ExecutorService workStealingPool 和取消方法

您能想到为什么这段代码不起作用并且总是输出“完成”，但第二个示例可以正常工作的任何原因吗？我正在使用最新的 JDK (8u45)。

public static class MyClass implements Runnable {

        @Override
        public void run() {
            try {
                Thread.sleep(2000);
            } catch (InterruptedException ex) {
                System.out.println("Interrupted");
                return;
            }
            System.out.println("Finished");
        }

        public static void main(String[] args) {
             // spot the difference ->
             ExecutorService executorService = Executors.newWorkStealingPool(4);
             Future future = executorService.submit(new MyClass());
             Thread.sleep(100);
             future.cancel(true);
        }
    }
  

下面的例子可以完美地工作：

public static class MyClass implements Runnable {

        @Override
        public void run() {
            try {
                Thread.sleep(2000);
            } catch (InterruptedException ex) {
                System.out.println("Interrupted");
                return;
            }
            System.out.println("Finished");
        }

        public static void main(String[] args) {
             ExecutorService executorService = Executors.newSingleThreadExecutor();
             Future future = executorService.submit(new MyClass());
             Thread.sleep(100);
             future.cancel(true);
        }
    }
  

编辑：添加返回和更新的睡眠时间和另一个示例。

这比我最初想象的要简单。问题是work-stealing-pool在内部使用ForkJoinPool，而ForkJoinTask不支持cancel(true)，因此在任务启动后不可能取消任务。

请参阅 javadoc 文档（http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ForkJoinTask.html http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ForkJoinTask.html):

   mayInterruptIfRunning - this value has no effect in the default implementation 
   because interrupts are not used to control cancellation.