flask inside multiprocessing

Backend.py

import multiprocessing
import multiprocessing.queues
from flask import Flask
from flask import request

class Backend(object):
    def __init__(self, command_queue, host='0.0.0.0', port=8000, debug=True):
        self.command_queue = command_queue
        self.flask_app = Flask('Backend')
        self.flask_app.add_url_rule('/', "handleRequest", self.handleRequest, methods=['GET'])
        self.flask_app.run(host=host, port=port, debug=debug, use_reloader=False)
    def handleRequest(self):
        for key in request.args.keys():
            val = request.args.get(key, '')
            ret += str(key) + " = " + str(val) + "<br>"

        if request.method == 'POST':
            ret += "<br>Request method is POST"
        else:
            ret += "<br>Request method is GET"

        self.command_queue.put(request.args)

        return ret

def _worker(command_queue):
    print "Starting up web interface worker"
    global backend_instance
    if backend_instance == None:
        backend_instance = Backend(command_queue)

def stop():
    global backend_instance

    print "Stopping web interface worker"
    command_queue.empty()
    web_backend_process.terminate()
    backend_instance = None

def poll():
    if backend_instance != None and not backend_instance.command_queue.empty():
        return backend_instance.command_queue.get()
    else:
        return None

backend_instance = None

command_queue = multiprocessing.queues.SimpleQueue()

web_backend_process = multiprocessing.Process(None, _worker, \
    "async web interface listener", [command_queue])

web_backend_process.start()