concurrent（五）同步辅助器CountDownLatch & 源码分析

参考文档：

https://blog.csdn.net/zxdfc/article/details/52752803

简介

CountDownLatch是一个同步辅助类。允许一个或多个线程等待其他线程完成操作。内部采用的公平锁和共享锁的机制实现

举个栗子

public class CountDownLatchTest {

    public static void main(String[] args) {
        CountDownLatch cd = new CountDownLatch(2);
        ExecutorService es = Executors.newFixedThreadPool(5);
        for (int i = 0; i < 2; i++) {
            es.execute(new MyThread1(cd));
        }
        System.out.println("wait");
        try {
            cd.await();
            System.out.println("two thread run over");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        es.shutdown();
    }
}

class MyThread1 implements Runnable {
    CountDownLatch latch;
    public MyThread1(CountDownLatch latch) {
        this.latch = latch;
    }
    @Override
    public void run() {
        try {
            Thread.sleep(1000 * 3);
            latch.countDown();
            System.out.println(Thread.currentThread().getName() + " over");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

View Code