call_on_close.py

from time import sleep

from flask import Flask, Response, request


app = Flask('hello')


@app.route('/')
def hello():

    response = Response('hello %s' % request.args['hello'])

    @response.call_on_close
    def on_close():
        for i in range(10):
            sleep(1)
            print i

    return response


if __name__ == '__main__':
    app.run(debug=True, port=5001)