[FIXED] Why import numpy create threads?

Issue

mytest.py:

import time
import numpy
time.sleep(1000)
print(1)

Excute it and check threads with:

ps -eaf -T | grep mytest

And 24 lines show up.

But if I remove import numpy, only one line remains.

Solution

Threads are created by math libraries used by numpy, eg. MKL, BLAS, openMP.

See:

https://numpy.org/devdocs/reference/global_state.html

https://github.com/numpy/numpy/issues/11826

Answered By - PaleNeutron