When trying to shutdown a streams based server I often get a "Task was destroyed but it is pending!" error and haven't been able to find a way to fix it.
I've been able to reproduce this using the "TCP echo server using streams" example in the Python docs <https://docs.python.org/3/library/asyncio-stream.html#tcp-echo-server-using-streams> by establishing a connection (nc localhost 8888) and then interrupting the server before sending any data: Python-3.5.0a3$ PYTHONASYNCIODEBUG=1 ./python /tmp/tcp_echo_using_streams.py Serving on ('127.0.0.1', 8888) ^CTask was destroyed but it is pending! source_traceback: Object created at (most recent call last): File "/tmp/tcp_echo_using_streams.py", line 24, in <module> loop.run_forever() File "/home/dcoles/src/Python-3.5.0a3/Lib/asyncio/base_events.py", line 276, in run_forever self._run_once() File "/home/dcoles/src/Python-3.5.0a3/Lib/asyncio/base_events.py", line 1164, in _run_once handle._run() File "/home/dcoles/src/Python-3.5.0a3/Lib/asyncio/events.py", line 120, in _run self._callback(*self._args) File "/home/dcoles/src/Python-3.5.0a3/Lib/asyncio/streams.py", line 227, in connection_made self._loop.create_task(res) task: <Task pending coro=<handle_echo() done, defined at /tmp/tcp_echo_using_streams.py:3> wait_for=<Future pending cb=[Task._wakeup()] created at /home/dcoles/src/Python-3.5.0a3/Lib/asyncio/streams.py:392> created at /home/dcoles/src/Python-3.5.0a3/Lib/asyncio/streams.py:227> It appears that the issue here is that since there is still a connected client socket, Server.close() will leave the connected socket untouched meaning the client_connected_cb task will remain active. PEP-3156 specifically states that Server.wait_closed is "A coroutine that blocks until the service is closed and all accepted requests have been handled", so I'm surprised that wait_closed doesn't block until the connection is closed. Additionally there doesn't seem to be any way of forcing all connections to close (short of adding this logic to the coroutine). Should Server.wait_closed block if there are remaining connections? Is it possible to force these connections closed? Cheers, David
