It's not a problem with PYTHONPATH. If we look in multiprocessing\__init__.py, we see the following:
#
# Copy stuff from default context
#
globals().update((name, getattr(context._default_context, name))
for name in context._default_context.__all__)
__all__ = context._default_context.__all__
Notably there is nothing in the file that looks like Queue, Process, etc.
Now what is this context._default_context? If we look in multiprocessing\context.py, we see
class BaseContext(object):
...
def Queue(self, maxsize=0):
'''Returns a queue object'''
from .queues import Queue
return Queue(maxsize, ctx=self.get_context())
So in reality, Queue is never defined in the module itself, but rather through some dynamic code, it gets set correctly at runtime depending on the user's operating system. This is why Pycharm doesn't know that there are Queue and Process classes in the multiprocessing module.
Maybe you can file a bug report and try to get them to selectively run code to figure out these dynamic names or to make an exception here and put some workaround that tells Pycharm that there are in fact Queue/Process classes, but that seems like it would be low on their priority list. So you'll just have to live with it, probably. (In the same boat here)
