[BangPypers] Python script hangs after using logging module

Noufal Ibrahim KV noufal at nibrahim.net.in
Tue May 27 07:18:33 CEST 2014

On Tue, May 27 2014, Rahul Gopan wrote:

> #!/usr/local/bin/python2.7
> import commands
> import subprocess
> items = commands.getoutput('COMMAND <branch> <Begin_no> <End_no> | wc -l')
> print items
> -- Works --
> #!/usr/local/bin/python2.7
> import commands
> import subprocess
> import logging
> logging.basicConfig(filename='Log_file.log',filemode='w',format='%(asctime)s
> %(message)s',level=logging.DEBUG)
> items = commands.getoutput('COMMAND <branch> <Begin_no> <End_no> | wc -l')
> print items
> -- Hangs --

A few suggestions. 
1. Consider using subprocess or envoy[1] instead of commands. It's
2. Please specify exactly what you're trying to run rather than the
   placeholder you've put in your script above. My guess is that it's
   waiting for input and holding up the pipeline so that wc is never
3. Try running that command outside to see what the behaviour is. 
4. If the command works, make sure that your script is running in the
   same directory and with the same environment as the one where the
   command works.
5. I'd be inclined to do the `wc` in Python rather than use a pipe. It
   looks okay in this case but usually, involving the shell while trying
   to execute something leads to headaches with quoting, variable expansion
   and other such things that are not worth it. 
6. The basicConfig line will actually create and open the Log_file.log
   file. If you're on a disk that's misbehaving (e.g. a stale NFS
   mount), it might hang. Try creating the file manually outside the
   script to see if that's the issue.


[1]  https://github.com/kennethreitz/envoy


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