java - 抛出 InterruptedException 时不会清除线程中断状态

Question

谁能解释为什么这个程序会打印多个“中断”语句。

根据 Thread.sleep javadoc

InterruptedException - if any thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown.

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class Test {

    public static void main(String[] args) throws Exception {

        for (int z = 0; z < 100; z++) {

            ExecutorService executor1 = Executors.newSingleThreadExecutor();

            executor1.execute(new Runnable() {

                @Override
                public void run() {

                    ExecutorService executor2 = Executors.newFixedThreadPool(10);

                    for (int i = 0; i < 10; i++) {

                        executor2.execute(new Runnable() {
                            @Override
                            public void run() {
                                try {
                                    Thread.sleep(1000 * 100);
                                } catch (InterruptedException e) {
                                    if (Thread.currentThread().isInterrupted()) {
                                        System.out.println("interrupted");
                                    }
                                }
                            }
                        });
                    }

                    executor2.shutdownNow();
                    try {
                        executor2.awaitTermination(5, TimeUnit.SECONDS);
                    } catch (InterruptedException e) {
                    }
                }
            });

            executor1.shutdown();

            try {
                executor1.awaitTermination(10, TimeUnit.SECONDS);
            } catch (InterruptedException e) {
            }
        }
    }
}

output - screenshot

Answer 1

来自doc

If this thread is blocked in an invocation of the wait(), wait(long), or wait(long, int) methods of the Object class, or of the join(), join(long), join(long, int), sleep(long), or sleep(long, int), methods of this class, then its interrupt status will be cleared and it will receive an InterruptedException.

当您在 Thread.sleep(1000 * 100) 期间关闭执行程序服务并抛出 InterruptedException 时，状态将被清除。

但是ThreadPoolExecutor通过t.interrupt()重新设置了状态，所以你仍然可以得到状态。

这里是重置状态的一段代码:

    for (Worker w : workers) {
        Thread t = w.thread;
        if (!t.isInterrupted() && w.tryLock()) {
            try {
                t.interrupt();
            } catch (SecurityException ignore) {
            } finally {
                w.unlock();
            }
        }
        if (onlyOne)
            break;
    }