Python Multiprocessing - How to pass kwargs to function?

Question

How do I pass a dictionary to a function with Python\'s Multiprocessing? The Documentation: https://docs.python.org/3.4/library/multiprocessing.html#reference says to pass a

Answer 1

When I ran your code, I got a different error:

TypeError: fp() takes at most 3 arguments (5 given)

I debugged by printing args and kwargs and changing the method to fp(*args, **kwargs) and noticed that "bob_" was being passed in as an array of letters. It seems that the parentheses used for args were operational and not actually giving you a tuple. Changing it to the list, then also passing in numList as a keyword argument, made the code work for me.

from multiprocessing import Process, Manager

def fp(name, numList=None, what='no'):
    print ('hello %s %s' % (name, what))
    numList.append(name+'44')

if __name__ == '__main__':

    manager = Manager()

    numList = manager.list()
    for i in range(10):
        keywords = {'what': 'yes', 'numList': numList}
        p = Process(target=fp, args=['bob'+str(i)], kwargs=keywords)
        p.start()
        print("Start done")
        p.join()
        print("Join done")
    print (numList)