How to run a function and continue the work of the main program without waiting for its completion?

Question

Python

The bottom line is, there is a script using Flask in the main() function, under a certain condition, the function() function is launched. I need this function to start working when called, but at the same time, the main function returns the value value without waiting for the function () to complete. I so understood, it is necessary to use asynchronous programming. Tried to use asyncio but didn't work for me.

import ...
app = Flask(__name__)
logging.basicConfig(level=logging.DEBUG)
@app.route("/", methods=['POST', 'GET'])
def main():
  
  value = a + b
        if value >=2:
                fucntion()
  return value

app.run()

Answer 1

If done in a human way, then of course Celery.
But if you don't want to fence the garden with Celery and the main thing for you is to run the function, then you can put it in a separate file and run it through subprocess
For example, put two files side by side.

from flask import Flask
import subprocess

app = Flask(__name__)


@app.route("/")
def main():
    subprocess.Popen('python mysleep.py', shell=True, executable='/bin/bash')
    return "Hello"


if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0')

import time

time.sleep(10)
print("zzzzzzzzzzzz")

Answer 2

Flask is designed to be single-threaded and synchronous, using multi-threading or asynchrony can lead to problems. Use Celery and the like.