Intrinsic high CPU usage

[me21]

Description

I was running the example from https://github.com/zauberzeug/nicegui/blob/main/examples/authentication/main.py

The only change I made was adding show=False to ui.run invocation to avoid opening the browser window automatically.

I found that after loading the page, occasionally the CPU usage of Python goes up to 12-14% on my laptop which is almost 1 CPU core out of 6. I also noticed that it can be more or less reliably triggered by refreshing the web page twice in quick succession (by tapping F5 key).

On subsequent page refresh the CPU usage goes down.

It's not 100% reproducible but like 80%.

My experiments were done on http://127.0.0.1:8080/login URL (I was not logged in).

It's not related to AuthMiddleware, as commenting out app.add_middleware(AuthMiddleware) line only made the issue harder to reproduce, but it's still happens if I refresh the page 10-20 times quickly by abusing F5 key.

My laptop runs Windows 10 22H2 and NiceGUI was installed in a virtual environment (version 1.4.19).

[falkoschindler]

Hi @me21, this reminds me of #2482. Could this be the same issue?

[me21]

@falkoschindler it's possible. The login page in the example is wrapped into @ui.page('/login') decorator.

[vickorian]

I'm in the same boat here. I'm wrapping the pages within a fastapi app and am noticing the same behavior where refreshes can solve the problem with every other refresh solving the problem. I checked the process handles and they are constant regardless of performance, so it's not spinning up any extra handles or dropping any handles there.

I have a resize function tied to an aggrid inside the @ui.page('/'), but when i attach a timer to it, i'm not seeing a refresh rate above what you would expect, so the ui.on('resize') at least is registering events correctly. So i'm guessing there's a function in the routing that isn't being handled correctly.

I have mine set up within a fastapi app and that index page is mapped with an async.
@ui.page('/')
async def index_page(...) -> None:

I thought it might have been in the wrapper, but if it was a miscode then the functionality would remain regardless of refreshes. removing the async from the page def doesn't solve the problem either.

Windows 10
python 3.9.18150.1013
NIceGUI 1.4.20.dev0

[falkoschindler]

@me21, @vickorian We're working on a fix for #2482, see PR #2867.
Maybe you can try it out and let us know if it resolves this issue as well?

[vickorian]

@falkoschindler, @me21 seems to work. I'll run with this branch to make sure there aren't any major problems or weird bugs that i haven't seen yet.

pip install git+https://github.com/zauberzeug/nicegui@refs/pull/2867/head

[falkoschindler]

I'll close this issue, assuming it has been fixed with #2482 and PR #2867.

[me21]

Sure. It is included in 1.4.24, right?