Run while loop concurrently with Flask server

Question

I\'m updating some LEDs using python. I\'ve been doing this like so:

from LEDs import *
myLEDs = LEDs()
done = False
while not done:
  myLEDs.iterate()


        

Answer 1

Use multiprocess to run the loop in a different process as the Flask HTTP requests:

import time
from flask import Flask, jsonify
from multiprocessing import Process, Value


app = Flask(__name__)


tasks = [
   {
      'id': 1,
      'title': u'Buy groceries',
      'description': u'Milk, Cheese, Pizza, Fruit, Tylenol', 
      'done': False
   },
   {
      'id': 2,
      'title': u'Learn Python',
      'description': u'Need to find a good Python tutorial on the web', 
      'done': False
   }
]


@app.route('/todo/api/v1.0/tasks', methods=['GET'])
def get_tasks():
   return jsonify({'tasks': tasks})


def record_loop(loop_on):
   while True:
      if loop_on.value == True:
         print("loop running")
      time.sleep(1)


if __name__ == "__main__":
   recording_on = Value('b', True)
   p = Process(target=record_loop, args=(recording_on,))
   p.start()  
   app.run(debug=True, use_reloader=False)
   p.join()

The tasks part is from here, multiprocessing code from me.
Note the "use_reloader=False" part. This is necessary to avoid running the loop twice. For the reason see here

The functionality can be tested by starting up the server with

python <your_name_for_the example>.py

and calling

curl -i http://localhost:5000/todo/api/v1.0/tasks

Answer 2

Although I am not the most qualified to comment here: I think this might help you.

How to run recurring task in the Python Flask framework?