title: Alternate to Busy-Wait
body: <p>In my application, Jobs will be submitted dynamically, I need to keep track of submitted job's completion. While I shutdown my application, I want to wait till all the submitted jobs completed. For this I maintain a list of submitted job ids. As soon as process completion notification is raised, I remove the id from the list. When shutdown is called, I am waiting till the list becomes empty.</p>
  
  <pre><code>while (!ids.isEmpty());
  </code></pre>
  
  <p>Is there a better way to this busy wait. </p>