Java tutorial
/* * Copyright 2002-2017 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 * * http://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.scheduling.concurrent; import java.util.concurrent.ExecutorService; import java.util.concurrent.RejectedExecutionHandler; import java.util.concurrent.ThreadFactory; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.factory.BeanNameAware; import org.springframework.beans.factory.DisposableBean; import org.springframework.beans.factory.InitializingBean; import org.springframework.lang.Nullable; /** * Base class for classes that are setting up a * {@code java.util.concurrent.ExecutorService} * (typically a {@link java.util.concurrent.ThreadPoolExecutor}). * Defines common configuration settings and common lifecycle handling. * * @author Juergen Hoeller * @since 3.0 * @see java.util.concurrent.ExecutorService * @see java.util.concurrent.Executors * @see java.util.concurrent.ThreadPoolExecutor */ @SuppressWarnings("serial") public abstract class ExecutorConfigurationSupport extends CustomizableThreadFactory implements BeanNameAware, InitializingBean, DisposableBean { protected final Log logger = LogFactory.getLog(getClass()); private ThreadFactory threadFactory = this; private boolean threadNamePrefixSet = false; private RejectedExecutionHandler rejectedExecutionHandler = new ThreadPoolExecutor.AbortPolicy(); private boolean waitForTasksToCompleteOnShutdown = false; private int awaitTerminationSeconds = 0; @Nullable private String beanName; @Nullable private ExecutorService executor; /** * Set the ThreadFactory to use for the ExecutorService's thread pool. * Default is the underlying ExecutorService's default thread factory. * <p>In a Java EE 7 or other managed environment with JSR-236 support, * consider specifying a JNDI-located ManagedThreadFactory: by default, * to be found at "java:comp/DefaultManagedThreadFactory". * Use the "jee:jndi-lookup" namespace element in XML or the programmatic * {@link org.springframework.jndi.JndiLocatorDelegate} for convenient lookup. * Alternatively, consider using Spring's {@link DefaultManagedAwareThreadFactory} * with its fallback to local threads in case of no managed thread factory found. * @see java.util.concurrent.Executors#defaultThreadFactory() * @see javax.enterprise.concurrent.ManagedThreadFactory * @see DefaultManagedAwareThreadFactory */ public void setThreadFactory(@Nullable ThreadFactory threadFactory) { this.threadFactory = (threadFactory != null ? threadFactory : this); } @Override public void setThreadNamePrefix(@Nullable String threadNamePrefix) { super.setThreadNamePrefix(threadNamePrefix); this.threadNamePrefixSet = true; } /** * Set the RejectedExecutionHandler to use for the ExecutorService. * Default is the ExecutorService's default abort policy. * @see java.util.concurrent.ThreadPoolExecutor.AbortPolicy */ public void setRejectedExecutionHandler(@Nullable RejectedExecutionHandler rejectedExecutionHandler) { this.rejectedExecutionHandler = (rejectedExecutionHandler != null ? rejectedExecutionHandler : new ThreadPoolExecutor.AbortPolicy()); } /** * Set whether to wait for scheduled tasks to complete on shutdown, * not interrupting running tasks and executing all tasks in the queue. * <p>Default is "false", shutting down immediately through interrupting * ongoing tasks and clearing the queue. Switch this flag to "true" if you * prefer fully completed tasks at the expense of a longer shutdown phase. * <p>Note that Spring's container shutdown continues while ongoing tasks * are being completed. If you want this executor to block and wait for the * termination of tasks before the rest of the container continues to shut * down - e.g. in order to keep up other resources that your tasks may need -, * set the {@link #setAwaitTerminationSeconds "awaitTerminationSeconds"} * property instead of or in addition to this property. * @see java.util.concurrent.ExecutorService#shutdown() * @see java.util.concurrent.ExecutorService#shutdownNow() */ public void setWaitForTasksToCompleteOnShutdown(boolean waitForJobsToCompleteOnShutdown) { this.waitForTasksToCompleteOnShutdown = waitForJobsToCompleteOnShutdown; } /** * Set the maximum number of seconds that this executor 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 executor won't wait for the termination of tasks at all. * It will either shut down immediately, interrupting ongoing tasks and clearing * the remaining task queue - or, if the * {@link #setWaitForTasksToCompleteOnShutdown "waitForTasksToCompleteOnShutdown"} * flag has been set to {@code true}, 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. * <p>In either case, if you specify an await-termination period using this property, * this executor will wait for the given time (max) for the termination of tasks. * As a rule of thumb, specify a significantly higher timeout here if you set * "waitForTasksToCompleteOnShutdown" to {@code true} at the same time, * since all remaining tasks in the queue will still get executed - in contrast * to the default shutdown behavior where it's just about waiting for currently * executing tasks that aren't reacting to thread interruption. * @see java.util.concurrent.ExecutorService#shutdown() * @see java.util.concurrent.ExecutorService#awaitTermination */ public void setAwaitTerminationSeconds(int awaitTerminationSeconds) { this.awaitTerminationSeconds = awaitTerminationSeconds; } @Override public void setBeanName(String name) { this.beanName = name; } /** * Calls {@code initialize()} after the container applied all property values. * @see #initialize() */ @Override public void afterPropertiesSet() { initialize(); } /** * Set up the ExecutorService. */ public void initialize() { if (logger.isInfoEnabled()) { logger.info( "Initializing ExecutorService " + (this.beanName != null ? " '" + this.beanName + "'" : "")); } if (!this.threadNamePrefixSet && this.beanName != null) { setThreadNamePrefix(this.beanName + "-"); } this.executor = initializeExecutor(this.threadFactory, this.rejectedExecutionHandler); } /** * Create the target {@link java.util.concurrent.ExecutorService} instance. * Called by {@code afterPropertiesSet}. * @param threadFactory the ThreadFactory to use * @param rejectedExecutionHandler the RejectedExecutionHandler to use * @return a new ExecutorService instance * @see #afterPropertiesSet() */ protected abstract ExecutorService initializeExecutor(ThreadFactory threadFactory, RejectedExecutionHandler rejectedExecutionHandler); /** * Calls {@code shutdown} when the BeanFactory destroys * the task executor instance. * @see #shutdown() */ @Override public void destroy() { shutdown(); } /** * Perform a shutdown on the underlying ExecutorService. * @see java.util.concurrent.ExecutorService#shutdown() * @see java.util.concurrent.ExecutorService#shutdownNow() */ public void shutdown() { if (logger.isInfoEnabled()) { logger.info( "Shutting down ExecutorService" + (this.beanName != null ? " '" + this.beanName + "'" : "")); } if (this.executor != null) { if (this.waitForTasksToCompleteOnShutdown) { this.executor.shutdown(); } else { this.executor.shutdownNow(); } awaitTerminationIfNecessary(this.executor); } } /** * Wait for the executor to terminate, according to the value of the * {@link #setAwaitTerminationSeconds "awaitTerminationSeconds"} property. */ private void awaitTerminationIfNecessary(ExecutorService executor) { if (this.awaitTerminationSeconds > 0) { try { if (!executor.awaitTermination(this.awaitTerminationSeconds, TimeUnit.SECONDS)) { if (logger.isWarnEnabled()) { logger.warn("Timed out while waiting for executor" + (this.beanName != null ? " '" + this.beanName + "'" : "") + " to terminate"); } } } catch (InterruptedException ex) { if (logger.isWarnEnabled()) { logger.warn("Interrupted while waiting for executor" + (this.beanName != null ? " '" + this.beanName + "'" : "") + " to terminate"); } Thread.currentThread().interrupt(); } } } }