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 dictionary, but I keep getting
TypeError: fp() got multiple values for argument 'what'
Here's the code:
from multiprocessing import Pool, 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'} p = Process(target=fp, args=('bob'+str(i)), kwargs={'what':'yes'}) p.start() print("Start done") p.join() print("Join done") print (numList)
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 Pool, 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)
