🔒 App freezes and crashes when I attempt to run a flask-socketio server. (please help)

[dry ivy]

I'm making a desktop app for myself and a couple buddies to assist in a dnd campaign we're trying to run figured it would be a good way to learn some new skills, but thats unimportant.

Long story short, the application opens fine but when I click the 'Host' button in the app, it freezes, yet the server still starts, or at the bare minimum, I can see its getting requests. I originally attempted using asyncio to try and mitigate these problems since i have a hunch the problem is being caused because starting the server is not apart of the main loop required to keep the gui up but tkinter doesnt like asyncio and so I turned to threading which i've had some luck on but it still isnt working. Any input would be appreciated; sorry if theres no reply, its late and im tired.

P.S: Sorry for the messy code and documentation, organization was never my strong suit.

https://paste.pythondiscord.com/PSWA

[craggy orbit]

@dry ivy

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[hallow hill]

Yeah, sio.run(..) starts the mainloop for the server. This is called inside tkinter's mainloop, which is now blocked, so the server continues to run but your GUI will freeze

I'm not too familiar with neither tkinter nor socketio/flask, but from a brief search it seems it should be fine to run the flask app in a separate thread

I did notice that you did something like that with the "Connect" button, which calls Thread_Serv, which does start a server in a separate thread

The Host button does not do that though, it calls the blocking function directly

I also read that you need to disable the reloader flask uses, as it requires flask to run on the main thread: sio.run(..., use_reloader=False)

[dry ivy]

So if I’m understanding correctly I should start sio.run() in a thread to not block the tkinter main loop. Sound about right?

As for the connect button, I think I did that on accident and I meant to swap it to the other button, though I could be wrong. Edit: button was my screw up upon a second look

And I will make sure to try the reloader.

[hallow hill]

Yeah. Have the function that starts the server start it in a new thread. This could be as simple as calling .run as part of threading.Thread(), for example: ```py
server_thread = threading.Thread(target=lambda: app.run(app, host='0.0.0.0', port=8080, use_reloader=False))
server_thread.start()

getting communication working between tkinter and flask might be a bit of a challenge, since you can't just call flask methods from tkinter, or tkinter methods from flask.

you'd have to do something like put commands/events in a queue and have flask and tkinter consume events from it to communicate

but that is mostly a guess on my part, this is an area I'm not familiar with

[dry ivy]

Alright, sweet, thanks for the help! I’m gonna head to bed now but I got confidence this will work, and at the very least, I got places to start. Again, thanks for all the help!

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