python threading start/stop

Question

I am trying to implement a start/stop function in my code.

For simplicity lets assume I have two functions:

def setup():
    global start_process
    # setting up some parameters with user inputs
    actual_process()

def actual_process():
    global start_process, continue_process
    start_process = True
    while start_process:

        continue_process = True

        thread_1 = threading.Thread(target=start_stop)
        thread_1.daemon = True 
        thread_1.start()

        # do something infinitely


def start_stop():
    global continue_process, start_process
    while continue_process:
        user_input = input('Press "r" to restart or "s" to stop: ')
        if user_input == 's':
            continue_process = False
            start_process = False
            print('closing program')

        if user_input == 'r':
            continue_process = False
            start_process = False
            print('Restarting')
            setup()

setup()

But when I enter 's' or 'r' the function start_stop is quitting but the while loop of actual_process() keeps running without stopping. It however launches setup(). But since actual_process() doesn't stop, I can not reset the parameters.

So my question would be, how can I change my code that the while loop stops ?

Answer 1

I made few changes :

• as Nearoo said, you had 2 different variables names continue_process and continue_processing with ing
• I added a call to actual_process() in setup()
• you forgot a quotation marks ' in your input(...) line
• I added a break statement when it stops , so there is not another undesired loop

You can try this :

import threading

def setup():
    global start_process, count
    count = 0
    # setting up some parameters with user inputs
    # and call actual_process()
    actual_process()

def actual_process():
    global start_process, continue_processing, count
    start_process = True
    while start_process:

        continue_processing = True

        thread_1 = threading.Thread(target=start_stop)
        thread_1.daemon = True 
        thread_1.start()

        # do something infinitely

def start_stop():
    global continue_processing, start_process
    while continue_processing:
        user_input = input('Press "r" to restart or "s" to stop:')
        if user_input == 's':
            continue_processing = False
            start_process = False
            print('closing program')
            break

        if user_input == 'r':
            continue_processing = False
            start_process = False
            print('Restarting')
            setup()

setup()

EDIT Now I do not call setup() when restarting, the global while loop while start_process: will do it automatically.

I also added an example_of_process() that increment a var count and prints it, just to simulate an infinite process that we can restart or stop.

Note that you need to press "r + Enter" to restart, and "s + Enter" to stop.

import threading
import time

def setup():
    global start_process 
    actual_process()

def actual_process():
    global start_process , continue_process, count
    start_process  = True
    count = 0
    while start_process :
        continue_process = True

        thread_1 = threading.Thread(target=start_stop)
        thread_1.daemon = True
        thread_1.start()

        example_of_process() # do something infinitely

def start_stop():
    global continue_process, start_process , count
    while continue_process:
        user_input = input('Press "r" + Enter to restart or "s" + Enter to stop: \n')
        if user_input == 's':
            continue_process = False
            start_process  = False
            print("closing program")
        if user_input == 'r':
            continue_process = False
            count = 0
            print("Restarting")

def example_of_process():
    global continue_process, count
    while continue_process:
        print("count", count)
        count += 1
        time.sleep(1)

setup()