同步阻塞当我尝试CountDown [英] Synchronize Is Blocking When I Try To CountDown

问题描述

我关注了我在此信息中发现的建议使用CountDownLatch和我遇到一个问题。

  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（）; 
} 
}; 
 
线程t =新线程（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）; 
} 
} 
} 
  

？CountDownLatch不是一个需要同步的对象（例如，删除 synchronized（），锁）块）。所有线程安全性都在对象本身内部处理。

I followed the advice I found in this post using CountDownLatch and i'm running into a problem. I wrote up this test and ran it and my thread I created blocks when i try to synchronize on lock.

  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);
      }
    }
  }

Why isn't this working?

解决方案

A CountDownLatch is not an object on which you need to synchronize (i.e. remove the synchronized(lock) blocks). all thread-safety is handled internally to the object itself.

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