Start a flask application in separate thread

Question

I\'m currently developing a Python application on which I want to see real-time statistics. I wanted to use Flask in order to make it easy to use and to underst

Answer 1

From the werkzeug documentation:

Shutting Down The Server

New in version 0.7.

Starting with Werkzeug 0.7 the development server provides a way to shut down the server after a request. This currently only works with Python 2.6 and later and will only work with the development server. To initiate the shutdown you have to call a function named 'werkzeug.server.shutdown' in the WSGI environment:

def shutdown_server(environ):
    if not 'werkzeug.server.shutdown' in environ:
        raise RuntimeError('Not running the development server')
    environ['werkzeug.server.shutdown']()

Answer 2

If you are looking for accessing iPython terminal in Flask run your application in a separate thread. Try this example:

from flask import Flask                                                         
import thread

data = 'foo'
app = Flask(__name__)

@app.route("/")
def main():
    return data

def flaskThread():
    app.run()

if __name__ == "__main__":
    thread.start_new_thread(flaskThread, ())

(Run this file in iPython)

Answer 3

Updated answer for Python 3 that's a bit simpler:

from flask import Flask                                                         
import threading

data = 'foo'
app = Flask(__name__)

@app.route("/")
def main():
    return data

if __name__ == "__main__":
    threading.Thread(target=app.run).start()

Answer 4

You're running Flask in debug mode, which enables the reloader (reloads the Flask server when your code changes).

Flask can run just fine in a separate thread, but the reloader expects to run in the main thread.

---

To solve your issue, you should either disable debug (app.debug = False), or disable the reloader (app.use_reloader=False).

Those can also be passed as arguments to app.run: app.run(debug=True, use_reloader=False).