Proper way to kill a thread

Question

What I am trying to do:

I am trying to kill a thread that has an infinite loop from a parent process launched. I want the child process to be killed as soon as I change the variable.

What I have done so far:

I have shared a variable with the two threads and once the loop gets the stop signal it stops.

Whats not working:

It is not killing the thread as soon as I send the stop signal

Here is some sample code:

from flask import Flask, flash, redirect, render_template, request, session, abort
import light_control
import logging
import thread
app = Flask(__name__)
log = logging.getLogger('werkzeug')
log.setLevel(logging.ERROR)
global stop 
stop = False

def loop_rainbow_cycle_successive(name):
    global stop
    while 1:
        if stop == True:
            break
        light_control.rainbow_cycle_successive()

def loop_rainbow_cycle(name):
    global stop
    while 1:
        if stop == True:
            break
        light_control.rainbow_cycle()

def loop_rainbow_colors(name):
    global stop
    while 1:
        if stop == True:
            break
        light_control.rainbow_colors()

RGB = ()
@app.route("/")
def index():
     return render_template(
        'index.html')
@app.route("/getColor/", methods=['POST'])
def getColor():
    RGB = (request.form['r'],request.form['g'],request.form['b'])
    light_control.setColor(RGB)
    return render_template('index.html')
@app.route("/useFunction/", methods=['POST'])
def useFunction():
    global stop
    stop = False
    func = request.form['function']
    if func == "rainbow_cycle_successive":
        thread.start_new_thread( loop_rainbow_cycle_successive, ("loop_rainbow_cycle_successive", ))
    elif func == "rainbow_cycle":
        thread.start_new_thread( loop_rainbow_cycle, ("loop_rainbow_cycle", ))
    elif func == "rainbow_colors":
        thread.start_new_thread( loop_rainbow_colors, ("loop_rainbow_cycle", ))
    elif func == "STOP":
        stop = True

    return render_template('index.html')
if __name__ == "__main__":
    app.run(host='0.0.0.0', port=8080)

Possible duplicate of [Is there any way to kill a Thread in Python?](https://stackoverflow.com/questions/323972/is-there-any-way-to-kill-a-thread-in-python) — Ryan Schaefer, Mar 03 '18 at 23:15
You are using words *thread* and *process* interchangeably. That is wrong. There are ways to kill a process if you really really have to, but you should never have to kill a thread. Also, I don't see in your code that you are killing either of them. — zvone, Mar 04 '18 at 00:17
@zvone Thank you. You are correct. I found the solution to my question. I am will use p.terminate. — Kevin, Mar 04 '18 at 01:03

score 0 · Accepted Answer · answered Mar 04 '18 at 01:04

You can make it a process and use p.terminate()

code:

from flask import Flask, flash, redirect, render_template, request, session, abort
import sys, os
sys.path.append(os.getcwd() + '/audio-reactive-led-strip/python/')#append entire directory
import logging
import multiprocessing
import light_control, visualization

app = Flask(__name__)
log = logging.getLogger('werkzeug')
log.setLevel(logging.ERROR)
global stop 
stop = False
p = multiprocessing.Process()

def terminate_process():
    global p
    if p.is_alive():
        p.terminate()
def loop_rainbow_cycle_successive(name):
    global stop
    while 1:
        if stop == True:
            break
        light_control.rainbow_cycle_successive()

def loop_rainbow_cycle(name):
    global stop
    while 1:
        if stop == True:
            break
        light_control.rainbow_cycle()

def loop_rainbow_colors(name):
    global stop
    while 1:
        if stop == True:
            break
        light_control.rainbow_colors()
def loop_visualization(name):
    # Initialize LEDs
    visualization.led.update()
    # Start listening to live audio stream
    visualization.microphone.start_stream(visualization.microphone_update)

RGB = ()
@app.route("/")
def index():
     return render_template(
        'index.html')
@app.route("/getColor/", methods=['POST'])
def getColor():
    terminate_process()
    RGB = (request.form['r'],request.form['g'],request.form['b'])
    light_control.setColor(RGB)
    return render_template('index.html')
@app.route("/useFunction/", methods=['POST'])
def useFunction():
    global stop
    global p
    stop = False
    func = request.form['function']
    if func == "rainbow_cycle_successive":
        terminate_process()
        p = multiprocessing.Process(target=loop_rainbow_cycle_successive, args=("loop_rainbow_cycle_successive", ))
        p.start()

    elif func == "rainbow_cycle":
        terminate_process()
        p = multiprocessing.Process(target=loop_rainbow_cycle, args=("loop_rainbow_cycle", ))
        p.start()

    elif func == "rainbow_colors":
        terminate_process()
        p = multiprocessing.Process(target=loop_rainbow_colors, args=("loop_rainbow_cycle", ))
        p.start()
    elif func == "visualization":
        terminate_process()
        p = multiprocessing.Process(target=loop_visualization, args=("loop_visualization", ))
        p.start()
    elif func == "STOP":
        stop = True
        terminate_process()

    return render_template('index.html')
if __name__ == "__main__":
    app.run(host='0.0.0.0', port=8080)

Proper way to kill a thread

1 Answers1