ChatGPT解决这个技术问题 Extra ChatGPT

如何使线程超时

我想运行一个线程一段固定的时间。如果在那段时间内没有完成,我想杀死它,抛出一些异常,或者以某种方式处理它。怎么做到呢?

正如我从 this thread 中得出的那样,一种方法是在线程的 run() 方法中使用 TimerTask。

有没有更好的解决方案?

编辑:添加赏金,因为我需要一个更清晰的答案。下面给出的 ExecutorService 代码不能解决我的问题。为什么我应该在执行后 sleep() (一些代码 - 我无法处理这段代码)?如果代码完成并且 sleep() 被中断,那怎么可能是超时?

需要执行的任务不在我的控制范围内。它可以是任何一段代码。问题是这段代码可能会陷入无限循环。我不希望这种情况发生。所以,我只想在一个单独的线程中运行该任务。父线程必须等到该线程完成并需要知道任务的状态(即它是否超时或发生了一些异常或是否成功)。如果任务进入无限循环,我的父线程会无限期地等待,这不是理想的情况。

编辑:添加赏金,因为我需要更明确的答案。下面给出的 ExecutorService 代码不能解决我的问题。为什么我应该在执行我的代码后 sleep() ?如果代码完成并且 sleep() 被中断,那怎么可能是超时?
那个 sleep() 只是一个代表“长时间运行的任务”的存根。只需将其替换为您的实际任务;)
...一个“长时间运行的任务”,恰好响应其线程上的 interrupt() 调用...并非所有“阻塞”调用都如此,正如我试图在我的回答中指出的那样。您尝试中止的任务的细节对应该使用的方法产生了巨大的影响。有关该任务的更多信息会有所帮助。
如果这些答案不能解决问题,那么我想更多的细节/代码应该有助于回答。
您想要限制时间的这些线程;他们是在进行阻塞调用,还是在某个循环中,您可以轻松地检查某个变量以查看是否该退出?

B
BalusC

实际上宁愿使用 ExecutorService 而不是 Timer,这里有一个 SSCCE

package com.stackoverflow.q2275443;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public class Test {
    public static void main(String[] args) throws Exception {
        ExecutorService executor = Executors.newSingleThreadExecutor();
        Future<String> future = executor.submit(new Task());

        try {
            System.out.println("Started..");
            System.out.println(future.get(3, TimeUnit.SECONDS));
            System.out.println("Finished!");
        } catch (TimeoutException e) {
            future.cancel(true);
            System.out.println("Terminated!");
        }

        executor.shutdownNow();
    }
}

class Task implements Callable<String> {
    @Override
    public String call() throws Exception {
        Thread.sleep(4000); // Just to demo a long running task of 4 seconds.
        return "Ready!";
    }
}

Future#get() 方法中使用 timeout 参数,例如将其增加到 5,您会看到线程完成。您可以在 catch (TimeoutException e) 块中拦截超时。

更新:为了澄清概念上的误解,sleep() 不是必需的。它仅用于 SSCCE/演示目的。只需在此处代替 sleep() 执行您的长时间运行的任务。在您长时间运行的任务中,您应该检查线程是否不是 interrupted,如下所示:

while (!Thread.interrupted()) {
    // Do your long running task here.
}

Thread.sleep(4000) 替换为其他一些长时间运行的语句,该示例将不起作用。换言之,此示例Task 旨在理解 Thread.isInterrupted() 状态更改时才有效。
@BalusC 我尝试了这种方法试图终止我的线程,但无法使其工作。您可以在这里查看:stackoverflow.com/questions/35553420/…
由 future.cancel(true) 引起的 InterruptedException 是如何处理的?
有 n 人评论了包名称,这是另一个 +1。吸收这种技能真是太好了。谢谢!
@BalusC我有疑问,未来是否会同步执行,如果它需要超过预定义的时间,那么它将被终止。否则它会在未来的某个时间执行,同时我们正在指望时间......谢谢
e
erickson

对于任何旧任务,都没有 100% 可靠的方法来执行此操作。编写任务时必须考虑到这种能力。

ExecutorService 等核心 Java 库通过工作线程上的 interrupt() 调用取消异步任务。因此,例如,如果任务包含某种循环,您应该在每次迭代时检查它的 interrupt status。如果任务正在执行 I/O 操作,它们也应该是可中断的——而且设置它可能很棘手。无论如何,请记住代码必须主动检查中断;设置中断并不一定会做任何事情。

当然,如果您的任务是一些简单的循环,您可以在每次迭代时检查当前时间,并在指定的超时时间过去后放弃。在这种情况下不需要工作线程。


以我的经验,唯一对开始中断没有反应的代码是阻塞本机代码(等待操作系统)。
@ThorbjørnRavnAndersen 我同意,但这是很多代码。我的观点是没有通用的机制。您必须了解任务的中断策略。
@erickson,我同意你的观点。直截了当的回答,必须为每个任务定义一个取消策略,如果您有兴趣以它的方式停止它。或者线程应该知道它被中断时应该做什么。毕竟,中断和停止任何线程只是目标线程可能接受或拒绝的请求,因此最好在编写任务时牢记这一点。
executorservice 不能选择在调用线程上运行任务吗? executorservice 也可能选择在未来某个时候执行任务?
@user1232726 父接口的 execute() 方法,Executor 可能会在调用线程中运行任务。对于返回 Future 实例的 ExecutorServicesubmit() 方法,没有类似的语句。该服务的含义是必须通过关闭清理工作线程,并且任务是异步执行的。也就是说,合同中没有任何内容表明禁止 ExecutorService 在提交线程中执行任务;这些保证来自实现 API,例如 Executors 工厂。
D
Drew Wills

考虑使用 ExecutorService 的实例。 invokeAll()invokeAny() 方法都可以使用 timeout 参数。

当前线程将阻塞,直到方法完成(不确定这是否可取),因为任务正常完成或达到超时。您可以检查返回的 Future 以确定发生了什么。


R
Ravindra babu

假设线程代码不受您的控制:

从上面提到的 Java documentation

如果线程没有响应 Thread.interrupt 怎么办?在某些情况下,您可以使用特定于应用程序的技巧。例如,如果一个线程正在等待一个已知的套接字,您可以关闭该套接字以使该线程立即返回。不幸的是,实际上没有任何技术可以通用。应该注意的是,在等待线程不响应 Thread.interrupt 的所有情况下,它也不会响应 Thread.stop。此类情况包括故意拒绝服务攻击,以及 thread.stop 和 thread.interrupt 无法正常工作的 I/O 操作。

底线:

确保所有线程都可以被中断,否则您需要线程的特定知识——比如设置一个标志。也许您可以要求将任务连同停止它所需的代码一起提供给您 - 使用 stop() 方法定义一个接口。您还可以在未能停止任务时发出警告。


C
Community

BalusC 说:

更新:为了澄清概念上的误解,不需要 sleep() 。它仅用于 SSCCE/演示目的。只需在此处代替 sleep() 执行您的长时间运行的任务。

但是如果将 Thread.sleep(4000); 替换为 for (int i = 0; i < 5E8; i++) {} 则它不会编译,因为空循环不会抛出 InterruptedException

为了使线程可中断,它需要抛出一个 InterruptedException

这对我来说似乎是一个严重的问题。我看不出如何调整这个答案来处理一般的长时间运行的任务。

编辑添加:我将此作为一个新问题重新提出:[ interrupting a thread after fixed time, does it have to throw InterruptedException? ]


我这样做的方法是在 public Class call {} 方法中添加一个“抛出异常”
D
Dieter

我认为你应该看看适当的并发处理机制(线程运行到无限循环本身听起来并不好,顺便说一句)。请务必阅读有关 "killing" or "stopping" Threads 主题的一些信息。

您所描述的内容听起来很像“集合点”,因此您可能想看看 CyclicBarrier

可能有其他构造(例如使用 CountDownLatch )可以解决您的问题(一个线程等待闩锁超时,另一个线程如果已完成工作则应倒计时闩锁,这将释放您的第一个线程在超时后或调用锁存倒计时时)。

我通常推荐这方面的两本书:Concurrent Programming in JavaJava Concurrency in Practice


j
j0k

我前段时间为此创建了一个助手类。效果很好:

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
/**
 * TimeOut class - used for stopping a thread that is taking too long
 * @author Peter Goransson
 *
 */
public class TimeOut {

    Thread interrupter;
    Thread target;
    long timeout;
    boolean success;
    boolean forceStop;

    CyclicBarrier barrier;

    /**
     * 
     * @param target The Runnable target to be executed
     * @param timeout The time in milliseconds before target will be interrupted or stopped
     * @param forceStop If true, will Thread.stop() this target instead of just interrupt() 
     */
    public TimeOut(Runnable target, long timeout, boolean forceStop) {      
        this.timeout = timeout;
        this.forceStop = forceStop;

        this.target = new Thread(target);       
        this.interrupter = new Thread(new Interrupter());

        barrier = new CyclicBarrier(2); // There will always be just 2 threads waiting on this barrier
    }

    public boolean execute() throws InterruptedException {  

        // Start target and interrupter
        target.start();
        interrupter.start();

        // Wait for target to finish or be interrupted by interrupter
        target.join();  

        interrupter.interrupt(); // stop the interrupter    
        try {
            barrier.await(); // Need to wait on this barrier to make sure status is set
        } catch (BrokenBarrierException e) {
            // Something horrible happened, assume we failed
            success = false;
        } 

        return success; // status is set in the Interrupter inner class
    }

    private class Interrupter implements Runnable {

        Interrupter() {}

        public void run() {
            try {
                Thread.sleep(timeout); // Wait for timeout period and then kill this target
                if (forceStop) {
                  target.stop(); // Need to use stop instead of interrupt since we're trying to kill this thread
                }
                else {
                    target.interrupt(); // Gracefully interrupt the waiting thread
                }
                System.out.println("done");             
                success = false;
            } catch (InterruptedException e) {
                success = true;
            }


            try {
                barrier.await(); // Need to wait on this barrier
            } catch (InterruptedException e) {
                // If the Child and Interrupter finish at the exact same millisecond we'll get here
                // In this weird case assume it failed
                success = false;                
            } 
            catch (BrokenBarrierException e) {
                // Something horrible happened, assume we failed
                success = false;
            }

        }

    }
}

它是这样调用的:

long timeout = 10000; // number of milliseconds before timeout
TimeOut t = new TimeOut(new PhotoProcessor(filePath, params), timeout, true);
try {                       
  boolean sucess = t.execute(); // Will return false if this times out
  if (!sucess) {
    // This thread timed out
  }
  else {
    // This thread ran completely and did not timeout
  }
} catch (InterruptedException e) {}  

e
elou

我向您发布了一段代码,展示了如何解决问题的方法。例如,我正在阅读一个文件。您可以将此方法用于其他操作,但您需要实现 kill() 方法,以便中断主要操作。

希望能帮助到你


import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Main class
 * 
 * @author el
 * 
 */
public class Main {
    /**
     * Thread which perform the task which should be timed out.
     * 
     * @author el
     * 
     */
    public static class MainThread extends Thread {
        /**
         * For example reading a file. File to read.
         */
        final private File fileToRead;
        /**
         * InputStream from the file.
         */
        final private InputStream myInputStream;
        /**
         * Thread for timeout.
         */
        final private TimeOutThread timeOutThread;

        /**
         * true if the thread has not ended.
         */
        boolean isRunning = true;

        /**
         * true if all tasks where done.
         */
        boolean everythingDone = false;

        /**
         * if every thing could not be done, an {@link Exception} may have
         * Happens.
         */
        Throwable endedWithException = null;

        /**
         * Constructor.
         * 
         * @param file
         * @throws FileNotFoundException
         */
        MainThread(File file) throws FileNotFoundException {
            setDaemon(false);
            fileToRead = file;
            // open the file stream.
            myInputStream = new FileInputStream(fileToRead);
            // Instantiate the timeout thread.
            timeOutThread = new TimeOutThread(10000, this);
        }

        /**
         * Used by the {@link TimeOutThread}.
         */
        public void kill() {
            if (isRunning) {
                isRunning = false;
                if (myInputStream != null) {
                    try {
                        // close the stream, it may be the problem.
                        myInputStream.close();
                    } catch (IOException e) {
                        // Not interesting
                        System.out.println(e.toString());
                    }
                }
                synchronized (this) {
                    notify();
                }
            }
        }

        /**
         * The task which should be timed out.
         */
        @Override
        public void run() {
            timeOutThread.start();
            int bytes = 0;
            try {
                // do something
                while (myInputStream.read() >= 0) {
                    // may block the thread.
                    myInputStream.read();
                    bytes++;
                    // simulate a slow stream.
                    synchronized (this) {
                        wait(10);
                    }
                }
                everythingDone = true;
            } catch (IOException e) {
                endedWithException = e;
            } catch (InterruptedException e) {
                endedWithException = e;
            } finally {
                timeOutThread.kill();
                System.out.println("-->read " + bytes + " bytes.");
                isRunning = false;
                synchronized (this) {
                    notifyAll();
                }
            }
        }
    }

    /**
     * Timeout Thread. Kill the main task if necessary.
     * 
     * @author el
     * 
     */
    public static class TimeOutThread extends Thread {
        final long timeout;
        final MainThread controlledObj;

        TimeOutThread(long timeout, MainThread controlledObj) {
            setDaemon(true);
            this.timeout = timeout;
            this.controlledObj = controlledObj;
        }

        boolean isRunning = true;

        /**
         * If we done need the {@link TimeOutThread} thread, we may kill it.
         */
        public void kill() {
            isRunning = false;
            synchronized (this) {
                notify();
            }
        }

        /**
         * 
         */
        @Override
        public void run() {
            long deltaT = 0l;
            try {
                long start = System.currentTimeMillis();
                while (isRunning && deltaT < timeout) {
                    synchronized (this) {
                        wait(Math.max(100, timeout - deltaT));
                    }
                    deltaT = System.currentTimeMillis() - start;
                }
            } catch (InterruptedException e) {
                // If the thread is interrupted,
                // you may not want to kill the main thread,
                // but probably yes.
            } finally {
                isRunning = false;
            }
            controlledObj.kill();
        }
    }

    /**
     * Start the main task and wait for the end.
     * 
     * @param args
     * @throws FileNotFoundException
     */
    public static void main(String[] args) throws FileNotFoundException {
        long start = System.currentTimeMillis();
        MainThread main = new MainThread(new File(args[0]));
        main.start();
        try {
            while (main.isRunning) {
                synchronized (main) {
                    main.wait(1000);
                }
            }
            long stop = System.currentTimeMillis();

            if (main.everythingDone)
                System.out.println("all done in " + (stop - start) + " ms.");
            else {
                System.out.println("could not do everything in "
                        + (stop - start) + " ms.");
                if (main.endedWithException != null)
                    main.endedWithException.printStackTrace();
            }
        } catch (InterruptedException e) {
            System.out.println("You've killed me!");
        }
    }
}

问候


C
Community

这是我真正简单易用帮助类run{2 } 段 Java 代码 :-)

这是基于来自 BalusC 的优秀 answer

package com.mycompany.util.concurrent;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * Calling {@link Callable#call()} or Running {@link Runnable#run()} code
 * with a timeout based on {@link Future#get(long, TimeUnit))}
 * @author pascaldalfarra
 *
 */
public class CallableHelper
{

    private CallableHelper()
    {
    }

    public static final void run(final Runnable runnable, int timeoutInSeconds)
    {
        run(runnable, null, timeoutInSeconds);
    }

    public static final void run(final Runnable runnable, Runnable timeoutCallback, int timeoutInSeconds)
    {
        call(new Callable<Void>()
        {
            @Override
            public Void call() throws Exception
            {
                runnable.run();
                return null;
            }
        }, timeoutCallback, timeoutInSeconds); 
    }

    public static final <T> T call(final Callable<T> callable, int timeoutInSeconds)
    {
        return call(callable, null, timeoutInSeconds); 
    }

    public static final <T> T call(final Callable<T> callable, Runnable timeoutCallback, int timeoutInSeconds)
    {
        ExecutorService executor = Executors.newSingleThreadExecutor();
        try
        {
            Future<T> future = executor.submit(callable);
            T result = future.get(timeoutInSeconds, TimeUnit.SECONDS);
            System.out.println("CallableHelper - Finished!");
            return result;
        }
        catch (TimeoutException e)
        {
            System.out.println("CallableHelper - TimeoutException!");
            if(timeoutCallback != null)
            {
                timeoutCallback.run();
            }
        }
        catch (InterruptedException e)
        {
            e.printStackTrace();
        }
        catch (ExecutionException e)
        {
            e.printStackTrace();
        }
        finally
        {
            executor.shutdownNow();
            executor = null;
        }

        return null;
    }

}

S
Sumeet Sahu

BalusC 给出的解决方案中,主线程将在超时期间保持阻塞。如果您的线程池包含多个线程,则您将需要相同数量的附加线程,这些线程将使用 Future.get(long timeout,TimeUnit unit) 阻塞调用来等待并在超过超时期限时关闭线程。

此问题的通用解决方案是创建一个可以添加超时功能的 ThreadPoolExecutor 装饰器。这个 Decorator 类应该创建与 ThreadPoolExecutor 一样多的线程,并且所有这些线程应该只用于等待和关闭 ThreadPoolExecutor。

泛型类应该如下实现:

import java.util.List;
import java.util.concurrent.*;

public class TimeoutThreadPoolDecorator extends ThreadPoolExecutor {


    private final ThreadPoolExecutor commandThreadpool;
    private final long timeout;
    private final TimeUnit unit;

    public TimeoutThreadPoolDecorator(ThreadPoolExecutor threadpool,
                                      long timeout,
                                      TimeUnit unit ){
        super(  threadpool.getCorePoolSize(),
                threadpool.getMaximumPoolSize(),
                threadpool.getKeepAliveTime(TimeUnit.MILLISECONDS),
                TimeUnit.MILLISECONDS,
                threadpool.getQueue());

        this.commandThreadpool = threadpool;
        this.timeout=timeout;
        this.unit=unit;
    }

    @Override
    public void execute(Runnable command) {
        super.execute(() -> {
            Future<?> future = commandThreadpool.submit(command);
            try {
                future.get(timeout, unit);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            } catch (ExecutionException | TimeoutException e) {
                throw new RejectedExecutionException(e);
            } finally {
                future.cancel(true);
            }
        });
    }

    @Override
    public void setCorePoolSize(int corePoolSize) {
        super.setCorePoolSize(corePoolSize);
        commandThreadpool.setCorePoolSize(corePoolSize);
    }

    @Override
    public void setThreadFactory(ThreadFactory threadFactory) {
        super.setThreadFactory(threadFactory);
        commandThreadpool.setThreadFactory(threadFactory);
    }

    @Override
    public void setMaximumPoolSize(int maximumPoolSize) {
        super.setMaximumPoolSize(maximumPoolSize);
        commandThreadpool.setMaximumPoolSize(maximumPoolSize);
    }

    @Override
    public void setKeepAliveTime(long time, TimeUnit unit) {
        super.setKeepAliveTime(time, unit);
        commandThreadpool.setKeepAliveTime(time, unit);
    }

    @Override
    public void setRejectedExecutionHandler(RejectedExecutionHandler handler) {
        super.setRejectedExecutionHandler(handler);
        commandThreadpool.setRejectedExecutionHandler(handler);
    }

    @Override
    public List<Runnable> shutdownNow() {
        List<Runnable> taskList = super.shutdownNow();
        taskList.addAll(commandThreadpool.shutdownNow());
        return taskList;
    }

    @Override
    public void shutdown() {
        super.shutdown();
        commandThreadpool.shutdown();
    }
}

上面的装饰器可以如下使用:

import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class Main {

    public static void main(String[] args){

        long timeout = 2000;

        ThreadPoolExecutor threadPool = new ThreadPoolExecutor(3, 10, 0, TimeUnit.MILLISECONDS, new SynchronousQueue<>(true));

        threadPool = new TimeoutThreadPoolDecorator( threadPool ,
                timeout,
                TimeUnit.MILLISECONDS);


        threadPool.execute(command(1000));
        threadPool.execute(command(1500));
        threadPool.execute(command(2100));
        threadPool.execute(command(2001));

        while(threadPool.getActiveCount()>0);
        threadPool.shutdown();


    }

    private static Runnable command(int i) {

        return () -> {
            System.out.println("Running Thread:"+Thread.currentThread().getName());
            System.out.println("Starting command with sleep:"+i);
            try {
                Thread.sleep(i);
            } catch (InterruptedException e) {
                System.out.println("Thread "+Thread.currentThread().getName()+" with sleep of "+i+" is Interrupted!!!");
                return;
            }
            System.out.println("Completing Thread "+Thread.currentThread().getName()+" after sleep of "+i);
        };

    }
}

m
markusk

以下代码段将在单独的线程中启动操作,然后等待最多 10 秒以完成操作。如果操作没有及时完成,代码将尝试取消操作,然后继续其愉快的方式。即使操作不能轻易取消,父线程也不会等待子线程终止。

ExecutorService executorService = getExecutorService();
Future<SomeClass> future = executorService.submit(new Callable<SomeClass>() {
    public SomeClass call() {
        // Perform long-running task, return result. The code should check
        // interrupt status regularly, to facilitate cancellation.
    }
});
try {
    // Real life code should define the timeout as a constant or
    // retrieve it from configuration
    SomeClass result = future.get(10, TimeUnit.SECONDS);
    // Do something with the result
} catch (TimeoutException e) {
    future.cancel(true);
    // Perform other error handling, e.g. logging, throwing an exception
}

getExecutorService() 方法可以通过多种方式实现。如果您没有任何特殊要求,您可以简单地调用 Executors.newCachedThreadPool() 进行线程池,线程数没有上限。


需要进口什么? SomeClassFuture 是什么?
C
Cacovsky

我没有看到提到的一件事是杀死线程通常是一个坏主意。有一些技术可以使线程方法完全可中止,但这与在超时后终止线程不同。

你所建议的风险是你可能不知道当你杀死它时线程会处于什么状态 - 所以你有引入不稳定的风险。更好的解决方案是确保您的线程代码不会自行挂起,或者会很好地响应中止请求。


如果没有上下文,像你这样的陈述听起来太严格了。在学术环境中,我经常需要在超时之前测试某些东西,当它发生时,我只需放弃所有计算并记录超时发生。可能这在行业中很少见,但仍然......
@AlessandroS:这是一个合理的观点,尽管 OP 要求“更好的解决方案”,我认为这意味着稳健性和可靠性优于蛮力。
R
Robocide

BalusC 的出色回答:

但只是补充一点,超时本身不会中断线程本身。即使您在任务中使用 while(!Thread.interrupted()) 检查。如果要确保线程停止,还应确保在捕获超时异常时调用 future.cancel()。

package com.stackoverflow.q2275443; 

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;


public class Test { 
    public static void main(String[] args) throws Exception {
        ExecutorService executor = Executors.newSingleThreadExecutor();
        Future<String> future = executor.submit(new Task());

        try { 
            System.out.println("Started..");
            System.out.println(future.get(3, TimeUnit.SECONDS));
            System.out.println("Finished!");
        } catch (TimeoutException e) {
            //Without the below cancel the thread will continue to live 
            // even though the timeout exception thrown.
            future.cancel();
            System.out.println("Terminated!");
        } 

        executor.shutdownNow();
    } 
} 

class Task implements Callable<String> {
    @Override 
    public String call() throws Exception {
      while(!Thread.currentThread.isInterrupted()){
          System.out.println("Im still running baby!!");
      }          
    } 
} 

s
sfussenegger

我认为答案主要取决于任务本身。

它是一遍又一遍地完成一项任务吗?

是否有必要在超时后立即中断当前正在运行的任务?

如果第一个答案是肯定的,而第二个答案是否定的,你可以把它保持得这么简单:

public class Main {

    private static final class TimeoutTask extends Thread {
        private final long _timeoutMs;
        private Runnable _runnable;

        private TimeoutTask(long timeoutMs, Runnable runnable) {
            _timeoutMs = timeoutMs;
            _runnable = runnable;
        }

        @Override
        public void run() {
            long start = System.currentTimeMillis();
            while (System.currentTimeMillis() < (start + _timeoutMs)) {
                _runnable.run();
            }
            System.out.println("execution took " + (System.currentTimeMillis() - start) +" ms");
        }

    }

    public static void main(String[] args) throws Exception {
        new TimeoutTask(2000L, new Runnable() {

            @Override
            public void run() {
                System.out.println("doing something ...");
                try {
                    // pretend it's taking somewhat longer than it really does
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }
        }).start();
    }
}

如果这不是一个选项,请缩小您的要求 - 或显示一些代码。


T
Tom

我一直在寻找一个 ExecutorService 可以中断它执行的所有超时 Runnables,但没有找到。几个小时后,我创建了一个如下。可以修改此类以增强鲁棒性。

public class TimedExecutorService extends ThreadPoolExecutor {
    long timeout;
    public TimedExecutorService(int numThreads, long timeout, TimeUnit unit) {
        super(numThreads, numThreads, 0L, TimeUnit.MILLISECONDS, new ArrayBlockingQueue<Runnable>(numThreads + 1));
        this.timeout = unit.toMillis(timeout);
    }

    @Override
    protected void beforeExecute(Thread thread, Runnable runnable) {
        Thread interruptionThread = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    // Wait until timeout and interrupt this thread
                    Thread.sleep(timeout);
                    System.out.println("The runnable times out.");
                    thread.interrupt();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });
        interruptionThread.start();
    }
}

用法:

public static void main(String[] args) {

    Runnable abcdRunnable = new Runnable() {
        @Override
        public void run() {
            System.out.println("abcdRunnable started");
            try {
                Thread.sleep(20000);
            } catch (InterruptedException e) {
                // logger.info("The runnable times out.");
            }
            System.out.println("abcdRunnable ended");
        }
    };

    Runnable xyzwRunnable = new Runnable() {
        @Override
        public void run() {
            System.out.println("xyzwRunnable started");
            try {
                Thread.sleep(20000);
            } catch (InterruptedException e) {
                // logger.info("The runnable times out.");
            }
            System.out.println("xyzwRunnable ended");
        }
    };

    int numThreads = 2, timeout = 5;
    ExecutorService timedExecutor = new TimedExecutorService(numThreads, timeout, TimeUnit.SECONDS);
    timedExecutor.execute(abcdRunnable);
    timedExecutor.execute(xyzwRunnable);
    timedExecutor.shutdown();
}

L
Liu Jing

现在,我遇到了这样的问题。它碰巧解码图片。解码过程花费了太多时间,屏幕保持黑色。 l 添加时间控制器:当时间过长时,从当前线程中弹出。以下是差异:

   ExecutorService executor = Executors.newSingleThreadExecutor();
   Future<Bitmap> future = executor.submit(new Callable<Bitmap>() {
       @Override
       public Bitmap call() throws Exception {
       Bitmap bitmap = decodeAndScaleBitmapFromStream(context, inputUri);// do some time consuming operation
       return null;
            }
       });
       try {
           Bitmap result = future.get(1, TimeUnit.SECONDS);
       } catch (TimeoutException e){
           future.cancel(true);
       }
       executor.shutdown();
       return (bitmap!= null);

N
Niroshan Abeywickrama

我有同样的问题。所以我想出了一个像这样的简单解决方案。

public class TimeoutBlock {

 private final long timeoutMilliSeconds;
    private long timeoutInteval=100;

    public TimeoutBlock(long timeoutMilliSeconds){
        this.timeoutMilliSeconds=timeoutMilliSeconds;
    }

    public void addBlock(Runnable runnable) throws Throwable{
        long collectIntervals=0;
        Thread timeoutWorker=new Thread(runnable);
        timeoutWorker.start();
        do{ 
            if(collectIntervals>=this.timeoutMilliSeconds){
                timeoutWorker.stop();
                throw new Exception("<<<<<<<<<<****>>>>>>>>>>> Timeout Block Execution Time Exceeded In "+timeoutMilliSeconds+" Milli Seconds. Thread Block Terminated.");
            }
            collectIntervals+=timeoutInteval;           
            Thread.sleep(timeoutInteval);

        }while(timeoutWorker.isAlive());
        System.out.println("<<<<<<<<<<####>>>>>>>>>>> Timeout Block Executed Within "+collectIntervals+" Milli Seconds.");
    }

    /**
     * @return the timeoutInteval
     */
    public long getTimeoutInteval() {
        return timeoutInteval;
    }

    /**
     * @param timeoutInteval the timeoutInteval to set
     */
    public void setTimeoutInteval(long timeoutInteval) {
        this.timeoutInteval = timeoutInteval;
    }
}

保证如果块没有在时间限制内执行。该进程将终止并引发异常。

例子 :

try {
        TimeoutBlock timeoutBlock = new TimeoutBlock(10 * 60 * 1000);//set timeout in milliseconds
        Runnable block=new Runnable() {

            @Override
            public void run() {
                //TO DO write block of code 
            }
        };

        timeoutBlock.addBlock(block);// execute the runnable block 

    } catch (Throwable e) {
        //catch the exception here . Which is block didn't execute within the time limit
    }