如果Thread.sleep是静态的，那么各个线程如何知道它被置于睡眠状态？ [英] if Thread.sleep is static, how does individual thread knows it is put to sleep?

问题描述

我对 Thread.sleep（）方法感到困惑。 if Thread.sleep（）是一个静态方法，两个线程如何知道哪个线程处于休眠状态。例如，在下面的代码中，我有两个三主题
主， t 和 t1 。我总是打电话给 Thread.sleep（）。不是 t.sleep（）。这是否意味着Thread.sleep（）将当前线程置于睡眠状态？这意味着Thread实例通过调用静态方法自行进入休眠状态。如果t1想要让 t 进入睡眠状态怎么办？这应该不正确吗？

I am a bit confused with Thread.sleep() method. if Thread.sleep() is a static method, how does two threads know which is put to sleep. For example, in the code below, I have two three Threads main, t and t1. I call Thread.sleep() always. Not t.sleep(). Does it mean Thread.sleep() puts the current Thread to sleep? That means a Thread instance puts to sleep by itself by calling the static method. what if t1 wants to put t to sleep. that shouldn't be possible correct?

public class ThreadInterrupt {

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

        System.out.println("Starting.");

        Thread t  = new Thread(new Runnable(){

            @Override
            public void run() {
                Random ran = new Random();

                for (int i = 0; i < 1E8; i++) {

                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        System.out.println("we have been interrupted");
                        e.printStackTrace();
                    }
        });

        Thread t2 = new Thread(new Runnable() {
                 public void run() {
                         //some stuff
                 }
        });    
        t.start();
        t2.start();

        Thread.sleep(500);
        t.interrupt();
        t.join();

        System.out.println("Finished.");
    }

}

推荐答案

是否意味着Thread.sleep（）将当前线程置于休眠状态？

Does it mean Thread.sleep() puts the current Thread to sleep?

是。只有当前线程可以做到这一点。

Yes. Only the current thread can do that.

如果t1想让t进入睡眠状态怎么办？那不应该是正确的吗？

What if t1 wants to put t to sleep. that shouldn't be possible correct?

对。您可以设置一个 volatile boolean 标志，该标志将导致另一个线程调用 Thread.sleep（...）但另一个线程不能导致线程休眠。

Right. You can set a volatile boolean flag that will cause another thread to call Thread.sleep(...) but another thread can't cause a thread to sleep.

 volatile boolean shouldSleep = false;
 ...
 // check this flag that might be set by another thread to see if I should sleep
 if (shouldSleep) {
     Thread.sleep(...);
 }

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