Question

我正在使用invokeAll（）调用线程列表。只有当所有线程完成其任务时，AFAIK invokeAll（）才会返回。

ExecutorService threadExecutor = Executors.newFixedThreadPool(getThreadSize());
List<Future<Object>> future = w_threadExecutor.invokeAll(threadList);

当所有线程完成时调用

for (Future<Object> w_inProgressThread : w_future)
{
//

它会停止发生异常的线程而不是剩余的线程。有没有办法在任何线程抛出异常时停止所有其他线程？或者我必须提交每个任务而不是invokeAll（）??

我尝试在invokeAll（）上使用invokeAny（），但不会取消剩余的任务 invokeAny（）：如果其中一个任务完成（或抛出异常），其余的Callable将被取消。参考：http://tutorials.jenkov.com/java-util-concurrent/executorservice.html

更新：

CompletionService<Object> completionService = new ExecutorCompletionService<Object>(w_threadExecutor);
                List<Future<Object>> futures = new ArrayList<Future<Object>>();
                for(Thread w_mt : threadList)
                {
                 futures.add(completionService.submit(w_mt));
                }
                for (int numTaken = 0; numTaken < futures.size(); numTaken++) {
                    Future f = completionService.take();
                    try {
                      Object result = f.get();
                      System.out.println(result);  // do something with the normal result
                    } catch (Exception e) {
                      System.out.println("Catched ExecutionException, shutdown now!");
                      //threadExecutor.shutdownNow();
                      Thread.currentThread().interrupt();

                      for (Future<Object> inProgressThread : futures)
                         {
                             inProgressThread.cancel(true);
                         } 
                      break;
                    }

更新1：

正如waltersu所建议我试过

ExecutorService threadExecutor = Executors.newFixedThreadPool(3);
              CompletionService<Object> completionService = new ExecutorCompletionService<Object>(threadExecutor);
              List<Future<Object>> futures = new ArrayList<Future<Object>>();
              futures.add(completionService.submit(new Callable<Object>() {
                @Override
                public Object call() throws Exception {
                    String s=null;
                //  Thread.sleep(1000);
                  for(int i=0; i < 1000000; i++){
                        int j =10 ;
                        if(i==100)
                        {

                        s.toString();
                        }

                        System.out.println("dazfczdsa :: " + i);
                    }
                  //throw new Exception("This is an expected Exception");
                return s;
                }
              }));
              futures.add(completionService.submit(new Callable<Object>() {
                @Override
                public Object call() throws Exception {
                    for(int i=0; i < 1000000; i++){
                        int j =0 ;
                        j= j+2;
                        System.out.println("dasa :: " + i);
                    }
                  Thread.sleep(3000);

                  return "My First Result";
                }
              }));

              while (futures.size() > 0) {
                Future f = completionService.take();
                futures.remove(f);
                try {
                  Object result = f.get();
                  System.out.println(result);  // do something with the normal result
                } catch (ExecutionException e) {
                  System.out.println("Caught exception from one task: " + e.getCause().getMessage() + ". shutdown now!");
                  f.cancel(true);
                  threadExecutor.shutdownNow();
                  break;
                }
              }
              System.out.println("Main exists");

发生异常时不会停止

Answer 1

您必须逐个提交（），而不是 invokeAll（），然后检查 Future 是否有异常。

public static void main(String[] args) throws InterruptedException {
  ExecutorService threadExecutor = Executors.newFixedThreadPool(3);
  CompletionService<Object> completionService = new ExecutorCompletionService<>(threadExecutor);
  List<Future<Object>> futures = new ArrayList<>();
  futures.add(completionService.submit(new Callable<Object>() {
    @Override
    public Object call() throws Exception {
      Thread.sleep(1000);
      throw new Exception("This is an expected Exception");
    }
  }));
  futures.add(completionService.submit(new Callable<Object>() {
    @Override
    public Object call() throws Exception {
      Thread.sleep(3000);
      return "My First Result";
    }
  }));

  while (futures.size() > 0) {
    Future f = completionService.take();
    futures.remove(f);
    try {
      Object result = f.get();
      System.out.println(result);  // do something with the normal result
    } catch (ExecutionException e) {
      System.out.println("Caught exception from one task: " + e.getCause().getMessage() + ". shutdown now!");
      threadExecutor.shutdownNow();
      break;
    }
  }
  System.out.println("Main exists");
}

更新1 :(回答操作的更新1问题）

那是因为你的任务有一个长循环，不会检查中断，这使你的任务不可取消。那你怎么阻止它？我认为您必须修改其他任务以使其可取消。正如the official doc所说：

如果一个线程长时间没有调用抛出InterruptedException的方法怎么办？然后它必须定期调用Thread.interrupted，如果收到中断，则返回true。例如：

for (int i = 0; i < inputs.length; i++) {
    heavyCrunch(inputs[i]);
    if (Thread.interrupted()) {
        // We've been interrupted: no more crunching.
        return;
    }
}

如果您不想修改任务并希望快速停止，该怎么办？有一种方法可以阻止非可扩展的线程。它是 Thread.stop（）。但是，首先，您无法在不使用反射的情况下从线程池获取线程。此外，它被弃用了，因为＆＃34;它本质上是不安全的＆＃34;根据{{3}}。

所以，最好的做法（我认为）是检查你的任务（或部分代码）的中断，这是不可取消的，并且花费很长时间才能完成。

Answer 2

for(Future<Object> fut : future){
    try {
            System.out.println(fut.get());
    } 
    catch (InterruptedException | ExecutionException e) {
        Thread.currentThread().interrupt();
        // or notify all here
    }

Answer 3

你可以调用Wrappers来获取你的work-runnables以及对它们将被调用的Executor的引用。例外，您可以在run（）中立即关闭。

class ExceptionHandlingWrapper implements Runnable{
    private ExecutorService es;
    private Runnable childRunnable;

    // CTOR taking an ExecutorService and a Runnable
    public ExceptionHandlingWrapper ( ExecutorService es, Runnable work ){
         this.es = es;
         this.childRunnable = work;
    }

    @Override public void run(){
        try{
           childRunnable.run();
        }
        catch(Exception ex){
            // Todo: LOG IT!
            es.shutdownNow();
        }
    }
}

当然，这也适用于Callables。

Answer 4

很少有建议：

移除invokeAll并将所有任务提交至ExecutorService。
从Future上的get（）中捕获异常并使用shutdown＆amp; shutdownNow正如这些问题中所述：

How to stop next thread from running in a ScheduledThreadPoolExecutor

How to forcefully shutdown java ExecutorService

如果线程列表中的任何线程发生异常，则中断所有线程

4 个答案: