do cleanup work when sub-process exit

multiprocess_with_finalizer.py

import multiprocessing as mp
from multiprocessing.util import Finalize
import os
import time

def finalizer():
    time.sleep(0.2) # some time consuming work
    print('do cleanup work: {}'.format(os.getpid()))

def worker(_):
    print('do some work: {}'.format(os.getpid()))

def initializer():
    # ref: https://github.com/python/cpython/blob/master/Lib/multiprocessing/util.py#L147
    Finalize(None, finalizer, exitpriority=1)

    # atexit module don't work along with multiprocessing module
    # because sub-process exit via os._exit()
    # ref: https://docs.python.org/3/library/atexit.html
    # atexit.register(finalizer)  # don't work

print('main process ID: {}'.format(os.getpid()))
with mp.Pool(4, initializer=initializer) as executor:
    executor.map(worker, range(20))