title: hadoop cannot allocate memory java.io.IOException: error=12
body: <p>i am getting the following error on hadoop greenplum</p>
  
  <pre><code>java.lang.Throwable: Child Error
      at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:271)
  Caused by: java.io.IOException: Cannot run program "ln": java.io.IOException: error=12, Cannot allocate memory
      at java.lang.ProcessBuilder.start(ProcessBuilder.java:488)
      at java.lang.Runtime.exec(Runtime.java:610)
      at java.lang.Runtime.exec(Runtime.java:448)
      at java.lang.Runtime.exec(Runtime.java:386)
      at org.apache.hadoop.fs.FileUtil.symLink(FileUtil.java:567)
      at org.apache.hadoop.mapred.TaskLog.createTaskAttemptLogDir(TaskLog.java:109)
      at org.apache.hadoop.mapred.DefaultTaskController.createLogDir(DefaultTaskController.java:71)
      at org.apache.hadoop.mapred.TaskRunner.prepareLogFiles(TaskRunner.java:316)
      at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:228)
  Caused by: java.io.IOException: java.io.IOException: error=12, Cannot allocate memory
      at java.lang.UNIXProcess.&lt;init&gt;(UNIXProcess.java:164)
      at java.lang.ProcessImpl.start(ProcessImpl.java:81)
      at java.lang.ProcessBuilder.start(ProcessBuilder.java:470)
      ... 8 more
  </code></pre>
  
  <p>the server has 7G ram and 1G swap.</p>
  
  <p>heap size is 1024m and mapred.child.opts is set to 512m.</p>
  
  <p>any ideas?</p>