java - 执行服务 shutdownNow ，它是如何工作的

Question

根据方法 shutdownNow (ExecutorService) 的文档

There are no guarantees beyond best-effort attempts to stop
      processing actively executing tasks.  For example, typical
      implementations will cancel via {@link Thread#interrupt}, so any
      task that fails to respond to interrupts may never terminate

我有以下代码:

public static void main(String[] args) throws InterruptedException {
        ExecutorService service = Executors.newSingleThreadExecutor(r -> {
            final Thread thread = new Thread(r);
            thread.setDaemon(false);
            return thread;
        });
        service.submit(() -> {
            while (true) {
                Thread.sleep(1000);
                System.out.println("Done: " + Thread.currentThread().isInterrupted());
            }
        });
        Thread.sleep(3000);
        service.shutdownNow();
    }

这是输出:

Done: false
Done: false

两个循环后停止执行。shutdownNow 如何中断我的工作，我只有无限循环，没有检查 Thread.currentThread.isInterrupted();

在我看来，shutdownNow只调用工作线程的中断方法

Answer 1

Thread.sleep() 检查 .isInterrupted() 并在被中断时抛出 InterruptedException。您的 lambda 隐式地 throws InterruptedException，因此当执行程序关闭时它永远不会到达您的 System.out.println。您可以浏览source for ThreadPoolExecutor看看这是怎么发生的。