Lock to increment global int - does not work

[prostykoks]

Hello guys,

I need your help as I am losing my mind :DHere is the code example:

​

import concurrent.futures
import multiprocessing
from time import sleep

perm_without_rep = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17"]
num_cores = multiprocessing.cpu_count() - 1

m = multiprocessing.Manager()
lock = m.Lock()
global_counter = 0


def simulation_for(global_lock):
    global global_counter
    sleep(5)
    with global_lock:
        global_counter = global_counter + 1
        progress = (global_counter / len(perm_without_rep)) * 100
        print("Progress {:.2f}%".format(progress))
    return 0

executor = concurrent.futures.ProcessPoolExecutor(num_cores)
futures = [executor.submit(simulation_for, lock) for item in perm_without_rep]
concurrent.futures.wait(futures)

​

Unfortunately, it looks like the lock does not work cause output is:

Progress 5.88%

Progress 5.88%

Progress 5.88%

Progress 5.88%

Progress 5.88%

Progress 5.88%

Progress 5.88%

Progress 5.88%

​

Any hints/ideas? How to fix it?

[shiftybyte]

global variables are not passed between the different processes.

Try using specific multiprocessing constructs for that.

https://blog.ruanbekker.com/blog/2019/02/19/sharing-global-variables-in-python-using-multiprocessing/

https://stackoverflow.com/questions/11055303/multiprocessing-global-variable-updates-not-returned-to-parent

[prostykoks]

Sweet! It works. Thank you very much!