using print() with multiprocessing and pythonw

William Ray Wing wrw at
Tue Nov 12 21:19:25 CET 2013

On Nov 12, 2013, at 2:12 PM, Isaac Gerg <isaac.gerg at> wrote:

> I launch my program with pythonw and begin it with the code below so that all my print()'s go to the log file specified. 
> if sys.executable.find('pythonw') >=0:
>        # Redirect all console output to file.
>        sys.stdout = open("pythonw - stdout stderr.log",'w')
>        sys.stderr = sys.stdout
> During the course of my program, I call multiprocessing.Process() and launch a function several times.  That function has print()'s inside (which are from warnings being printed by python).  This printing causes the multiprocess to crash.  How can I fix my code so that the print()'s are supressed. I would hate to do a warnings.filterwarnings('ignore') because when I unit test those functions, the warnings dont appear.
> Thanks in advance,
> Isaac
> -- 

This may be inelegant, but it solved a similar problem for me.  Replace the print statements with statements and have each invocation of the function dump to a unique log file (with a name based on the function's input).  At least in my case, multiprocessing seemed to get its feet tangled (crash) when different subprocesses tried to print to the same output file at the same time.


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