Using python multiprocess outside the main script

Question

According to the docs of python's multiprocess the spawning of process needs to be inside of the if __name__ == '__main__': clause to prevent spawning infinite processes.

My question, is it possible to use multiprocess inside of an import?

Something along those lines of this: let's say I have this py which is the main executed file:

import foo

def main():
    foo.run_multiprocess()

if __name__ =='__main__':
    main()

and the foo.py file which is imported:

def run_multiprocess(number_to_check):
    if number_to_check == 5:
        print(number_to_check)

if __name__ == '__main__':
    list_to_check = {1,2,3,4,5,6,7}
    pool = Pool(processes=4)             
    pool.map(process_image, list_to_check) 

Obviusly this won't work because the code inside the if statment in foo.py won't run. Is there a way to make it work though?

Answer 1

Multiprocessing doesn't have to run within the __main__ block, __main__ block is only used if the file is ran via python filename.py.

So if you did:

m1.py:

from multiprocessing import Pool    
def f(x):
    return x^2

def f2():
    p = Pool(5)
    p.map(f, [1,2,3,4,5])

m2.py:

from m1 import f2

if __name__ == '__main__':
    f2() # this would run multiprocessing code

and then call python m2.py, your code would run correctly, with mp.