client();
@@ -135,4 +141,21 @@ public class ObservationProperties {
 
 	}
 
+	public static class LongTaskTimer {
+
+		/**
+		 * Whether to create a LongTaskTimer for every observation.
+		 */
+		private boolean enabled = true;
+
+		public boolean isEnabled() {
+			return this.enabled;
+		}
+
+		public void setEnabled(boolean enabled) {
+			this.enabled = enabled;
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/observation/ObservationAutoConfigurationTests.java

@@ -50,6 +50,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.core.annotation.Order;
+import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -334,6 +335,46 @@ class ObservationAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void shouldEnableLongTaskTimersByDefault() {
+		this.contextRunner.run((context) -> {
+			DefaultMeterObservationHandler handler = context.getBean(DefaultMeterObservationHandler.class);
+			assertThat(handler).hasFieldOrPropertyWithValue("shouldCreateLongTaskTimer", true);
+		});
+	}
+
+	@Test
+	void shouldDisableLongTaskTimerIfPropertyIsSet() {
+		this.contextRunner.withPropertyValues("management.observations.long-task-timer.enabled=false")
+			.run((context) -> {
+				DefaultMeterObservationHandler handler = context.getBean(DefaultMeterObservationHandler.class);
+				assertThat(handler).hasFieldOrPropertyWithValue("shouldCreateLongTaskTimer", false);
+			});
+	}
+
+	@Test
+	@SuppressWarnings("unchecked")
+	void shouldEnableLongTaskTimersForTracingByDefault() {
+		this.tracingContextRunner.run((context) -> {
+			TracingAwareMeterObservationHandler<Observation.Context> tracingHandler = context
+				.getBean(TracingAwareMeterObservationHandler.class);
+			Object delegate = ReflectionTestUtils.getField(tracingHandler, "delegate");
+			assertThat(delegate).hasFieldOrPropertyWithValue("shouldCreateLongTaskTimer", true);
+		});
+	}
+
+	@Test
+	@SuppressWarnings("unchecked")
+	void shouldDisableLongTaskTimerForTracingIfPropertyIsSet() {
+		this.tracingContextRunner.withPropertyValues("management.observations.long-task-timer.enabled=false")
+			.run((context) -> {
+				TracingAwareMeterObservationHandler<Observation.Context> tracingHandler = context
+					.getBean(TracingAwareMeterObservationHandler.class);
+				Object delegate = ReflectionTestUtils.getField(tracingHandler, "delegate");
+				assertThat(delegate).hasFieldOrPropertyWithValue("shouldCreateLongTaskTimer", false);
+			});
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class ObservationPredicates {