title: What is the relationship between workers, worker instances, and executors?
body: <p>In <strong>Spark Standalone mode</strong>, there are master and worker nodes.</p>
  <p>Here are few questions:</p>
  <ol>
  <li>Does 2 worker instance mean one worker node with 2 worker processes?</li>
  <li>Does every worker instance hold an executor for specific application (which manages storage, task) or one worker node holds one executor?</li>
  <li>Is there a flow chart explaining how spark works on runtime, such as word count?</li>
  </ol>