title: python resource limits
body: <p>Is there some limit for usage of subprocess.Popen..? I observed that it fails continuously at 1017`th execution of external command. </p>
  
  <p>usage:
  <code>subprocess.Popen (cmd, shell=True, stdout=file_hndl, stderr=file_hndl)</code></p>
  
  <p>Expecting the error and output to be redirected to file with file object <code>file_hndl</code></p>