一个关于ExecutorService shutdownNow时很奇怪的现象

我们知道很多类库中的阻塞方法在抛出InterruptedException后会清除线程的中断状态(例如 sleep、 阻塞队列的take),但是今天却发现了一个特别奇怪的现象,先给出代码:

    public static void main(String[] args) throws InterruptedException {
        ExecutorService executor = Executors.newSingleThreadExecutor();
        executor.execute(new Runnable() {
            @Override
            public void run() {
                try {
                    TimeUnit.SECONDS.sleep(10);
                } catch (InterruptedException e) {
                    System.out.println("first interrupted!!!");
                }
                
                System.out.println(Thread.currentThread().isInterrupted());
                
                try {
                    TimeUnit.SECONDS.sleep(1);
                } catch (InterruptedException e) {
                    System.out.println("second interrupted!!!");
                }
            }
        });
        
        executor.shutdownNow();
    }

 如果按照我的理解,调用shutdownNow后会给线程池中的工作者线程发出中断请求,并在第一个睡眠的地方抛出 InterruptedException ,但是在抛出异常后这种中断状态就应该被清除了,所以第二次睡眠不应该失败,但是结果却是失败的,本来以为是系统的原因,可是在linux下测试也是如此。

更令人不解的是如果我把第二次睡眠换成其他的阻塞方法(queue.take)那么就不会抛出异常,而是正常阻塞。 

    public static void main(String[] args) throws InterruptedException {
        ExecutorService executor = Executors.newSingleThreadExecutor();
        final BlockingQueue<String> queue = new LinkedBlockingQueue<>();
        executor.execute(new Runnable() {
            @Override
            public void run() {
                try {
                    TimeUnit.SECONDS.sleep(10);
                } catch (InterruptedException e) {
                    System.out.println("first interrupted!!!");
                }
                
                System.out.println(Thread.currentThread().isInterrupted());
                
                try {
                    queue.take();
                } catch (InterruptedException e) {
                    System.out.println("second interrupted!!!");
                }
            }
        });
        
        executor.shutdownNow();
    }

 还有更让人受不了的,如果我们在任务最开始随便写点什么,就会按照我们期待的执行了(心中一万只草泥马呀)

    public static void main(String[] args) throws InterruptedException {
        ExecutorService executor = Executors.newSingleThreadExecutor();
        executor.execute(new Runnable() {
            @Override
            public void run() {
                System.out.println("xxxx");
                try {
                    TimeUnit.SECONDS.sleep(10);
                } catch (InterruptedException e) {
                    System.out.println("first interrupted!!!");
                }
                
                System.out.println(Thread.currentThread().isInterrupted());
                
                try {
                    TimeUnit.SECONDS.sleep(2);
                } catch (InterruptedException e) {
                    System.out.println("second interrupted!!!");
                }
            }
        });
        
        executor.shutdownNow();
    }

 

以后有机会再研究吧,可能还是知识不够吧!!!!

 

posted @ 2017-06-26 11:17  zh1164  阅读(2199)  评论(3编辑  收藏  举报