BUG: Disable parallel cythonize on Windows (GH 30214)

[Dr-Irv]

• [x ] closes #30214 (Parallelized Build / CI) caused a build failure for me #30356
• tests added / passed
  • N/A
• passes black pandas
  • Didn't run - changes too many files
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

Added test in setup.py to check if nthreads is positive and on Windows.

[WillAyd]

Can you also enable this for Windows CI? Would be curious to see how much time it saves there

[Dr-Irv]

Can you also enable this for Windows CI? Would be curious to see how much time it saves there

@WillAyd If I "enable" it for Windows CI, then all compiles would run sequentially. So that wouldn't save time (assuming the parallel stuff is working now). What am I missing here?

[WillAyd]

I meant should add the “-j N” flag to the build command for Windows in the CI folder. We currently don’t pass anything so Cythonization and compilation are sequential

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On Dec 31, 2019, at 4:04 PM, Irv Lustig ***@***.***> wrote:  Can you also enable this for Windows CI? Would be curious to see how much time it saves there @WillAyd If I "enable" it for Windows CI, then all compiles would run sequentially. So that wouldn't save time (assuming the parallel stuff is working now). What am I missing here? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe.

[Dr-Irv]

I meant should add the “-j N” flag to the build command for Windows in the CI folder. We currently don’t pass anything so Cythonization and compilation are sequential

OK, I put that in the last commit

[topper-123]

I've tried this solution out, and compilation works fine for me.

Would be interesting to try parallizing on Windows when cython/cython#3262 is solved in a new Cython release.

[jreback]

thanks @Dr-Irv