title: Spark application stops when reading file from s3
body: <p>I have an application which runs on EMR and reads a csv file from s3.
  However, the whole thing seems to stop (I've let it run for about an hour) when I try to read in that file from s3. Nothing happens and nothing is written to the logs any more except that the application is still running. The step in which this application is running does not fail!</p>
  
  <p>I've tried copying the file to the cluster via the flag <code>--files</code> of spark-submit and reading it directly within the application with <code>sc.textFile(filename)</code>.</p>
  
  <p>Is there anything I am missing?</p>