Java多线程使用 sleep 和中断

Question

class Useless {
    public static boolean b = true;

    public synchronized void u1() {
        try {
            while (b == true)
                wait();
        } catch (InterruptedException i) {
        }
    }

    public synchronized void u2() {
        if (b == true) {
            b = false;
        }
        notify();
    }
}

public class SleepMessages extends Thread {

private Useless u;

    public SleepMessages(Useless u) {
        this.u = u;
    }

    public void run() {
        String importantInfo[] = { "Mares eat oats", "Does eat oats" };
        for (int i = 0; i < importantInfo.length; i++) {
            u.u1();
            System.out.println(importantInfo[i] + " - " + getName());
            try {
                sleep(2000);
            } catch (InterruptedException e) {
            }
        }
    }

    public static void main(String args[]) throws InterruptedException {
        Useless u = new Useless();
        Thread t1 = new SleepMessages(u);
        t1.setName("t1");
        Thread t2 = new SleepMessages(u);
        t2.setName("t2");
        t1.start();
        t2.start();
        sleep(2000);
        System.out.println("Here they go!...");
        t1.interrupt();
        sleep(1000);
        t2.interrupt();
        u.u2();
        sleep(1000);
        u.u2();
    }
}

这个小程序的输出给出: 他们来了!... 母马吃燕麦 - t1 母马吃燕麦 - t2 吃燕麦吗-t2 吃燕麦吗 - t1

我的问题是为什么线程 t2 是唯一进入 catch(InterruptedException e) 的线程，为什么结果不是这样的:

他们来了!... 母马吃燕麦 - t1 母马吃燕麦 - t2 吃燕麦吗 - t1 吃燕麦吗 - t2

Answer 1

My question is why does the thread t2 is the only one that enters the catch(InterruptedException e),

在我看来，t1.interrupt() 正在中断 run() 方法中的 sleep 。一旦丢弃 InterruptedException，就无法知道线程之前是否被中断过。

why isn't the result something like this: Here they go!... Mares eat oats - t1 Mares eat oats - t2 Does eat oats - t1 Does eat oats - t2

Java 使用偏向锁定。这意味着最后一个获取锁的线程更有可能首先获取相同的锁。