Introduce @BatchTaskExecutor for customizing Batch's task executor

Closes gh-40040

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/batch/BatchAutoConfiguration.java

@@ -44,6 +44,7 @@ import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.core.convert.support.ConfigurableConversionService;
+import org.springframework.core.task.TaskExecutor;
 import org.springframework.jdbc.datasource.init.DatabasePopulator;
 import org.springframework.transaction.PlatformTransactionManager;
 import org.springframework.transaction.annotation.Isolation;
@@ -101,6 +102,8 @@ public class BatchAutoConfiguration {
 
 		private final PlatformTransactionManager transactionManager;
 
+		private final TaskExecutor taskExector;
+
 		private final BatchProperties properties;
 
 		private final List<BatchConversionServiceCustomizer> batchConversionServiceCustomizers;
@@ -110,11 +113,12 @@ public class BatchAutoConfiguration {
 		SpringBootBatchConfiguration(DataSource dataSource, @BatchDataSource ObjectProvider<DataSource> batchDataSource,
 				PlatformTransactionManager transactionManager,
 				@BatchTransactionManager ObjectProvider<PlatformTransactionManager> batchTransactionManager,
-				BatchProperties properties,
+				@BatchTaskExecutor ObjectProvider<TaskExecutor> batchTaskExecutor, BatchProperties properties,
 				ObjectProvider<BatchConversionServiceCustomizer> batchConversionServiceCustomizers,
 				ObjectProvider<ExecutionContextSerializer> executionContextSerializer) {
 			this.dataSource = batchDataSource.getIfAvailable(() -> dataSource);
 			this.transactionManager = batchTransactionManager.getIfAvailable(() -> transactionManager);
+			this.taskExector = batchTaskExecutor.getIfAvailable();
 			this.properties = properties;
 			this.batchConversionServiceCustomizers = batchConversionServiceCustomizers.orderedStream().toList();
 			this.executionContextSerializer = executionContextSerializer.getIfAvailable();
@@ -157,6 +161,11 @@ public class BatchAutoConfiguration {
 					: super.getExecutionContextSerializer();
 		}
 
+		@Override
+		protected TaskExecutor getTaskExecutor() {
+			return (this.taskExector != null) ? this.taskExector : super.getTaskExecutor();
+		}
+
 	}
 
 	@Configuration(proxyBeanMethods = false)

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/batch/BatchTaskExecutor.java

@@ -0,0 +1,43 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.batch;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.context.annotation.Primary;
+import org.springframework.core.task.TaskExecutor;
+
+/**
+ * Qualifier annotation for a {@link TaskExecutor} to be injected into Batch
+ * auto-configuration. Can be used on a secondary task executor source, if there is
+ * another one marked as {@link Primary @Primary}.
+ *
+ * @author Andy Wilkinson
+ * @since 3.4.0
+ */
+@Target({ ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.TYPE, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Qualifier
+public @interface BatchTaskExecutor {
+
+}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/batch/BatchAutoConfigurationTests.java

@@ -78,6 +78,10 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
 import org.springframework.core.annotation.Order;
 import org.springframework.core.convert.support.ConfigurableConversionService;
+import org.springframework.core.task.AsyncTaskExecutor;
+import org.springframework.core.task.SimpleAsyncTaskExecutor;
+import org.springframework.core.task.SyncTaskExecutor;
+import org.springframework.core.task.TaskExecutor;
 import org.springframework.jdbc.BadSqlGrammarException;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.jdbc.datasource.DataSourceTransactionManager;
@@ -361,6 +365,22 @@ class BatchAutoConfigurationTests {
 			});
 	}
 
+	@Test
+	void testBatchTaskExecutor() {
+		this.contextRunner
+			.withUserConfiguration(TestConfiguration.class, BatchTaskExecutorConfiguration.class,
+					EmbeddedDataSourceConfiguration.class)
+			.run((context) -> {
+				assertThat(context).hasSingleBean(SpringBootBatchConfiguration.class).hasBean("batchTaskExecutor");
+				TaskExecutor batchTaskExecutor = context.getBean("batchTaskExecutor", TaskExecutor.class);
+				assertThat(batchTaskExecutor).isInstanceOf(AsyncTaskExecutor.class);
+				assertThat(context.getBean(SpringBootBatchConfiguration.class).getTaskExecutor())
+					.isEqualTo(batchTaskExecutor);
+				assertThat(context.getBean(JobLauncher.class)).hasFieldOrPropertyWithValue("taskExecutor",
+						batchTaskExecutor);
+			});
+	}
+
 	@Test
 	void jobRepositoryBeansDependOnBatchDataSourceInitializer() {
 		this.contextRunner.withUserConfiguration(TestConfiguration.class, EmbeddedDataSourceConfiguration.class)
@@ -551,6 +571,23 @@ class BatchAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class BatchTaskExecutorConfiguration {
+
+		@Bean
+		@Primary
+		TaskExecutor taskExecutor() {
+			return new SyncTaskExecutor();
+		}
+
+		@Bean
+		@BatchTaskExecutor
+		TaskExecutor batchTaskExecutor() {
+			return new SimpleAsyncTaskExecutor();
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class EmptyConfiguration {
 

spring-boot-project/spring-boot-docs/src/docs/antora/modules/how-to/pages/batch.adoc

@@ -29,6 +29,14 @@ If you do so and want two transaction managers, remember to mark the other one a
 
 
 
+[[howto.batch.specifying-a-task-executor]]
+== Specifying a Batch Task Executor
+
+Similar to xref:batch.adoc#howto.batch.specifying-a-data-source[], you can define a `TaskExecutor` for use in the batch processing by marking it as `@BatchTaskExecutor`.
+If you do so and want two task executors, remember to mark the other one as `@Primary`.
+
+
+
 [[howto.batch.running-jobs-on-startup]]
 == Running Spring Batch Jobs on Startup