When native is True and reload is True, port is ignored and app_shutdown never fires

[PawelRoman]

Description

Platform:
Linux Mint 20.03 (ubuntu)
NiceGUI 1.4.3

Steps to replicate:
Save the code below as main.py and run python main.py

from nicegui import app, ui

def app_startup():
    print('app startup')

def app_shutdown():
    print('app shutdown')

app.on_startup(app_startup)
app.on_shutdown(app_shutdown)

ui.run(
    title="Some app",
    port=8502,
    native=True,
    reload=True,
    window_size=(1920, 1200),
    storage_secret='my secret'
)

Expected: Window app opens up, server starts on port 8502, app startup printed out.
Actual: Window app opens up, app startup printed out, but server starts on port 8000 (note: I double checked that 8502 is NOT taken by some other process)

Then close the window by clicking "X"

Expected: app shutdown printed out
Actual: nothing is printed out, the app_shutdown function is never called

[retsyo]

Currently, port is not used in native mode as #1457 stated. I have made a pull request to change this.

However, I don't know why app_shutdown never fires.

[rodja]

Thanks @retsyo. On Mac M1 the shutdown works as expected. Are you running on Windows @PawelRoman? Does the shutdown work if you disable reload? What does happen when you use the buttons

ui.button('destroy window', on_click=lambda: app.native.main_window.destroy())
ui.button('nicegui shutdown', on_click=lambda: app.shutdown())

[retsyo]

On my windows 10 64 bits, both buttons close the window and python

ui.button('destroy window', on_click=lambda: app.native.main_window.destroy())
ui.button('nicegui shutdown', on_click=lambda: app.shutdown())

ui.run(reload=False, native=True)

and PawelRoman's code runs app_shutdown too if reload=False

def app_shutdown():
    print('app shutdown')

app.on_shutdown(app_shutdown)
ui.run(reload=False, native=True)

so does reload=True conflict with app.on_shutdown?

[rodja]

I fear this must be debugged on a Windows system. On Mac the demo you provided prints the shutdown message. Any help would be appreciated.

[PawelRoman]

As I wrote in the original post, I work on Ubuntu 20 (Linux Mint).

The on_shutdown issue gets fixed when I set reload to False, with reload=True, the on_shutdown does not fire at all. Would also be great if the port issue fix be merged asap, as it's very annoying in certain scenarios not being able to select specific port.

[frankhuurman]

@PawelRoman thanks for the port fix :) saw that it got merged

Tried your examples on a Win 10 machine & python 3.11, came to the same conclusion that the app startup does get printed and the app shutdown doesn't fire with reload=True unless I Ctrl+C the app, when I set reload=False it fires without having to use Ctrl+C.

So that means on both Linux Mint & Win 10 the shutdown event doesn't seem to trigger with reload set to True.

Perhaps the reload/directory&file watcher functionality makes uvicorn spawn a watcher thread and won't let go of it unless Ctrl+C'd?

[falkoschindler]

Uvicorn just fixed encode/uvicorn#2289 and released version 0.30.0.
Can anyone check if this by any chance also fixes our issue?