title: Java: is CountDownLatch threadsafe
body: <p>In the <a href="https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CountDownLatch.html" rel="noreferrer">docs</a> for <code>CountDownLatch</code> I see something like:</p>
  
  <pre>
  public void run() {
        try {
          startSignal.await();
          doWork();
          doneSignal.countDown();
        } catch (InterruptedException ex) {} // return;
  }
  </pre>
  
  <p>Here <code>startSignal</code> and <code>doneSignal</code> are <code>CountDownLatch</code> objects.</p>
  
  <p>The docs don't mention anything about the class being thread-safe or not.</p>