Error using multiprocessing with pyconcrete

[sharadkak]

Hi,

I'm getting a pickle error while using multiprocessing with Pyconcrete. However the code works just fine without pyconcrete.
I am using python 3.8 with docker. To create a docker image I am using the docker file from the repository https://github.com/Falldog/pyconcrete/blob/master/docker/Dockerfile.

The error I am getting is
Traceback (most recent call last): File "main.py", line 17, in <module> File "/usr/lib/python3.8/multiprocessing/process.py", line 121, in start self._popen = self._Popen(self) File "/usr/lib/python3.8/multiprocessing/context.py", line 284, in _Popen return Popen(process_obj) File "/usr/lib/python3.8/multiprocessing/popen_spawn_posix.py", line 32, in __init__ super().__init__(process_obj) File "/usr/lib/python3.8/multiprocessing/popen_fork.py", line 19, in __init__ self._launch(process_obj) File "/usr/lib/python3.8/multiprocessing/popen_spawn_posix.py", line 47, in _launch reduction.dump(process_obj, fp) File "/usr/lib/python3.8/multiprocessing/reduction.py", line 60, in dump ForkingPickler(file, protocol).dump(obj) _pickle.PicklingError: Can't pickle <function task_fn at 0x7f376688b1f0>: attribute lookup task_fn on __main__ failed

I also attach the code below:

import os
import time

def task_fn(l):
    results = []
    for each in l:
        print(each**20)

if __name__ == '__main__':
    print("Main process id ", os.getpid())
    l = [i**2 for i in range(10)]

    ctx = mp.get_context('spawn')
    p = ctx.Process(target= task_fn, args = (l,))
    p.start()
    print(p.name)
    p.join()
    p.close()