是否有ExecutorService的解决方案,时间限制每个提交的Callable

时间:2012-11-05 16:40:13

标签: java concurrency executorservice

以下是我的内容......我有一个任务列表,每个任务都会自己提交ExecutorService。我希望每个任务在开始执行后的时间限制为x MS。我已经看到了Time Limit on Individual Threads发布的解决方案,但这会在提交任务时开始设置时间限制。

我认为一个解决方案是对Time Limit on Individual Threads的公认解决方案的扩展。这会将Callable包装在另一个Callable中,一旦启动就将取消任务放在计划执行程序上。这将涉及以非平凡的方式将Callable映射到Future,所以我想我会发布以查看是否有人知道现有的解决方案(代码重用是一件很棒的事情,全部)。

感谢。

作为一个FYI,Time Limit on Individual Threads发布的解决方案如下。这再次取消了提交时间,而不是开始时间:

ExecutorService service = Executors.newFixedThreadPool(N);
ScheduledExecutorService canceller = Executors.newSingleThreadScheduledExecutor();

public <T> Future<T> executeTask(Callable<T> c, long timeoutMS){
   final Future<T> future = service.submit(c);
   canceller.schedule(new Callable<Void>(){
       public Void call(){
          future.cancel(true);
          return null;
       }
    }, timeoutMS, TimeUnit.MILLI_SECONDS);
   return future;
}

4 个答案:

答案 0 :(得分:2)

看看这是否适合你。

很抱歉,如果代码很乱,但它只是为了演示这个概念:将未来传回给任务,让任务启动自己的计时器 - 计时器将在任务开始时启动。

以下代码添加了10个任务,每个任务需要2秒才能执行,但超时时间为1秒。

import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

public class CancellableTaskDemo {
    public static void main(final String[] args) {
        new CancellableTaskDemo();
    }

    final ExecutorService ex = Executors.newFixedThreadPool(3);

    public CancellableTaskDemo() {
        for (int i = 0; i < 10; i++) {
            final int c = i;
            submitTask(new Callable<Object>() {
                @Override
                public Object call() throws Exception {
                    final long t = System.currentTimeMillis();
                    try {
                        Thread.sleep(2000);
                        System.out.println("Task " + c + " done in " + (System.currentTimeMillis() - t) + "ms");
                    } catch (final InterruptedException e) {
                        System.out.println("Task " + c + " aborted after " + (System.currentTimeMillis() - t) + "ms");
                    }
                    return null;
                }
            }, 1000);
        }
        ex.shutdown();
        try {
            ex.awaitTermination(100000, TimeUnit.MILLISECONDS);
        } catch (final InterruptedException e) {
            e.printStackTrace();
        }
    }

    private void submitTask(final Callable<Object> c, final int timeout) {
        final TimedFutureTask tft = new TimedFutureTask(c, timeout);
        final Future<?> ft = ex.submit(tft.getCallable());
        tft.setFuture(ft);
    }

    static class TimedFutureTask {
        final static ScheduledExecutorService canceller = Executors.newSingleThreadScheduledExecutor();
        private Timer cancelTimer;
        private Callable<Object> timedCallable;
        private Future<?> f;
        private int timeoutMS;

        public TimedFutureTask(final Callable<Object> callable, final int timeoutMS) {
            this.timeoutMS = timeoutMS;
            timedCallable = (new Callable<Object>() {

                @Override
                public Object call() throws Exception {

                    cancelTimer = new Timer();
                    cancelTimer.schedule(new TimerTask() {

                        @Override
                        public void run() {
                            f.cancel(true);

                        }
                    }, timeoutMS);

                    final Object res = callable.call();
                    cancelTimer.cancel();
                    return res;
                }

            });
        }

        public Callable<Object> getCallable() {
            return timedCallable;
        }

        public void setFuture(final Future<?> future) {
            f = future;
        }
    }

}

答案 1 :(得分:0)

我会使用ScheduleExecutorService。

final Future future = es.submit(myTask);
ses.schedule(new Runnable() {
    public void run() {
        future.cancel(true);
    }
}, timeout, timeUnit);

答案 2 :(得分:0)

你可以手动完成,但是它的代码太多了,无法完成一项简单的任务:(

public void run() {
    long start = System.nanoTime();
    long timeout = 60 * 1000;
    do {
        // Do work here
    } while (TimeUnit.MICROSECONDS.convert(System.nanoTime() - start,
            TimeUnit.MICROSECONDS)
            - start > timeout);
}

答案 3 :(得分:0)

您可以将计时器作为您提交的任务的一部分启动,因此它将在执行任务时启动。只是,在这种情况下,你不能使用future.cancel,但你可以打断线程。根据你提交的任务,优雅和及时终止可以很容易或不。