Way to use Multiple queue to communicate between two python scripts

Question

I have two python scripts viz script_1.py and script_2.py This are small snippets of a project I am working. This is what I intend to do

script_2 will start first, it will calculate the lenght of a list and will pass this count to script_1
In script_1, it gets this count this will then generate a second list and if the newcount is greater than received count, it will pass a message stop to the script_2
Finally, in script_2 there is a data function which has an infinite loop. Under that loop it will receive this message and if message is stop, it will break the loop and start over gain.

i have used Queue method of multiprocessing to achieve this. Below are the codes that i have, when i run them i do not get any results.

script_2.py

from multiprocessing import Process,Queue,Pipe
from script_1 import scan_fn

def data_fn(q2):
    msg = q2.get()
    print(msg)
    if(msg == 'stop'):  #this will be inside an infinite loop
        print('msg received, end the loop')

if __name__ == 'main':
    q1 = Queue()
    q2 = Queue()

    initial_list = [1,2,3,4,5,6,7,8]
    initalnumber = len(initial_list)
    q1.put(initalnumber)

    iscanprocess = Process(target=scan_fn,args=(q1,q2))
    rdataprocess = Process(target=data_fn,args=q2)

    iscanprocess.start()
    rdataprocess.start()

script_1.py

import multiprocessing
from multiprocessing import Pipe,Process,Queue

def scan_fn(q1,q2):
    ninitialdevice = q1.get()
    while True:
        new_list = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]
        newdevices = len(new_list)
        if (newdevices > ninitialdevice):
            q2.put('stop')

Please tell what is the correct way or what changes are needed.

Vivek Kumar Singh · Accepted Answer · 2021-03-03 17:27:30Z

1

Change script_2.py to the following code:

from multiprocessing import Process,Queue,Pipe
from script_1 import scan_fn

def data_fn(q2):
    msg = q2.get()
    print(msg)
    if(msg == 'stop'):  #this will be inside an infinite loop
        print('msg received, end the loop')

if __name__ == '__main__':
    q1 = Queue()
    q2 = Queue()

    initial_list = [1,2,3,4,5,6,7,8]
    initalnumber = len(initial_list)
    q1.put(initalnumber)

    iscanprocess = Process(target=scan_fn,args=(q1,q2))
    rdataprocess = Process(target=data_fn,args=(q2,))

    iscanprocess.start()
    rdataprocess.start()

answered Mar 3, 2021 at 17:27

Vivek Kumar Singh

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