• CountDownLatch : 是闭锁,通过一个计数来保证线程是否一直阻塞

CountDownLatch也是一个java.util.concurrent包中的类，可以设置一个初始数值，在数值大于0之前让调用await()方法的线程堵塞住，数值为0是则会放开所有阻塞住的线程。底层基于AQS实现

CountDownLatch 是一个同步工具，它可以让一个或多个线程等待其他线程完成操作后再继续执行。其中使用 CountDownLatch 等待多个线程完成后再执行主线程：

代码示例：

import java.util.concurrent.CountDownLatch;
 
public class CountDownLatchExample {
    public void performTask() throws InterruptedException {
        int numThreads = 3;
        CountDownLatch latch = new CountDownLatch(numThreads);
 
        for (int i = 0; i < numThreads; i++) {
            Thread thread = new WorkerThread(latch);
            thread.start();
        }
 
        latch.await(); // 等待所有线程完成
        System.out.println("All worker threads have completed.");
    }
 
    private static class WorkerThread extends Thread {
        private CountDownLatch latch;
 
        public WorkerThread(CountDownLatch latch) {
            this.latch = latch;
        }
 
        public void run() {
            // 执行任务
            latch.countDown(); // 任务完成后减少计数
        }
    }
}

https://blog.csdn.net/javanewber/article/details/132189657

https://cloud.tencent.com/developer/article/1786286

CountDownLatch和ReentrantLock在是实现上的区别

CountDownLatch底层原理？

如果不用CountDownLatch，还可以用什么方案？