Stop process from another process

Question

Hi guys I have two different processes running at the same time. I'm trying to stop the other process which i have named loop_b but I have only managed to stop the current process and the other doesn't stop

from multiprocessing import Process
import time
import sys 


counter=0

def loop_a():
    global counter
    while True:
        print("a")
        time.sleep(1)
        counter+=1
        if counter==10:
            print("I want to stop the loop_b")
            sys.exit()
            #Process(target=loop_b).close()  -> Also i tried this but not worked

def loop_b():
    while True:
        print("b")
        time.sleep(1)

if __name__ == '__main__':
    Process(target=loop_a).start()
    Process(target=loop_b).start()

Answer 1

One possible solution could be using multiprocessing.Event synchronization primitive to signal other process that it should exit, e.g.:

import sys
import time
from multiprocessing import Event, Process


def loop_a(evt):
    counter = 0

    while True:
        print("a")
        time.sleep(1)
        counter += 1
        if counter == 3:
            print("I want to stop the loop_b")
            evt.set()  # <-- set the flag to be True to signal exit
            sys.exit()


def loop_b(evt):
    while not evt.is_set():
        print("b")
        time.sleep(1)


if __name__ == "__main__":
    evt = Event()

    p1 = Process(target=loop_a, args=(evt,)).start()
    p2 = Process(target=loop_b, args=(evt,)).start()

Prints:

a
b
a
b
a
b
I want to stop the loop_b  # <-- and the loob_b ends here too