java - 主线程等待两个并行子线程java

Question

首先我想做的是:

在主线程执行期间，我想暂停主线程并启动两个并行线程。一旦这两个并行线程终止，我想再次从主线程开始。

我尝试过:

    ...
    ...
    main thread is executing
    ...
    ...
CyclicBarrier barrier = new CyclicBarrier(2);
Thread child1 = new Thread(new ThreadBuilderTask(barrier,0));
Thread child2 = new Thread(new ThreadBuilderTask(barrier,1));

child1.start();
child2.start(); 

/* Now i'm expecting that child1 and child2 are running in parallel calling their fooFunction */

child1.join();
child2.join(); 
/*Now i'm expecting that main thread will wait for child1and also for child2 (that are running in parallel).*/

... main thread starts again after both child1 and child2 finished (reached the await of the barrier) 
... (break point set here, never reached)
...

线程构建器自定义类

public class ThreadBuilderTask implements Runnable{
    private CyclicBarrier barrier;
    private int index;
    ...setters and getters..

    @Override
    public void run() {
        fooFunction(this.getIndex());
        try {
            this.getBarrier().await();
        } catch (InterruptedException | BrokenBarrierException e) {
            return;
        }
    }

    public ThreadBuilderTask(CyclicBarrier barrier,int index){
      this.barrier = barrier;
      this.index = index;
    }

    public fooFunction(int index){
        //Something taking some seconds to execute
    }

尚不清楚这里发生了什么，但它肯定不起作用。一旦我调用 join 一切都会停止并且主线程永远不会重新启动。 (我在连接后放置了一个断点，以查看主线程何时重新启动)。

也许这些概念有些困惑，而且我不确定是否需要同时使用屏障和连接，或者仅使用其中一种技术。

谢谢

戴维德

Answer 1

正如评论中提到的，我还建议使用CompletableFuture。您所描述的要求的一个非常基本的示例可能如下所示:

final Runnable runnable1 = ...;
final Runnable runnable2 = ...;

CompletableFuture<Void> future1 = CompletableFuture.runAsync(runnable1);
CompletableFuture<Void> future2 = CompletableFuture.runAsync(runnable2);

CompletableFuture.allOf(future1, future2).get(); // waits for both runnables to finish

您可能想为此示例添加更多/一些异常处理。但它应该能让您了解这是如何运作的。