macos - Multiprocessing runtime error freeze_support() in Mac 64 bit

Question

I am trying to learn Threading and Multiprocessing on a MacOS. I am unable to launch the processes though, with python giving the following error message.

Error

RuntimeError: An attempt has been made to start a new process before the current process has finished its bootstrapping phase.

    This probably means that you are not using fork to start your
    child processes and you have forgotten to use the proper idiom
    in the main module:

        if __name__ == '__main__':
            freeze_support()
            ...

    The "freeze_support()" line can be omitted if the program
    is not going to be frozen to produce an executable. 

my code: parallel_processing.py

import multiprocessing
import time

start= time.perf_counter()

def do_something():
    print('sleeping 1 sec....')
    time.sleep(1)
    return('done sleeping...')

# do_something()
p1 = multiprocessing.Process(target = do_something)
p2 = multiprocessing.Process(target = do_something)

p1.start()
p2.start()

finish= time.perf_counter()

print(f'finished in {finish-start} seconds')

Answer 1

等待大神解答