如何获取线程池ThreadPoolExecutor正在运行的线程
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如何获取线程池ThreadPoolExecutor正在运行的线程?
这里有两种方法,如下代码:
package com.itbac.thread; import java.util.HashSet; import java.util.Set; import java.util.concurrent.*; import java.util.stream.Stream; /** * ThreadPoolExecutor 的 beforeExecute() 和 afterExecute()方法, * 不是继承自 AbstractExecutorService , 这是设计上的一个败笔。 * 例如 netty 就是去实现 AbstractExecutorService的 * * 线程池问题:如何获取线程池ThreadPoolExecutor正在运行的线程? */ public class ThreadPoolExecutorThreadQuestion { public static void main(String[] args) throws InterruptedException { //main 线程启动子线程,子线程的创造来自于 Executors.defaultThreadFactory() ExecutorService executorService = Executors.newCachedThreadPool(); //定义线程容器,通过java的引用类型记录数据。 Set<Thread> threadsContainer = new HashSet<>(); //自定义的方法 setThreadFactory(executorService, threadsContainer); for (int i = 0; i < 5; i++) { executorService.submit(() -> { }); } //线程池等待执行 3 ms executorService.awaitTermination(3, TimeUnit.MILLISECONDS); threadsContainer.stream(). //过滤调不存活 filter(Thread::isAlive). forEach(thread -> System.out.println("方法1:线程池的线程:" + thread) ); //方法二: Thread mainThread = Thread.currentThread(); ThreadGroup mainThreadThreadGroup = mainThread.getThreadGroup(); //获取线程组中的线程。 int count = mainThreadThreadGroup.activeCount(); System.out.println("count:"+count); Thread[] threads = new Thread[count]; //enumerate 枚举,recurse 递归 mainThreadThreadGroup.enumerate(threads, true); Stream.of(threads).filter(Thread::isAlive).forEach(thread -> System.out.println("方法2:线程池的线程:" + thread )); //关闭线程池 executorService.shutdown(); /** * 输出结果: 方法1:线程池的线程:Thread[pool-1-thread-3,5,main] 方法1:线程池的线程:Thread[pool-1-thread-1,5,main] 方法1:线程池的线程:Thread[pool-1-thread-4,5,main] 方法1:线程池的线程:Thread[pool-1-thread-5,5,main] 方法1:线程池的线程:Thread[pool-1-thread-2,5,main] count:7 方法2:线程池的线程:Thread[main,5,main] 主线程 方法2:线程池的线程:Thread[Monitor Ctrl-Break,5,main] 控制中断监视器 方法2:线程池的线程:Thread[pool-1-thread-1,5,main] 方法2:线程池的线程:Thread[pool-1-thread-2,5,main] 方法2:线程池的线程:Thread[pool-1-thread-3,5,main] 方法2:线程池的线程:Thread[pool-1-thread-4,5,main] 方法2:线程池的线程:Thread[pool-1-thread-5,5,main] */ } private static void setThreadFactory(ExecutorService executorService,Set<Thread> threadsContainer){ if (executorService instanceof ThreadPoolExecutor) { ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executorService; //获取线程工厂 ThreadFactory oldThreadFactory = threadPoolExecutor.getThreadFactory(); //在把线程工程设置到包装类 DelegatingThreadFactory ,再设置回线程池。 threadPoolExecutor.setThreadFactory(new MyThreadFactory(oldThreadFactory,threadsContainer)); } } //我的的线程工厂 private static class MyThreadFactory implements ThreadFactory { private final ThreadFactory threadFactory; private final Set<Thread> threadsContainer; private MyThreadFactory(ThreadFactory threadFactory, Set<Thread> threadsContainer) { this.threadFactory = threadFactory; this.threadsContainer = threadsContainer; } @Override public Thread newThread(Runnable r) { Thread thread = threadFactory.newThread(r); //cache thread 记录线程 threadsContainer.add(thread); //删除不存活的线程 // threadsContainer.removeIf(next -> !next.isAlive()); return thread; } } }
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