Python Multiprocessing error: AttributeError: module '__main__' has no attribute '__spec__'

Question

I'm using Python 3.6 and am trying to follow along with the very first example at the website below (full code also below) and am getting the below error: https://docs.python.org/3.6/library/multiprocessing.html

Error message: AttributeError: module '__main__' has no attribute '__spec__'

Full example code:

from multiprocessing import Pool

def f(x):
    return x*x

if __name__ == '__main__':
    with Pool(5) as p:
        print(p.map(f, [1, 2, 3]))

I tried Googling it and searching Stack Overflow but I've only found one other case of this error and it did not have an answer.

Answer 1

The problem is not with the code / Python 3.6, it is with Spyder.

After some investigation I found that the code runs fine when executed in an external system terminal but not when run in Spyder's IPython console.

I was able to dump the contents of spec and assign them to a variable that was included inside main to allow this code to function within the IPython console.

from multiprocessing import Pool

def f(x):
    return x*x

if __name__ == '__main__':
    __spec__ = "ModuleSpec(name='builtins', loader=<class '_frozen_importlib.BuiltinImporter'>)"
    with Pool(5) as p:
       print (p.map(f, [1, 2, 3]))