[Numpy-discussion] Numpy wheels, openBLAS and threading

Max Linke max_linke at gmx.de
Thu Sep 28 09:37:07 EDT 2017

os.environ can be used to change environment variables from within


I do not know when openBLAS is reading the environment variables though.
Changing a value while your python process is running might be to late.

Jean-Christophe Houde writes:

> Hi all,
> not sure if this is the best place to ask for this. If not, please advise
> on the correct place.
> Since the numpy wheels internally use openBLAS, operations can be
> implicitly multithreaded directly by openBLAS.
> This, of course, can clash with multithreading or parallel processing. The
> recommended practice in this case is to set
> in the environment. However, I would like to be able to adjust this
> directly in my python code.
> Is there a way to control this directly through Python, whether through
> numpy or not?
> Thanks for your time!

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