处理来自Java ExecutorService任务的异常

我试图使用Java的

ThreadPoolExecutor

类来运行大量具有固定线程数的重载任务。每个任务都有许多地方，在此期间可能会由于异常而失败

我对

ThreadPoolExecutor

进行了子类化，并重写了

afterExecute

方法，该方法应该提供在运行任务时遇到的任何未捕获异常。然而，我似乎无法让它工作

例如：

public class ThreadPoolErrors extends ThreadPoolExecutor {
    public ThreadPoolErrors() {
        super(  1, // core threads
                1, // max threads
                1, // timeout
                TimeUnit.MINUTES, // timeout units
                new LinkedBlockingQueue<Runnable>() // work queue
        );
    }

    protected void afterExecute(Runnable r, Throwable t) {
        super.afterExecute(r, t);
        if(t != null) {
            System.out.println("Got an error: " + t);
        } else {
            System.out.println("Everything's fine--situation normal!");
        }
    }

    public static void main( String [] args) {
        ThreadPoolErrors threadPool = new ThreadPoolErrors();
        threadPool.submit( 
                new Runnable() {
                    public void run() {
                        throw new RuntimeException("Ouch! Got an error.");
                    }
                }
        );
        threadPool.shutdown();
    }
}

import com.jcabi.log.VerboseRunnable;
scheduler.scheduleWithFixedDelay(
  new VerboseRunnable(
    Runnable() {
      public void run() { 
        // the code, which may throw
      }
    },
    true // it means that all exceptions will be swallowed and logged
  ),
  1, 1, TimeUnit.MILLISECONDS
);

公共类ThreadPoolErrors扩展ThreadPoolExecutor{
公共线程池错误（）{
超级（1，//核心线程
1，//最大线程数
1，//超时
TimeUnit.MINUTES，//超时单位
新建LinkedBlockingQueue（）//工作队列
);
}
执行后受保护的无效（可运行的r、可丢弃的t）{
super.afterExecute（r，t）；
如果（t！=null）{
System.out.println（“出现错误：+t”）；
}否则{
System.out.println（“一切正常，情况正常！”）；
}
}
公共静态void main（字符串[]args）{
ThreadPoolErrors threadPool=新的ThreadPoolErrors（）；
线程池。提交（
新的Runnable（）{
公开募捐{
抛出新的RuntimeException（“哎哟！出错了。”）；
}
}
);
threadPool.shutdown（）；
}
}

该程序的输出是“一切正常——情况正常！”，即使提交到线程池的唯一可运行程序抛出异常。这里发生了什么有线索吗

谢谢

警告：应该注意，此解决方案将阻止调用线程

---

如果要处理任务引发的异常，通常最好使用

Callable

，而不是

Runnable

Callable.call（）

允许抛出已检查的异常，这些异常会传播回调用线程：

Callable task = ...
Future future = executor.submit(task);
try {
   future.get();
} catch (ExecutionException ex) {
   ex.getCause().printStackTrace();
}

如果

Callable.call（）

引发异常，则该异常将包装在

ExecutionException

中，并由

Future.get（）引发

这可能比子类化
ThreadPoolExecutor
要好得多。如果异常是可恢复的，您还可以重新提交任务。
我将为它提供一个创建新线程的实例，并从以下位置为它们提供一个
，而不是子类化ThreadPoolExecutor：

注意：当动作包含在
任务（如FutureTask）或
显式地或通过诸如
提交时，这些任务对象捕获并
维护计算异常，以及
因此，它们不会导致突然的
终止，以及内部
例外情况不会传递给此
方法

当您提交Runnable时，它将被包装在未来

您的afterExecute应该是这样的：

public final class ExtendedExecutor extends ThreadPoolExecutor {

    // ...

    protected void afterExecute(Runnable r, Throwable t) {
        super.afterExecute(r, t);
        if (t == null && r instanceof Future<?>) {
            try {
                Future<?> future = (Future<?>) r;
                if (future.isDone()) {
                    future.get();
                }
            } catch (CancellationException ce) {
                t = ce;
            } catch (ExecutionException ee) {
                t = ee.getCause();
            } catch (InterruptedException ie) {
                Thread.currentThread().interrupt();
            }
        }
        if (t != null) {
            System.out.println(t);
        }
    }
}

公共最终类ExtendedExecutor扩展ThreadPoolExecutor{
// ...
执行后受保护的无效（可运行的r、可丢弃的t）{
super.afterExecute（r，t）；
if（t==null&&r未来实例）{
试一试{
未来=（未来）r；
if（future.isDone（））{
future.get（）；
}
}捕获（取消异常）{
t=ce；
}捕获（被执行者）{
t=ee.getCause（）；
}捕获（中断异常ie）{
Thread.currentThread（）.interrupt（）；
}
}
如果（t！=null）{
系统输出打印ln（t）；
}
}
}
对这种行为的解释如下：

注意：当动作包含在
任务（如FutureTask）或
显式地或通过诸如
提交时，这些任务对象捕获并
维护计算异常，以及
因此，它们不会导致突然的
终止，以及内部
例外情况不会传递给此
方法

我使用的是from类，它会吞并所有异常并记录它们。非常方便，例如：

public class ThreadPoolErrors extends ThreadPoolExecutor {
    public ThreadPoolErrors() {
        super(  1, // core threads
                1, // max threads
                1, // timeout
                TimeUnit.MINUTES, // timeout units
                new LinkedBlockingQueue<Runnable>() // work queue
        );
    }

    protected void afterExecute(Runnable r, Throwable t) {
        super.afterExecute(r, t);
        if(t != null) {
            System.out.println("Got an error: " + t);
        } else {
            System.out.println("Everything's fine--situation normal!");
        }
    }

    public static void main( String [] args) {
        ThreadPoolErrors threadPool = new ThreadPoolErrors();
        threadPool.submit( 
                new Runnable() {
                    public void run() {
                        throw new RuntimeException("Ouch! Got an error.");
                    }
                }
        );
        threadPool.shutdown();
    }
}

import com.jcabi.log.VerboseRunnable;
scheduler.scheduleWithFixedDelay(
  new VerboseRunnable(
    Runnable() {
      public void run() { 
        // the code, which may throw
      }
    },
    true // it means that all exceptions will be swallowed and logged
  ),
  1, 1, TimeUnit.MILLISECONDS
);

我通过包装提交给执行人的runnable文件来解决这个问题

CompletableFuture.runAsync(() -> {
        try {
              runnable.run();
        } catch (Throwable e) {
              Log.info(Concurrency.class, "runAsync", e);
        }
}, executorService);

如果您的
ExecutorService
来自外部源（即无法对
ThreadPoolExecutor
子类化并重写
afterExecute（）
），则可以使用动态代理来实现所需的行为：

public static ExecutorService errorAware(final ExecutorService executor) {
    return (ExecutorService) Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),
            new Class[] {ExecutorService.class},
            (proxy, method, args) -> {
                if (method.getName().equals("submit")) {
                    final Object arg0 = args[0];
                    if (arg0 instanceof Runnable) {
                        args[0] = new Runnable() {
                            @Override
                            public void run() {
                                final Runnable task = (Runnable) arg0;
                                try {
                                    task.run();
                                    if (task instanceof Future<?>) {
                                        final Future<?> future = (Future<?>) task;

                                        if (future.isDone()) {
                                            try {
                                                future.get();
                                            } catch (final CancellationException ce) {
                                                // Your error-handling code here
                                                ce.printStackTrace();
                                            } catch (final ExecutionException ee) {
                                                // Your error-handling code here
                                                ee.getCause().printStackTrace();
                                            } catch (final InterruptedException ie) {
                                                Thread.currentThread().interrupt();
                                            }
                                        }
                                    }
                                } catch (final RuntimeException re) {
                                    // Your error-handling code here
                                    re.printStackTrace();
                                    throw re;
                                } catch (final Error e) {
                                    // Your error-handling code here
                                    e.printStackTrace();
                                    throw e;
                                }
                            }
                        };
                    } else if (arg0 instanceof Callable<?>) {
                        args[0] = new Callable<Object>() {
                            @Override
                            public Object call() throws Exception {
                                final Callable<?> task = (Callable<?>) arg0;
                                try {
                                    return task.call();
                                } catch (final Exception e) {
                                    // Your error-handling code here
                                    e.printStackTrace();
                                    throw e;
                                } catch (final Error e) {
                                    // Your error-handling code here
                                    e.printStackTrace();
                                    throw e;
                                }
                            }
                        };
                    }
                }
                return method.invoke(executor, args);
            });
}

公共静态执行器服务errorAware（最终执行器服务执行器）{
return（ExecutorService）Proxy.newProxyInstance（Thread.currentThread（）.getContextClassLoader（），
新类[]{ExecutorService.Class}，
（代理、方法、参数）->{
if（method.getName（）.equals（“提交”））{
最终对象arg0=args[0]；
如果（arg0 instanceof Runnable）{
args[0]=新的可运行（）{
@凌驾
公开募捐{
最终可运行任务=（可运行）arg0；
试一试{
task.run（）；
if（未来的任务实例）{
最终未来=（未来）任务；
if（future.isDone（））{
试一试{
future.get（）；
}捕获（最终取消异常ce）{
//您的错误处理代码在这里
printStackTrace（）；
}捕获（最终被执行人）{
//你的错误
AbstractExecutorService.java

public Future<?> submit(Runnable task) {
    if (task == null) throw new NullPointerException();
    RunnableFuture<Void> ftask = newTaskFor(task, null); /////////HERE////////
    execute(ftask);
    return ftask;
}

ThreadPoolExecutor.java

final void runWorker(Worker w) {
    Thread wt = Thread.currentThread();
    Runnable task = w.firstTask;
    w.firstTask = null;
    w.unlock(); // allow interrupts
    boolean completedAbruptly = true;
    try {
        while (task != null || (task = getTask()) != null) {
            w.lock();
            // If pool is stopping, ensure thread is interrupted;
            // if not, ensure thread is not interrupted.  This
            // requires a recheck in second case to deal with
            // shutdownNow race while clearing interrupt
            if ((runStateAtLeast(ctl.get(), STOP) ||
                 (Thread.interrupted() &&
                  runStateAtLeast(ctl.get(), STOP))) &&
                !wt.isInterrupted())
                wt.interrupt();
            try {
                beforeExecute(wt, task);
                Throwable thrown = null;
                try {
                    task.run();           /////////HERE////////
                } catch (RuntimeException x) {
                    thrown = x; throw x;
                } catch (Error x) {
                    thrown = x; throw x;
                } catch (Throwable x) {
                    thrown = x; throw new Error(x);
                } finally {
                    afterExecute(task, thrown);
                }
            } finally {
                task = null;
                w.completedTasks++;
                w.unlock();
            }
        }
        completedAbruptly = false;
    } finally {
        processWorkerExit(w, completedAbruptly);
    }
}

class FutureTask<V> implements RunnableFuture<V>

public void run() {
    if (state != NEW ||
        !UNSAFE.compareAndSwapObject(this, runnerOffset,
                                     null, Thread.currentThread()))
        return;
    try {
        Callable<V> c = callable;
        if (c != null && state == NEW) {
            V result;
            boolean ran;
            try {
                result = c.call();
                ran = true;
            } catch (Throwable ex) {   /////////HERE////////
                result = null;
                ran = false;
                setException(ex);
            }
            if (ran)
                set(result);
        }
    } finally {
        // runner must be non-null until state is settled to
        // prevent concurrent calls to run()
        runner = null;
        // state must be re-read after nulling runner to prevent
        // leaked interrupts
        int s = state;
        if (s >= INTERRUPTING)
            handlePossibleCancellationInterrupt(s);
    }
}

public final class SingleThreadExecutorWithExceptions {

    public static ExecutorService newSingleThreadExecutorWithExceptions(final Thread.UncaughtExceptionHandler uncaughtExceptionHandler) {

        ThreadFactory factory = (Runnable runnable)  -> {
            final Thread newThread = new Thread(runnable, "SingleThreadExecutorWithExceptions");
            newThread.setUncaughtExceptionHandler( (final Thread caugthThread,final Throwable throwable) -> {
                uncaughtExceptionHandler.uncaughtException(caugthThread, throwable);
            });
            return newThread;
        };
        return new FinalizableDelegatedExecutorService
                (new ThreadPoolExecutor(1, 1,
                        0L, TimeUnit.MILLISECONDS,
                        new LinkedBlockingQueue(),
                        factory){


                    protected void afterExecute(Runnable runnable, Throwable throwable) {
                        super.afterExecute(runnable, throwable);
                        if (throwable == null && runnable instanceof Future) {
                            try {
                                Future future = (Future) runnable;
                                if (future.isDone()) {
                                    future.get();
                                }
                            } catch (CancellationException ce) {
                                throwable = ce;
                            } catch (ExecutionException ee) {
                                throwable = ee.getCause();
                            } catch (InterruptedException ie) {
                                Thread.currentThread().interrupt(); // ignore/reset
                            }
                        }
                        if (throwable != null) {
                            uncaughtExceptionHandler.uncaughtException(Thread.currentThread(),throwable);
                        }
                    }
                });
    }



    private static class FinalizableDelegatedExecutorService
            extends DelegatedExecutorService {
        FinalizableDelegatedExecutorService(ExecutorService executor) {
            super(executor);
        }
        protected void finalize() {
            super.shutdown();
        }
    }

    /**
     * A wrapper class that exposes only the ExecutorService methods
     * of an ExecutorService implementation.
     */
    private static class DelegatedExecutorService extends AbstractExecutorService {
        private final ExecutorService e;
        DelegatedExecutorService(ExecutorService executor) { e = executor; }
        public void execute(Runnable command) { e.execute(command); }
        public void shutdown() { e.shutdown(); }
        public List shutdownNow() { return e.shutdownNow(); }
        public boolean isShutdown() { return e.isShutdown(); }
        public boolean isTerminated() { return e.isTerminated(); }
        public boolean awaitTermination(long timeout, TimeUnit unit)
                throws InterruptedException {
            return e.awaitTermination(timeout, unit);
        }
        public Future submit(Runnable task) {
            return e.submit(task);
        }
        public  Future submit(Callable task) {
            return e.submit(task);
        }
        public  Future submit(Runnable task, T result) {
            return e.submit(task, result);
        }
        public  List> invokeAll(Collection> tasks)
                throws InterruptedException {
            return e.invokeAll(tasks);
        }
        public  List> invokeAll(Collection> tasks,
                                             long timeout, TimeUnit unit)
                throws InterruptedException {
            return e.invokeAll(tasks, timeout, unit);
        }
        public  T invokeAny(Collection> tasks)
                throws InterruptedException, ExecutionException {
            return e.invokeAny(tasks);
        }
        public  T invokeAny(Collection> tasks,
                               long timeout, TimeUnit unit)
                throws InterruptedException, ExecutionException, TimeoutException {
            return e.invokeAny(tasks, timeout, unit);
        }
    }



    private SingleThreadExecutorWithExceptions() {}
}
public abstract Task implements Runnable {

    public abstract void execute();

    public void run() {
      try {
        execute();
      } catch (Throwable t) {
        // handle it  
      }
    }
}


public MySampleTask extends Task {
    public void execute() {
        // heavy, error-prone code here
    }
}