CountDownLatch闭锁

闭锁，多线程计数器；

1. 创建 闭锁对象CountDownLatch countDownLatch = new CountDownLatch(10); 倒数10此
2. 每次执行线程任务countDownLatch.countDown(); -1
3. 等待 计数器完成倒数操作countDownLatch.await();, 才往下继续执行

import java.util.concurrent.CountDownLatch;

public class CountDownLatchDemo {

    public static void main(String[] args) {

        CountDownLatch countDownLatch = new CountDownLatch(10); // 1. 闭锁相当于一个计数器 // 10
        MyRunnable myRunnable = new MyRunnable(countDownLatch);
        long start = System.currentTimeMillis();

        for (int i = 0; i <10; i++) {
            new Thread(myRunnable).start();
        }

        // 3. 等待 计数器完成倒数操作, 才往下执行
        try { countDownLatch.await(); } catch (InterruptedException e) { e.printStackTrace(); }
        long end = System.currentTimeMillis();

        Console.log("=====多线程,执行完成时间====>{}",end-start);
    }
}


class MyRunnable  implements Runnable {
    private CountDownLatch latch;

    public MyRunnable(CountDownLatch latch) {
        this.latch = latch;
    }

    @Override
    public void run() {
        synchronized (MyRunnable.class) {

            try {
                for (int i =0; i<10000; i++){
                    Console.log(i);
                }
            } finally {
                // 2. 每次执行线程任务, 计数器-1
                latch.countDown();
            }
        }

    }
}