Java中的CountDownLatch简单理解

public class Test {
    public static void main(String[] args) throws InterruptedException {
        //当前执行的线程数量
        Integer poolNum = 10;
        long start = System.currentTimeMillis();
        //初始化线程运行的数量
        CountDownLatch countDownLatch = new CountDownLatch(poolNum);
        Map<Integer,Integer> map = new HashMap<>();
        for (int i = 1; i <= poolNum; i++) {
            //耗时
            Integer time = i*1000;
            ThreadPoolUtils.execute(()->{
                try {
                    //假设逻辑执行的耗时
                    Thread.sleep(time);
                    map.put(time,time);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }finally {
                    countDownLatch.countDown();
                }
            });
        }
        countDownLatch.await();
        System.out.println("总耗时:"+(System.currentTimeMillis()-start));
        for (Integer key: map.keySet()){
            //打印出来的key值是没有顺序的，因为竞争的CPU资源不一样
            System.out.println("map的key为:"+key+" map的值为:"+ map.get(key));
        }
    }
}