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如果在执行Future.get（）时遇到InterruptedException，为什么还要执行Future.cancel（）

[英]Why should I do Future.cancel() if I get InterruptedException when doing Future.get()

原文 2015-08-13 11:28:08 6 1 java/ multithreading/ concurrency

It is stated in Java Concurrency in Practice (Brian Goetz) (highlights are mine): 在Java并发实践（Brian Goetz）中有说明 （重点是我的）：

When Future.get throws InterruptedExcetion or TimeoutException and you know that the result is no longer needed by the program, cancel the task with Future.cancel 当Future.get抛出InterruptedExcetion或TimeoutException并且您知道程序不再需要结果时，请使用Future.cancel取消任务。

Javadoc for Future.get states that (highlight are mine): Javadoc for Future.get指出（重点是我的）：

throws InterruptedException - if the current thread was interrupted while waiting 引发InterruptedException-如果当前线程在等待时被中断

So, as far as I understand: if I get an InterruptedException then my task hasn't been started yet (because the executing thread was interrupted while waiting ). 因此，据我了解：如果收到InterruptedException，则我的任务尚未启动（因为正在等待的执行线程被中断了 ）。 Then why do I have to cancel my task? 那为什么我必须取消我的任务？

1 个解决方案

Waiting in 等待中

throws InterruptedException - if the current thread was interrupted while waiting 引发InterruptedException-如果当前线程在等待时被中断

means that the current running thread (the one executing Future.get() ) was waiting for Future.get() to return. 表示当前正在运行的线程（执行Future.get()那个线程）正在等待Future.get()返回。 In general when a thread waits, it is like waiting to acquire an explicit lock , Object.wait() or for a blocking method in BlockingQueue . 通常，当线程等待时，就像等待获取显式锁 Object.wait()或在BlockingQueue获取阻塞方法一样。

Now about the quote from the book: if your current thread is interrupted (thus the InterruptedException ) and you interpret this as an abrupt cancellation, that you probably do not care anymore what the future will return, so should stop whatever the future does. 现在看书中的引文：如果您当前的线程被中断（因此InterruptedException ），并且您将此解释为突然取消，则您可能不再在乎将来会返回什么，因此应该停止将来所做的一切。

So you are wrong when you tell that the Thread hasn't been started. 因此，当您告诉线程尚未启动时，您就错了。