title: Spark losing println() on stdout
body: <p>I have the following code:</p>
  
  <pre><code>val blueCount = sc.accumulator[Long](0)
  val output = input.map { data =&gt;
    for (value &lt;- data.getValues()) {
      if (record.getEnum() == DataEnum.BLUE) {
        blueCount += 1
        println("Enum = BLUE : " + value.toString()
      }
    }
    data
  }.persist(StorageLevel.MEMORY_ONLY_SER)
  
  output.saveAsTextFile("myOutput")
  </code></pre>
  
  <hr>
  
  <p>Then the blueCount is not zero, but I got no println() output! Am I missing anything here? Thanks!</p>