Parallel processing crashes on Mac

[marfox]

Got a segmentation fault when running the command python -m strephit extraction process_semistructured.

Full stack trace attached.
stacktrace.txt

[marfox]

Also with python -m strephit commons entity_linking.

Full stack trace attached.
stacktrace02.txt

[marfox]

And with python -m strephit commons serialize

Full stack trace attached.
stacktrace03.txt