Can't stop aiohttp websocket server - python-3.x

Question

I can't cancel my aiohttp websocket server from within the application. I want to stop the server and shutdown when I get a "cancel" string
from the client. Yes, I get it, and I finish my co-routine (websocket_handler), but there are three co-routines from the aiohttp library which still continue working.
Of course, I can invoke asyncio.get_event_loop().stop() at the end of my co-routine, but is there a graceful way for stopping aiohttp server?
From my code one can see that I've tried to use Application().on_shutdown.append(), but it failed.
What is the right way?
#!/usr/bin/env python
# -- coding: utf-8 --
import os
import asyncio
import signal
import weakref
import aiohttp.web
from aiohttp import ClientConnectionError, WSCloseCode
# This restores the default Ctrl+C signal handler, which just kills the process
#https://stackoverflow.com/questions/27480967/why-does-the-asyncios-event-loop-suppress-the-keyboardinterrupt-on-windows
import signal
signal.signal(signal.SIGINT, signal.SIG_DFL)
HOST = os.getenv('HOST', 'localhost')
PORT = int(os.getenv('PORT', 8881))
async def testhandle(request):
#Сопрограмма одрабатывающая http-запрос по адресу "http://127.0.0.1:8881/test"
print("server: into testhandle()")
return aiohttp.web.Response(text='Test handle')
async def websocket_handler(request):
#Сопрограмма одрабатывающая ws-запрос по адресу "http://127.0.0.1:8881"
print('Websocket connection starting')
ws = aiohttp.web.WebSocketResponse()
await ws.prepare(request)
request.app['websockets'].add(ws)
print('Websocket connection ready')
try:
async for msg in ws:
if msg.type == aiohttp.WSMsgType.TEXT:
if msg.data == 'close':
print(msg.data)
break
else:
print(msg.data)
await ws.send_str("You said: {}".format(msg.data))
elif msg.type == aiohttp.WSMsgType.ERROR:
print('ws connection closed with exception %s' %
ws.exception())
except (asyncio.CancelledError, ClientConnectionError):
pass # Тут оказываемся когда, клиент отвалился.
# В будущем можно тут освобождать ресурсы.
finally:
print('Websocket connection closed')
request.app['websockets'].discard(ws)
#pending = asyncio.Task.all_tasks()
#asyncio.get_event_loop().stop()
return ws
async def on_shutdown(app):
for ws in set(app['websockets']):
await ws.close(code=WSCloseCode.GOING_AWAY, message='Server shutdown')
def main():
loop = asyncio.get_event_loop()
app = aiohttp.web.Application()
app['websockets'] = weakref.WeakSet()
app.on_shutdown.append(on_shutdown)
app.add_routes([aiohttp.web.get('/', websocket_handler)]) #, aiohttp.web.get('/test', testhandle)
try:
aiohttp.web.run_app(app, host=HOST, port=PORT, handle_signals=True)
print("after run_app")
except Exception as exc:
print ("in exception")
finally:
loop.close()
if __name__ == '__main__':
main()

Answer 1

I believe the correct answer is simply:
raise aiohttp.web.GracefulExit()
After catching the exception, it calls all the handlers appended to the on_shutdown and on_cleanup signals and dies.
One can see in the source code the aiohttp.web.run_app() waits for two exceptions: GracefulExit and KeyboardInterrupt. While the latter is rather uninteresting, following the trace of GracefulExit can lead you to this place in web_runner.py, that registers SIGINT and SIGTERM signal handlers to a function with raise GracefulExit().
Indeed, I also managed to gracefully shut it down by raising the signal.SIGINT or signal.SIGTERM from itself, e.g.
import signal
signal.raise_signal(signal.SIGINT)
This was tested to work on Fedora Linux 34, Python 3.9.7, aiohttp 3.7.4.

Answer 2

https://docs.aiohttp.org/en/v3.0.1/web_reference.html#aiohttp.web.Application.shutdown
app.shutdown()
app.cleanup()
After shutdown you should also do cleanup()