multiprocessing problem on macOSX arm architecture

[j-l-s]

Then running the Tuto-GUDHI-ConfRegions-PersDiag-datapoints.ipynb notebook on macOSX/M1, the following error occurs in all childs:
AttributeError: Can't get attribute 'hauss_dist' on <module 'persistence_statistics'

This is due to a known problem of the multiprocessing package.
https://stackoverflow.com/questions/69493104/multiprocessing-example-giving-attributeerror-on-mac

Workaround:

• use context "fork" instead of "spawn"

context = get_context("fork")
with context.Pool(ncores) as p:
    dist_vec = p.map(hauss_dist,[m]*B)

(it may not work if not in a if __name__ == "__main__": block

• use another multi-threading library

[mglisse]

Thank you for the report. Since inside Gudhi we mostly use joblib, I think the easiest from a maintenance point of view would be to switch this notebook to use joblib as well.