title: shutdown and awaitTermination which first call have any difference?
body: <p>What is the difference between</p>
  
  <pre><code>ExecutorService eService = Executors.newFixedThreadPool(2);
  eService.execute(new TestThread6());
  eService.execute(new TestThread6());
  eService.execute(new TestThread6());
  eService.awaitTermination(1, TimeUnit.NANOSECONDS);
  eService.shutdown();
  </code></pre>
  
  <p>and</p>
  
  <pre><code>eService.shutdown();
  eService.awaitTermination(1, TimeUnit.NANOSECONDS);
  </code></pre>
  
  <p>I don't really understand <code>shutdown()</code>. This method does not wait for previously submitted tasks to complete execution. Does it mean <code>shutdown()</code> may terminate the tasks which have been submitted, but not completed? I tried some examples, they do not prove it, please give me an example. </p>