Unprotected use of multiprocessing.cpu_count()

[henryiii]

iminuit/cmake.py

Line 40 in 2b47d07

njobs = self.parallel if self.parallel else multiprocessing.cpu_count()

This could throw and is currently unprotected. See https://docs.python.org/3.5/library/multiprocessing.html#multiprocessing.cpu_count . Instead, maybe use os.cpu_count(), new in 3.4+: https://docs.python.org/3.5/library/os.html#os.cpu_count which returns None instead if undeterminable.

Suggestion:

njobs = self.parallel or multiprocessing.cpu_count() or 1

[HDembinski]

Thank you that is a good suggestion, will do.

[henryiii]

Looks good! Have I mentioned I love Python 3? :)

[HDembinski]

Yes, it is great, and now that we don't have to support 3.5 anymore, I can also use f-strings in libraries...

[henryiii]

I am curious to see pyupgrade on iMinuit, see scikit-hep/pyhf#1164.

Good, 3.6+ is great. :)