Python. Flask. Get list after click

Question

I have a simple code that runs a function in the process. This function append numbers to the list. In my version of the code, I get an empty list. How to get this list after clicking on the stop button?

from multiprocessing import Process
from flask import Flask

app = Flask(__name__)

logs = []

def test():
    for i in range(100):
        logs.append(i)
        time.sleep(1)


@app.route('/', methods=['POST', 'GET'])
def main():

    global p

    if request.method == 'POST':

        index = request.form['index']

        if index == 'start':

            p = Process(target = test)
            p.start()

        if index == 'stop':

            print(logs)
            p.kill()

        return redirect(url_for('main'))

    return render_template('index.html')

app.run(debug=True)

Does this answer your question? [Globals variables and Python multiprocessing](https://stackoverflow.com/questions/11215554/globals-variables-and-python-multiprocessing) — Alex028502, Nov 08 '21 at 07:41

score 0 · Answer 1 · answered Nov 08 '21 at 07:47

0

You have chosen the wrong way. First that you have missed, not only one user will use your site, so all of them will see the result of one counting, even if it will be working.

So, would I suggest here, for example, use DB, create a record with timestamp for each particular user when user loads the page first time, and once user pressed the button, find the difference between now and recorded time.

answered Nov 08 '21 at 07:47

mrvol

2,575
18
21

There will only be one user – Dmitry Nov 08 '21 at 08:23

score 0 · Answer 2 · answered Nov 08 '21 at 07:47

I bet you this will work though!

from threading import Thread
from flask import Flask

app = Flask(__name__)

logs = []

stop_thread = False

def test():
    for i in range(100):
        if stop_thread:
            return
        logs.append(i)
        time.sleep(1)


@app.route('/', methods=['POST', 'GET'])
def main():

    global stop_thread

    if request.method == 'POST':

        index = request.form['index']

        if index == 'start':

            t = Thread(target = test)
            t.start()

        if index == 'stop':

            print(logs)
            stop_thread = True;

        return redirect(url_for('main'))

    return render_template('index.html')

app.run(debug=True)

yeah I just meant that to show the difference between how threads and processes access global variables — Alex028502, Nov 08 '21 at 11:23

Python. Flask. Get list after click

2 Answers2