java - 以下 java 程序使用 CountDownLatch 的输出

Question

以下 java prgram 将输出什么 - 是否总是如下所述，或者存在任何可能不同的极端情况 -

预期输出 -
task1 关键部分已完成
task2 关键部分已完成

Java 程序 -

import java.util.concurrent.CountDownLatch;

public class CountDownLatchTest2 {

public static void main(String[] args) {

    CountDownLatch countDownLatch = new CountDownLatch(1);

    RunnableTask1 task1 = new RunnableTask1(countDownLatch);
    RunnableTask2 task2 = new RunnableTask2(countDownLatch);

    Thread t2 = new Thread(task2);
    Thread t1 = new Thread(task1);

    t1.start();
    t2.start();
}

static class RunnableTask1 implements Runnable
{
    private CountDownLatch countDownLatch;

    public RunnableTask1(CountDownLatch countDownLatch) 
    {
        this.countDownLatch = countDownLatch;
    }

    @Override
    public void run()
    {
        System.out.println("task1 critical section completed");
        countDownLatch.countDown();
    }
}

static class RunnableTask2 implements Runnable
{
    private CountDownLatch countDownLatch;

    public RunnableTask2(CountDownLatch countDownLatch) 
    {
        this.countDownLatch = countDownLatch;
    }

    @Override
    public void run()
    {
        try
        {
            countDownLatch.await();
            System.out.println("task2 critical section completed");
        }
        catch (InterruptedException e) 
        {
            System.out.println("task 2 has been interupted");
        }           
    }
}
}

Answer 1

输出将始终是预期的。

System.out.println("task1 critical section completed");发生在之前countDownLatch.countDown();发生在countDownLatch.await();解除阻塞之前。