CODEWITHSUNDEEP
pythonflaskwsgi
Antonio
Antonio

Reputation: 71

Properly integrate wsgiref.simple_server and Flask in a desktop app

I have problems with the integration of a Flask app served by a wsgiref.simple_server in a Desktop app.

Our problem is that we have to start and stop the server when the user enter in a special software area that show the app via CEF browser.

All works well except when we have to stop and start the app.

One strange thing happen with a code like this:

import os
import time
import threading
from wsgiref.simple_server import make_server
from flask import Flask


def start(host='127.0.0.1', port=5000, app=None):
    global SERVER, THREAD

    SERVER = make_server(host, port, app)
    SERVER.timeout = 1
    threading.Thread(target=SERVER.serve_forever, daemon=True).start()

def stop():
    global SERVER
    SERVER.shutdown()

def get_app():
    APP = Flask(__name__)

    @APP.route("/")
    def hello():
        return "Hello World!"

    return APP


if __name__ == '__main__':

    print("First start", flush=True)
    start("0.0.0.0", 5000, get_app())

    time.sleep(10)
    print("Start stop procedure", flush=True)
    stop()
    print("Stop", flush=True)


    print("Second start", flush=True)
    start("0.0.0.0", 5000, get_app())

    time.sleep(10)
    print("Start stop procedure", flush=True)
    stop()
    print("Stop", flush=True)

The very strange is that I need a request before the server understand that have to shutdown

$ python test.py                                            
First start                                                 
127.0.0.1 - - [29/Oct/2018 17:04:36] "GET / HTTP/1.1" 200 12
Start stop procedure                                        
127.0.0.1 - - [29/Oct/2018 17:04:46] "GET / HTTP/1.1" 200 12 # the unwanted request
Stop                                                        
Second start                                                
127.0.0.1 - - [29/Oct/2018 17:04:56] "GET / HTTP/1.1" 200 12
Start stop procedure                                        
127.0.0.1 - - [29/Oct/2018 17:05:01] "GET / HTTP/1.1" 200 12# the unwanted request
Stop

I can't have control on that. This doesn't happen with custom made wsgi app.

Is there a proper way to stop and start a Flask app? All solution on the net seem to not work

Upvotes: 0

Views: 908

Answers (1)

scvnc
scvnc

Reputation: 1040

I suspect we need to use the poll_interval param for the serve_forever function.

This solution seems to work for me

import time
import threading
from wsgiref.simple_server import make_server
from flask import Flask


def get_app():
    APP = Flask(__name__)

    @APP.route("/")
    def hello():
        return "Hello World!"

    return APP


class WsgiRefServer(threading.Thread):

    def __init__(self, wsgi_app, host='127.0.0.1', port=5000):
        super().__init__()

        self._server = make_server(host, port, wsgi_app)

    def run(self):
        self._server.serve_forever(poll_interval=0.5)

    def stop(self):

        self._server.shutdown()
        self.join()


if __name__ == '__main__':

    http_thread = WsgiRefServer(get_app())

    http_thread.start()
    time.sleep(10)
    http_thread.stop()

Upvotes: 1

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