Flask Client-Server Connection Timeout after given time

Question

I have a flask app. I want the client-server connection to terminate if the server does not respond within a stipulated time (say 20 seconds). I read here that the session.permanent = True can be set. I am a bit unclear where this goes in the server side code (if at all this is the way??).

For simplicity I am including the minimal server side code I have. Actually the server is performing a File Read/Write operation and returning a result to the client.

from flask import Flask, session, app
from flask_restful import Api, Resource
from datetime import timedelta

app = Flask(__name__)
api = Api(app)

class GetParams(Resource):
    def get(self):
        print ("Hello.")
        return 'OK'

api.add_resource(GetParams, '/data') 
if __name__ == '__main__':
    app.run(host='127.0.0.1', port=5002) 

Can anyone tell me what should I do here so that the connection between my client and server is terminated if the server does not respond i.e., send data back to the client within 20 seconds?

Answer 1

I believe that the only thing you need is to put your connexion statement in a try/except block. So that you will be able to handle any kind of connexion error.

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Furthermore, a session timeout and a connexion fail/unreachable server are different things. A session timeout disconnect a user from a server which is here for too long (usually used to avoid a user to forgot a session open). Whereas when a server is unreachable the user isn't connected so there is no session timeout.

---

from flask import Flask, session, app
from flask_restful import Api, Resource
from datetime import timedelta

app = Flask(__name__)
api = Api(app)

class GetParams(Resource):
    def get(self):
        print ("Hello.")
        return 'OK'

api.add_resource(GetParams, '/data') 
if __name__ == '__main__':
      try:
         app.run(host='130.0.1.1', port=5002)
      except:
         print("unexcepted error")

you could qualify the received exception, but you'll have to read a bit of doc http://flask.pocoo.org/docs/1.0/quickstart/#what-to-do-if-the-server-does-not-start

Answer 2

Long running tasks should be dealt with in a different design because, if you allow your server to keep a request alive for 50 minutes, you can't force user browser to do so.

I would recommend implementing the long running task as a thread that notifies the user once it's done.

For more readings about the problem statement and suggested solutions:

1. timeout issue with chrome and flask
2. long request time patterns