How to setup flask server?

Question

Flask

Achtung! Help, I have a Flask server, the main task of which is to call a script in the system with the parameter passed in the request. Here is the code:

import subprocess
from flask import Flask
from flask import Response

app = Flask(__name__)

@app.route("/<url>", methods=['GET'])
def index(url):
  cmd = './prg '
  cmd = cmd + url
  PIPE = subprocess.PIPE
  p = subprocess.Popen(cmd, shell=True, stdin=PIPE, stdout=PIPE,
          stderr=subprocess.STDOUT, close_fds=True, cwd='/home/prog')
  resp = Response(p.stdout.read())
  resp.headers['Access-Control-Allow-Origin'] = '*'
  return resp 

if __name__ == "__main__":
    context = ('/var/www/httpd-cert/www-root/cert.crt', '/var/www/httpd-cert/www-root/cert.key')
    app.run(host='0.0.0.0', port=9090, ssl_context=context)

I ran into a problem, my server crashes after accessing it, what could be the reason for this? How to set up this process optimally? It is worth noting that the program that is called is computationally expensive and works quite a lot, while using all the available cores. (sometimes up to several minutes)

Answer 1

You have done it wrong. You cannot block the execution thread in flask, since it is single-threaded, then you completely hang the server until the rendering of your task. For your task, you need to run a process in parallel, add the data of this process, for example, to a separate database or file, and immediately give the result with the number of your process.
To do this, you can use some simple task queue like python-rq.org