Add fork context to multiprocessing

[gkucsko]

on mac with python 3.7+ the default context of multiprocessing changed from fork to spawn, see here: https://stackoverflow.com/questions/64095876/multiprocessing-fork-vs-spawn to allow access to class variables we need to enforce fork context

[lopez86]

on mac with python 3.7+ the default context of multiprocessing changed from fork to spawn, see here: https://stackoverflow.com/questions/64095876/multiprocessing-fork-vs-spawn to allow access to class variables we need to enforce fork context

Is there some workaround for this to work with windows? It looks like the fork context isn't available on windows https://docs.python.org/3/library/multiprocessing.html#contexts-and-start-methods

[gkucsko]

great question... not sure. maybe just accept that batch predict doesn't work on windows? :/