java - 当我尝试倒计时时同步被阻塞

Question

我关注了the advice I found in this post使用 CountDownLatch 我遇到了问题。我编写了这个测试并运行它，当我尝试同步锁定时，我的线程创建了 block 。

  private CountDownLatch lock = new CountDownLatch(1);

  @Test
  public void testBlock() {
    Runnable r = new Runnable() {
      @Override
      public void run() {
        try
        {
          synchronized(this) {
            this.wait(50);
          }
        }
        catch (InterruptedException e)
        {
          e.printStackTrace();
          throw (new RuntimeException(e));
        }
        releaseLock();
      }
    };

    Thread t = new Thread(r);
    t.setDaemon(true);
    t.start();

    waitOnCallback();
  }

  private void releaseLock() {
    synchronized(lock) { // Thread t blocks here
      lock.countDown();
    }
  }

  private void waitOnCallback() {
    synchronized(lock) {
      try
      {
        lock.await();
      }
      catch (InterruptedException e)
      {
        throw new RuntimeException(e);
      }
    }
  }

为什么这不起作用？

Answer 1

CountDownLatch 不是需要同步的对象(即删除 synchronized(lock) block )。所有线程安全都在对象本身内部处理。