title: PipeMapRed.waitOutputThreads(): subprocess failed with code 1
body: <p>I am getting below error when i ran a map reduce job. My input is a sequencefile of 26MB.</p>
  
  <pre><code>16/02/28 17:51:22 INFO mapreduce.Job: Task Id : attempt_1456551797554_0004_m_000000_0, Status : FAILED
  Error: java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 1
          at org.apache.hadoop.streaming.PipeMapRed.waitOutputThreads(PipeMapRed.java:322)
          at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:535)
          at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:130)
          at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:61)
          at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:34)
          at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:450)
          at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
          at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:163)
          at java.security.AccessController.doPrivileged(Native Method)
          at javax.security.auth.Subject.doAs(Subject.java:415)
          at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)       
          at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158)
  </code></pre>
  
  <p>My stderr output is:</p>
  
  <pre><code>log4j:WARN No appenders could be found for logger (org.apache.hadoop.ipc.Server).
  log4j:WARN Please initialize the log4j system properly.
  log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
  </code></pre>
  
  <p>Note: The mapper ran perfectly fine when i executed it locally but gave the error when i ran the job in hadoop. The only difference is that in locally the file i used was at my home directory and in hadoop job i used the same file but at hdfs location.</p>
  
  <p>I have mentioned '#!/usr/bin/env python' at the top of my mapper.py</p>