ConnectionResetError from loading too many video elements in native browser #5443
Description
First Check
- I added a very descriptive title here.
- This is not a Q&A. I am sure something is wrong with NiceGUI or its documentation.
- I used the GitHub search to find a similar issue and came up empty.
Example Code
from collections.abc import Awaitable, Callable
import anyio
from nicegui import app, ui
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.requests import Request
from starlette.responses import Response
class IgnoreClientDisconnect(BaseHTTPMiddleware):
async def dispatch(self, request: Request, call_next: Callable[[Request], Awaitable[Response]]) -> Response:
try:
return await call_next(request)
except RuntimeError as exc:
if str(exc) == "No response returned.":
# client closed the connection; return a 499-like response
return Response(status_code=499)
raise
except anyio.EndOfStream:
return Response(status_code=499)
def main() -> None:
for _ in range(20):
ui.video("test.mp4")
app.add_middleware(IgnoreClientDisconnect)
ui.run(main, native=True, reload=False)Description
Start the app.
The videos load properly, but there is visible lag, and we get the following error:
Exception in callback _ProactorBasePipeTransport._call_connection_lost()
handle: <Handle _ProactorBasePipeTransport._call_connection_lost()>
Traceback (most recent call last):
File "C:\Users\Cookie\AppData\Local\Python\pythoncore-3.14-64\Lib\asyncio\events.py", line 94, in _run
self._context.run(self._callback, *self._args)
~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\Cookie\AppData\Local\Python\pythoncore-3.14-64\Lib\asyncio\proactor_events.py", line 165, in _call_connection_lost
self._sock.shutdown(socket.SHUT_RDWR)
~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
ConnectionResetError: [WinError 10054] An existing connection was forcibly closed by the remote hostEverything works properly to the user, but closing the native window doesn't ever cause the terminal to close. It also becomes impossible to Ctrl+C or Ctrl+Z out of the terminal. Even calling app.shutdown() does not always close the terminal. These problems get worse as the number of videos are increased.
NiceGUI Version
3.2.0
Python Version
Python 3.14.0
Browser
Other
Operating System
Windows
Additional Context
This is an issue we have specifically noticed when working with large numbers of video files. I can confirm this error does not occur even when adding an unrealistic number of buttons, which suggests it has something to do with how the videos are loaded and could be caused by the same thing as #4970. Which is to say, likely something to do with the loading/rendering of the video is not being handled asynchronously and results in blocking.
Compared to loading images, the UI appears to freeze for the duration of loading the videos instead of it happening asynchronously. Even loading an unrealistic number of (animated) images doesn't cause this error either. Doing so also doesn't cause the error from #4970. It is only videos from the tests we have done that have this problem.
This is probably the same issue as #3961, but the solution no longer works from tests we have done. Regardless, it is deprecated with Python 3.14 and is scheduled for removal.
This is also building off issue #4970 and using the this solution from the comments there. However, since this is a separate error, we figured we should make a new issue for it.
(Not sure if there is a better way to link specific comments).