如何停止的ScheduledThreadPoolExecutor任务一次，我认为这是完成(How t

我有我安排的任务以固定速度运行的ScheduledThreadPoolExecutor。 我希望任务与最大的指定延迟运行比如说10次，直到它“成功”。 在那之后，我不会希望任务重试。 所以基本上我需要停止运行的计划的任务时，我希望它停止，但没有关闭的ScheduledThreadPoolExecutor。 任何想法，我怎么会做呢？

下面是一些伪代码 -

public class ScheduledThreadPoolExecutorTest
{
  public static ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(15);  // no multiple instances, just one to serve all requests

  class MyTask implements Runnable
  {
    private int MAX_ATTEMPTS = 10;
    public void run()
    {
      if(++attempt <= MAX_ATTEMPTS)
      {
        doX();
        if(doXSucceeded)
        {
          //stop retrying the task anymore
        }
      }
      else
      { 
        //couldn't succeed in MAX attempts, don't bother retrying anymore!
      }
    }
  }

  public void main(String[] args)
  {
    executor.scheduleAtFixedRate(new ScheduledThreadPoolExecutorTest().new MyTask(), 0, 5, TimeUnit.SECONDS);
  }
}

Answer 1:

运行该测试，将打印1 2 3 4 5和止挡

public class ScheduledThreadPoolExecutorTest {
    static ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(15); // no
    static ScheduledFuture<?> t;

    static class MyTask implements Runnable {
        private int attempt = 1;

        public void run() {
            System.out.print(attempt + " ");
            if (++attempt > 5) {
                t.cancel(false);
            }
        }
    }

    public static void main(String[] args) {
        t = executor.scheduleAtFixedRate(new MyTask(), 0, 1, TimeUnit.SECONDS);
    }
}

Answer 2:

奈斯利取消线程之外：

public class ScheduleTest {

    @Test
    public void testCancel() throws Exception {
        final ScheduledThreadPoolExecutor EXECUTOR = (ScheduledThreadPoolExecutor) Executors.newScheduledThreadPool(2);
        ScheduledFuture f1 = EXECUTOR.scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                System.out.println("Im alive 1");
            }
        }, 0, 1, TimeUnit.SECONDS);
        ScheduledFuture f2 = EXECUTOR.scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                System.out.println("Im alive 2");
            }
        }, 0, 2, TimeUnit.SECONDS);

        Thread.sleep(10000);
        f1.cancel(true);
        System.out.println("f1 cancel");
        Thread.sleep(10000);
        f2.cancel(false);
        System.out.println("f2 cancel");
        Thread.sleep(10000);
    }
}

有时线程不能被取消，这解决了通常通过volatile boolean isCancelled;

Answer 3:

CountDownLatch是一种替代方法。 当线程完成，调用countDown()上的闩锁。 调用线程调用latch.await()直到所有线程完成。 在这一点上调用ExecutorService.shutdownNow()这样你的主线程不会变成僵尸。

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

public class ScheduledThreadPoolExecutorTest {

  static int i = 0;

  public static void main(String[] args) throws Exception {
    final ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
    final CountDownLatch latch = new CountDownLatch(1);
    executor.scheduleAtFixedRate(() -> {
        System.out.println(++i);
        if (i > 4) {
          latch.countDown();
        }
    }, 0, 100, TimeUnit.MILLISECONDS);
    latch.await();
    executor.shutdownNow();
  }
}

文章来源: How to stop a task in ScheduledThreadPoolExecutor once I think it's completed