Native mode, but packaged/frozen

[FabianGoessling]

Question

Hey,
prior to opening an issue i wanted to ask my question here, as it might be a simple error of mine. I am packaging a
an application with nicegui frontend using the shiv package. This is essentially the same as pyinstaller, i.e. zipping the site-packages of the venv, so maybe someone has an idea how to solve my problem.

As the problem only occurs after packaging, there is no easy way to reproduce the issue (needs shiv configs and so on..), so i try my best to explain. I have code as shown below with additional pywebview arguments, e.g. 'confirm_close', and a function to be run 'on_startup'.
If I execute the below code directly from my IDE this works, but after packaging the application the window_args and on_startup are not used. I dug into the nicegui source code to see what reaches the window_open() function and confirmed that the window_args reaching the pywebview call are empty.

from nicegui import ui, app

app.native.window_args['frameless'] = True #--> does not work
app.native.window_args['confirm_close'] = True #--> does not work
app.on_startup(do_some())

if __name__ == "__main__":
       ui.run(frameless=True) # --> works

I suppose this is something caused by the multiprocessing setup, but i am kind of stuck there..

Thanks for any ideas :)
Fabian

[rodja]

That is strange. Have you tried the same app with pyinstaller? Does the problem also occurs there?

[FabianGoessling]

I had some time to look into the problem in some more detail, but did not try with pyinstaller yet. Adjusting the open_window function

def open_window(
    host: str, port: int, title: str, width: int, height: int, fullscreen: bool, frameless: bool,
    method_queue: mp.Queue, response_queue: mp.Queue, **kwargs
) -> None:
    while not helpers.is_port_open(host, port):
        time.sleep(0.1)

    window_kwargs = {
        'url': f'http://{host}:{port}',
        'title': title,
        'width': width,
        'height': height,
        'fullscreen': fullscreen,
        'frameless': frameless,
        **kwargs
        # **globals.app.native.window_args, <- remove
    }
    window = webview.create_window(**window_kwargs)
    closed = Event()
    window.events.closed += closed.set
    start_window_method_executor(window, method_queue, response_queue, closed)
    webview.start(storage_path=tempfile.mkdtemp(), **globals.app.native.start_args)

and the mp Process call in the activate function to

def activate(host: str, port: int, title: str, width: int, height: int, fullscreen: bool, frameless: bool) -> None:
    def check_shutdown() -> None:
        while process.is_alive():
            time.sleep(0.1)
        globals.server.should_exit = True
        while globals.state != globals.State.STOPPED:
            time.sleep(0.1)
        _thread.interrupt_main()

    if 'native' not in globals.optional_features:
        globals.log.error('Native mode is not supported in this configuration.\n'
                          'Please run "pip install pywebview" to use it.')
        sys.exit(1)
 
    mp.freeze_support()
    args = host, port, title, width, height, fullscreen, frameless, native.method_queue, native.response_queue
    process = mp.Process(target=open_window, args=args, kwargs=globals.app.native.window_args, daemon=False) # <- add kwargs directly to the Process call
    process.start()

    Thread(target=check_shutdown, daemon=True).start()

works and the app.native.window_args are carried over as expected. Thus it seems to be a multiprocessing issue even more. Moreover the

 mp.freeze_support()

might be out of place, at least if i read the multiprocessing docs correctly (?!):

multiprocessing.freeze_support()
Add support for when a program which uses [multiprocessing](https://docs.python.org/3/library/multiprocessing.html#module-multiprocessing) has been frozen to produce a Windows executable. (Has been tested with py2exe, PyInstaller and cx_Freeze.)

One needs to call this function straight after the if __name__ == '__main__' line of the main module.

Maybe someone with more experience can make some sense out of it.

@rodja Are you 100% sure the way the nicegui.globals module is used works for the native mode window args?
I cannot test with pyinstaller on a windows machine at the moment, but maybe anyone already has?

[rodja]

mp.freeze_support() might be out of place

Yes, from the documentation it looks wired. I remember vaguely that it still was necessary to ensure the window is closing properly when I worked on #917.

Are you 100% sure the way the nicegui.globals module is used works for the native mode window args?

Yes. native_mode.activate is called from the NiceGUI main thread which has access to globals.app.native.window_args and then get passed to the mp.Process which starts the pywebview window. I've also just tested your example which worked fine (after I added reload=False as mentioned in the docs):

from nicegui import app, ui

ui.label('Hello Frameless World!')
app.native.window_args['frameless'] = True
app.native.window_args['confirm_close'] = True

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

[FabianGoessling]

Are you 100% sure the way the nicegui.globals module is used works for the native mode window args?

I was wondering about the mp.Process() because i can confirm the activate function has access, but the start_window() inside the new process gets empty i.e. the default "globals". Seems like there is a completely "fresh" init happening..

So i understand correctly you tried your example in "frozen" mode, i.e. pyinstaller? So i have to dig into shiv or just switch to pyinstaller 😂..

[chaosct]

Hi there,

I am being impacted by this very issue but without the need of compiling or freezing the code (just running with uv run). I made a pull request that solves the issue for me here: #4665

[FabianGoessling]

Hi, thanks, i did not look further and instead used my monkeypatch since. Will take a look if you PR solves my problem.

[chaosct]

Hi! In fact, I was having two separate issues. I am now having your exact issue with pyinstaller.

Can you share your monkeypatch solution? I'd prefer not to use a forked version of nicegui for production...