Unit testing multiprocessing code on Windows

philip at semanchuk.com philip at semanchuk.com
Fri Feb 18 02:22:37 CET 2011


Quoting Matt Chaput <matt at whoosh.ca>:

> Does anyone know the "right" way to write a unit test for code that  
> uses multiprocessing on Windows?
>
> The problem is that with both "python setup.py tests" and  
> "nosetests", when they get to testing any code that starts Processes  
> they spawn multiple copies of the testing suite (i.e. the new  
> processes start running tests as if they were started with "python  
> setup.py tests"/"nosetests"). The test runner in PyDev works properly.
>
> Maybe multiprocessing is starting new Windows processes by copying  
> the command line of the current process? But if the command line is  
> "nosetests", it's a one way ticket to an infinite explosion of  
> processes.



Hi Matt,
I assume you're aware of this documentation, especially the item  
entitled "Safe importing of main module"?

http://docs.python.org/release/2.6.6/library/multiprocessing.html#windows


HTH
P




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