aiopg: connection.cancel can hang

we noticed this callstack in our prod server which hung our main thread breaking the server:

Jul 30 16:48:45.114            File "/usr/local/lib/python3.6/asyncio/base_events.py", line 422 in run_forever
Jul 30 16:48:45.114            File "/usr/local/lib/python3.6/asyncio/base_events.py", line 1434 in _run_once
Jul 30 16:48:45.114            File "/usr/local/lib/python3.6/asyncio/events.py", line 145 in _run
Jul 30 16:48:45.114            File "/usr/local/lib/python3.6/site-packages/aiopg/connection.py", line 226 in cancel

suggest loop.run_in_executor’ing it as supposedly this method is thread safe. Ideally there would be a timeout that affects this as well. I’m not sure if the DSN connect_timeout applies