Support for JDK 8's "common" ForkJoinPool

Issue: SPR-9644

spring-context/src/main/java/org/springframework/scheduling/concurrent/ForkJoinPoolFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 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 +17,7 @@
 package org.springframework.scheduling.concurrent;
 
 import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.TimeUnit;
 
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.FactoryBean;
@@ -24,7 +25,7 @@ import org.springframework.beans.factory.InitializingBean;
 
 /**
  * A Spring {@link FactoryBean} that builds and exposes a preconfigured {@link ForkJoinPool}.
- * May be used on Java 7 as well as on Java 6 with {@code jsr166.jar} on the classpath
+ * May be used on Java 7 and 8 as well as on Java 6 with {@code jsr166.jar} on the classpath
  * (ideally on the VM bootstrap classpath).
  *
  * <p>For details on the ForkJoinPool API and its use with RecursiveActions, see the
@@ -38,6 +39,8 @@ import org.springframework.beans.factory.InitializingBean;
  */
 public class ForkJoinPoolFactoryBean implements FactoryBean<ForkJoinPool>, InitializingBean, DisposableBean {
 
+	private boolean commonPool = false;
+
 	private int parallelism = Runtime.getRuntime().availableProcessors();
 
 	private ForkJoinPool.ForkJoinWorkerThreadFactory threadFactory = ForkJoinPool.defaultForkJoinWorkerThreadFactory;
@@ -46,9 +49,28 @@ public class ForkJoinPoolFactoryBean implements FactoryBean<ForkJoinPool>, Initi
 
 	private boolean asyncMode = false;
 
+	private int awaitTerminationSeconds = 0;
+
 	private ForkJoinPool forkJoinPool;
 
 
+	/**
+	 * Set whether to expose JDK 8's 'common' {@link ForkJoinPool}.
+	 * <p>Default is "false", creating a local {@link ForkJoinPool} instance based on the
+	 * {@link #setParallelism "parallelism"}, {@link #setThreadFactory "threadFactory"},
+	 * {@link #setUncaughtExceptionHandler "uncaughtExceptionHandler"} and
+	 * {@link #setAsyncMode "asyncMode"} properties on this FactoryBean.
+	 * <p><b>NOTE:</b> Setting this flag to "true" effectively ignores all other
+	 * properties on this FactoryBean, reusing the shared common JDK {@link ForkJoinPool}
+	 * instead. This is a fine choice on JDK 8 but does remove the application's ability
+	 * to customize ForkJoinPool behavior, in particular the use of custom threads.
+	 * @since 3.2
+	 * @see java.util.concurrent.ForkJoinPool#commonPool()
+	 */
+	public void setCommonPool(boolean commonPool) {
+		this.commonPool = commonPool;
+	}
+
 	/**
 	 * Specify the parallelism level. Default is {@link Runtime#availableProcessors()}.
 	 */
@@ -82,9 +104,30 @@ public class ForkJoinPoolFactoryBean implements FactoryBean<ForkJoinPool>, Initi
 		this.asyncMode = asyncMode;
 	}
 
+	/**
+	 * Set the maximum number of seconds that this ForkJoinPool is supposed to block
+	 * on shutdown in order to wait for remaining tasks to complete their execution
+	 * before the rest of the container continues to shut down. This is particularly
+	 * useful if your remaining tasks are likely to need access to other resources
+	 * that are also managed by the container.
+	 * <p>By default, this ForkJoinPool won't wait for the termination of tasks at all.
+	 * It will continue to fully execute all ongoing tasks as well as all remaining
+	 * tasks in the queue, in parallel to the rest of the container shutting down.
+	 * In contrast, if you specify an await-termination period using this property,
+	 * this executor will wait for the given time (max) for the termination of tasks.
+	 * <p>Note that this feature works for the {@link #setCommonPool "commonPool"}
+	 * mode as well. The underlying ForkJoinPool won't actually terminate in that
+	 * case but will wait for all tasks to terminate.
+	 * @see java.util.concurrent.ForkJoinPool#shutdown()
+	 * @see java.util.concurrent.ForkJoinPool#awaitTermination
+	 */
+	public void setAwaitTerminationSeconds(int awaitTerminationSeconds) {
+		this.awaitTerminationSeconds = awaitTerminationSeconds;
+	}
+
 	public void afterPropertiesSet() {
-		this.forkJoinPool =
-				new ForkJoinPool(this.parallelism, this.threadFactory, this.uncaughtExceptionHandler, this.asyncMode);
+		this.forkJoinPool = (this.commonPool ? ForkJoinPool.commonPool() :
+				new ForkJoinPool(this.parallelism, this.threadFactory, this.uncaughtExceptionHandler, this.asyncMode));
 	}
 
 
@@ -102,7 +145,18 @@ public class ForkJoinPoolFactoryBean implements FactoryBean<ForkJoinPool>, Initi
 
 
 	public void destroy() {
+		// Ignored for the common pool.
 		this.forkJoinPool.shutdown();
+
+		// Wait for all tasks to terminate - works for the common pool as well.
+		if (this.awaitTerminationSeconds > 0) {
+			try {
+				this.forkJoinPool.awaitTermination(this.awaitTerminationSeconds, TimeUnit.SECONDS);
+			}
+			catch (InterruptedException ex) {
+				Thread.currentThread().interrupt();
+			}
+		}
 	}
 
 }