Trick for using multiprocessing with nested functions and lambda expressions

nested.py

import concurrent.futures
import multiprocessing
import sys
import uuid

def globalize(func):
  def result(*args, **kwargs):
    return func(*args, **kwargs)
  result.__name__ = result.__qualname__ = uuid.uuid4().hex
  setattr(sys.modules[result.__module__], result.__name__, result)
  return result

def main():
  @globalize
  def func1(x):
    return x

  func2 = globalize(lambda x: x)

  with multiprocessing.Pool() as pool:
    print(pool.map(func1, range(10)))
    print(pool.map(func2, range(10)))

  with concurrent.futures.ThreadPoolExecutor() as executor:
    print(list(executor.map(func1, range(10))))
    print(list(executor.map(func2, range(10))))

if __name__ == '__main__':
  main()

@EdwinChan Thank you.