trio.ClosedResourceError when trying to use simple server example

[danlkv]

Hello!

what I do

I use simple server example from here https://trio-websocket.readthedocs.io/en/stable/servers.html
and try to test how fast can it get. I use server code from that page just with added print line.

in one console I do python test_server.py

In another console (2) i do yes | pv | websocat ws://localhost:8000 >dev/null

where websocat is a handy cli tool for websocket https://github.com/vi/websocat.

what I get

I successfully get a bunch of 'y' in the output. Hovewer, when I interrupt
console (2) to close the connection, the server crashes with following error

    await serve_websocket(echo_server, 'localhost', 8000, ssl_context=None)
  File "/usr/lib/python3.8/site-packages/trio_websocket-0.8.0-py3.8.egg/trio_websocket/_impl.py", line 374, in serve_websocket
    await server.run(task_status=task_status)
  File "/usr/lib/python3.8/site-packages/trio_websocket-0.8.0-py3.8.egg/trio_websocket/_impl.py", line 1345, in run
    await trio.sleep_forever()
  File "/usr/lib/python3.8/site-packages/trio/_core/_run.py", line 730, in __aexit__
    raise combined_error_from_nursery
  File "/usr/lib/python3.8/site-packages/trio/_highlevel_serve_listeners.py", line 129, in serve_listeners
    task_status.started(listeners)
  File "/usr/lib/python3.8/site-packages/trio/_core/_run.py", line 730, in __aexit__
    raise combined_error_from_nursery
  File "/usr/lib/python3.8/site-packages/trio/_highlevel_serve_listeners.py", line 27, in _run_handler
    await handler(stream)
  File "/usr/lib/python3.8/site-packages/trio_websocket-0.8.0-py3.8.egg/trio_websocket/_impl.py", line 1373, in _handle_connection
    await connection.aclose()
  File "/usr/lib/python3.8/site-packages/trio/_core/_run.py", line 730, in __aexit__
    raise combined_error_from_nursery
  File "/usr/lib/python3.8/site-packages/trio_websocket-0.8.0-py3.8.egg/trio_websocket/_impl.py", line 1148, in _reader_task
    await handler(event)
  File "/usr/lib/python3.8/site-packages/trio_websocket-0.8.0-py3.8.egg/trio_websocket/_impl.py", line 1071, in _handle_message_event
    await self._send_channel.send(msg)
  File "/usr/lib/python3.8/site-packages/trio/_channel.py", line 174, in send
    await trio.hazmat.wait_task_rescheduled(abort_fn)
  File "/usr/lib/python3.8/site-packages/trio/_core/_traps.py", line 165, in wait_task_rescheduled
    return (await _async_yield(WaitTaskRescheduled(abort_func))).unwrap()
  File "/usr/lib/python3.8/site-packages/outcome/_sync.py", line 111, in unwrap
    raise captured_error
trio.ClosedResourceError

I don't get any errors if I just use websocat and type messages by hand.

versions

~/s/l/p/tests [legimens]× » python --version       
Python 3.8.2

~/s/l/p/tests [legimens]× » pip show trio-websocket                       
Name: trio-websocket
Version: 0.8.0
[...]
~/s/l/p/tests [legimens]× » uname -a    
Linux archlinux 5.5.13-arch2-1 #1 SMP PREEMPT Mon, 30 Mar 2020 20:42:41 +0000 x86_64 GNU/Linux

[nmichaud]

I've been trying to debug this error as well - at first I thought it was my own code, but it seems to be easy to trigger when closing a connection from the client side while the server has a pending write.

[belm0]

I'm blocked from making a bugfix release as I don't have admin access to the PyPI package. I'm trying to resolve it.