I am currently testing out aiohttp and I am having a problem with the following code:
async def index(request: web.Request) -> web.StreamResponse:
response = web.StreamResponse(headers={'content-type': 'text/plain'})
await response.prepare(request)
for i in range(1000000):
try:
response.write(b'test response')
await response.drain()
except concurrent.futures.CancelledError:
print('Remote connection closed... Cleaning up...')
# Do cleanup process here?
raise
return response
Now I try this out with the following curl request:
curl -v http://127.0.0.1:8080
And then I hit Ctrl-C to cause curl to disconnect and stop downloading the response.
On the console log from the aiohttp web server I get a lot of the following:
2017-11-08 14:42:31,295|WARNING|asyncio|socket.send() raised exception.
2017-11-08 14:42:31,295|WARNING|asyncio|socket.send() raised exception.
2017-11-08 14:42:31,295|WARNING|asyncio|socket.send() raised exception.
2017-11-08 14:42:31,295|WARNING|asyncio|socket.send() raised exception.
2017-11-08 14:42:31,295|WARNING|asyncio|socket.send() raised exception.
Which keeps looping and I cannot kill the server with Ctrl-C. I have to kill it with kill -KILL in order to fully terminate it. It seems that the client socket disconnection is silently handled. I would like to silence the above warnings which are thrown by asyncio.selector_events._SelectorSocketTransport.write(). I could silence that by setting the appropriate logger level, but that's not what I want. Plus there's a lot of cleanup procedures that I would like to do when a client connection terminates. I have looked through the aiohttp code and there doesn't seem to be any handlers or signals that I can hook into to handle it. Ideally I would like to be able to do some cleanup when a client connection is closed.
In Django I am able to do it by creating a custom SelfCleaningStream class with the StreamingHttpResponse class. The custom SelfCleaningStream class handles the cleanup in the close() method which is called by Django when a client connection is closed.
Thanks for report. It is a bug in aiohttp, I've filed an issue