title: Spark - Which instance type is preferred for AWS EMR cluster?
body: <p>I am running some machine learning algorithms on EMR Spark cluster. I am curious about which kind of instance to use so I can get the optimal cost/performance gain?</p>
  
  <p>For the same level of prices, I can choose among:</p>
  
  <pre><code>          vCPU  ECU  Memory(GiB)
  m3.xlarge  4     13     15     
  c4.xlarge  4     16      7.5
  r3.xlarge  4     13     30.5
  </code></pre>
  
  <p>Which kind of instance should be used in EMR Spark cluster?</p>