并发编程之waitSet

public class WaitSetDemo {

    private static final Object LOCK = new Object();

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

        IntStream.rangeClosed(0, 10).forEach(i -> {
            new Thread(String.valueOf(i)) {
                @Override
                public void run() {
                    synchronized (LOCK) {
                        try {
                            System.out.println(" ThreadName-> " + Thread.currentThread().getName() + " enter waitSet ");
                            LOCK.wait();
                            System.out.println(" ThreadName-> " + Thread.currentThread().getName() + " out waitSet ");
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }

                    }
                }
            }.start();
        });

        Thread.sleep(10000);

        IntStream.rangeClosed(0, 10).forEach(i -> {
            synchronized (LOCK) {
                LOCK.notify();
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

执行结果

 ThreadName-> 0 enter waitSet 
 ThreadName-> 1 enter waitSet 
 ThreadName-> 2 enter waitSet 
 ThreadName-> 3 enter waitSet 
 ThreadName-> 4 enter waitSet 
 ThreadName-> 5 enter waitSet 
 ThreadName-> 6 enter waitSet 
 ThreadName-> 7 enter waitSet 
 ThreadName-> 8 enter waitSet 
 ThreadName-> 9 enter waitSet 
 ThreadName-> 10 enter waitSet 
 ThreadName-> 0 out waitSet 
 ThreadName-> 1 out waitSet 
 ThreadName-> 4 out waitSet 
 ThreadName-> 3 out waitSet 
 ThreadName-> 2 out waitSet 
 ThreadName-> 6 out waitSet 
 ThreadName-> 5 out waitSet 
 ThreadName-> 7 out waitSet 
 ThreadName-> 9 out waitSet 
 ThreadName-> 8 out waitSet 
 ThreadName-> 10 out waitSet 

结论

1、所有的对象都会有一个wait set，用来存放调用了该对象的wait方法之后进入block状态的线程

2、wait() 调用者是Lock对象，是释放锁的；sleep() 调用者是线程自己，但不释放锁。

3、线程被notify唤醒后，不一定立即执行。

​ 唤醒顺序不是FIFO。

​ 当线程重新获得锁后，也不会从头开始执行，而是从wait处之后的代码开始继续执行（执行地址恢复）。