Weird socket issues with Upload File Route (Task exception was never retrieved, OSError: [WinError 64])

[Cacsjep]

Hey Guys,

We have a very weird issue on our file upload route, sometimes with bad network connections (lost) it happens that we encounter a "Task exception was never retrieved" Message followed by a Socket Error (OSError: [WinError 64] The specified network name is no longer available)

Issue happen with unicorn and hypercorn, and only happens on a file upload route.

Minimal Example to reproduce

1. Start Server
2. Start Client (You need a test.jpg)
3. Close Client after one second with Ctrl+C to simulate a connection lost

I would ask if you guys can help me to find the root couse of this issue, or give me hints about that.

BR

Server:

import uvicorn
from starlette.applications import Starlette
from starlette.responses import JSONResponse
from starlette.routing import Route


async def test_case(request):
    await request.form()
    return JSONResponse({'hello': 'world'})

routes = [
    Route("/", endpoint=test_case, methods=['POST'])
]

uvicorn.run(
    Starlette(debug=True, routes=routes),
    reload=False,
    log_level="error",
    host="0.0.0.0",
    port=8088,
)

Client:

import threading
import requests

def create():
    for i in range(100):
        test_files = { "image": open("test.jpeg", "rb")}
        r = requests.post("http://127.0.0.1:8088/", files=test_files)

if __name__ == "__main__":
    threads = []
    for i in range(100):
        thread = threading.Thread(target=create, args=(), daemon=True)
        thread.start()
        threads.append(thread)

Error:

ERROR  Task exception was never retrieved
future: <Task finished name='Task-15680987' coro=<IocpProactor.accept.<locals>.accept_coro() done, defined at C:\Program Files\Python39\lib\asyncio\windows_events.py:568> exception=OSError(22, 'The specified network name is no longer available', None, 64, None)>
Traceback (most recent call last):
  File "C:\Program Files\Python39\lib\asyncio\windows_events.py", line 571, in accept_coro
    await future
  File "C:\Program Files\Python39\lib\asyncio\windows_events.py", line 817, in _poll
    value = callback(transferred, key, ov)
  File "C:\Program Files\Python39\lib\asyncio\windows_events.py", line 560, in finish_accept
    ov.getresult()
OSError: [WinError 64] The specified network name is no longer available

ERROR  Accept failed on a socket
socket: <asyncio.TransportSocket fd=1192, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=6, laddr=('0.0.0.0', 8088)>
Traceback (most recent call last):
  File "C:\Program Files\Python39\lib\asyncio\proactor_events.py", line 819, in loop
    conn, addr = f.result()
  File "C:\Program Files\Python39\lib\asyncio\windows_events.py", line 571, in accept_coro
    await future
  File "C:\Program Files\Python39\lib\asyncio\windows_events.py", line 817, in _poll
    value = callback(transferred, key, ov)
  File "C:\Program Files\Python39\lib\asyncio\windows_events.py", line 560, in finish_accept
    ov.getresult()
OSError: [WinError 64] The specified network name is no longer available

Windows 10 Pro
python 3.9.13
starlette 0.20.3
uvicorn 0.17.6
hypercorn: 0.13.2
No Antivirus is installed and Windows Defender is also off

[Cacsjep]

I have created a bug report on cpython because I think maybe its more releated to cpython, we will see =), also the report is updated with more findings.
python/cpython#93821