ScheduledExecutorService创建newScheduledThreadPool线程池遇到的问题

最新推荐文章于 2025-06-27 02:46:41 发布

原创最新推荐文章于 2025-06-27 02:46:41 发布 · 2.8k 阅读

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本文探讨ScheduledExecutorService创建的newScheduledThreadPool线程池在处理任务时的特性：1) 如何使用scheduledFuture捕获并处理task异常；2) task运行超时与任务调度的关系；3) 当线程池大小小于任务数时，可能出现的任务执行异常情况。通过两个实例展示了线程池为1和2时的不同表现，并分享了相关的人工智能教程。

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最近线程池老是遇到执行两次的情况，故作了分析，情况如下

package test;import java.util.Date;import java.util.concurrent.ExecutionException;import java.util.concurrent.Executors;import java.util.concurrent.ScheduledExecutorService;import java.util.concurrent.ScheduledFuture;import java.util.concurrent.TimeUnit;public class Test { static class EchoServer1 implements Runnable {  @Override  public void run() {   // TODO Auto-generated method stub   try {    Thread.sleep(10000);    i++;   } catch (InterruptedException e) {    // TODO Auto-generated catch block    e.printStackTrace();   }   if(i==3){    throw new java.lang.RuntimeException("Dasds");   }   System.out.println(i+"-"+10+"-"+Thread.currentThread().getName() +"-"+new Date());  }   } static int i =0; static class EchoServer2 implements Runnable {  @Override  public void run() {   // TODO Auto-generated method stub      System.out.println(20+"-"+Thread.currentThread().getName() +"-"+new Date());  }   }  public static void main(String[] args){  ScheduledExecutorService executor = Executors.newScheduledThreadPool(2);    executor.scheduleAtFixedRate(               new EchoServer2(),               0,               10,               TimeUnit.SECONDS);    ScheduledFuture<?> future = executor.scheduleAtFixedRate(                new EchoServer1(),                0,                5,                TimeUnit.SECONDS);    try {        try {     future.get();         } catch (InterruptedException e) {     // TODO Auto-generated catch block     e.printStackTrace();    }    } catch (ExecutionException e) {        Throwable cause = e.getCause();        cause.printStackTrace();        future.cancel(false);    } }}

1、可用scheduledFuture 捕获 task异常，并停止某个task，不影响其余task的运行。

2、若task运行时间大于间隔时间，则下一次task将在上一次task后马上运行，不会产生同时2个相同task的运行情况发生。

3、若线程池大小小于task大小，则若在情况2下，有另一条task占据了现有线程池（即阻塞了原task的一次运行），

则会造成原task在另一条task结束后，执行两次。

线程池为1：

20-pool-1-thread-1-Mon Dec 29 21:34:08 CST 2014
1-10-pool-1-thread-1-Mon Dec 29 21:34:18 CST 2014
2-10-pool-1-thread-1-Mon Dec 29 21:34:28 CST 2014
20-pool-1-thread-1-Mon Dec 29 21:34:28 CST 2014
20-pool-1-thread-1-Mon Dec 29 21:34:38 CST 2014
20-pool-1-thread-1-Mon Dec 29 21:34:38 CST 2014
java.lang.RuntimeException: Dasds
at test.Test$EchoServer1.run(Test.java:23)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask$Sync.innerRunAndReset(Unknown Source)
at java.util.concurrent.FutureTask.runAndReset(Unknown Source)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(Unknown Source)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(Unknown Source)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
20-pool-1-thread-1-Mon Dec 29 21:34:48 CST 2014

线程池为2：

20-pool-1-thread-1-Mon Dec 29 21:33:13 CST 2014
20-pool-1-thread-1-Mon Dec 29 21:33:23 CST 2014
1-10-pool-1-thread-2-Mon Dec 29 21:33:23 CST 2014
20-pool-1-thread-1-Mon Dec 29 21:33:33 CST 2014
2-10-pool-1-thread-2-Mon Dec 29 21:33:33 CST 2014
20-pool-1-thread-1-Mon Dec 29 21:33:43 CST 2014
java.lang.RuntimeException: Dasds
at test.Test$EchoServer1.run(Test.java:23)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask$Sync.innerRunAndReset(Unknown Source)
at java.util.concurrent.FutureTask.runAndReset(Unknown Source)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(Unknown Source)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(Unknown Source)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
20-pool-1-thread-2-Mon Dec 29 21:33:53 CST 2014