I’m now convinced that the bug we’re fixing and the original bug with debug mode off are two separate bugs. With the fix in place and debug mode off, I’m still seeing the original buggy behavior. Bummer.


In my actual program, I have an async generator that spawns two tasks. In the finally clause I cancel and wait for them, then check and log any exceptions. The program ran on Python 3.7. The symptom of the original bug is occasional “Task exception was never retrieved” log entries about one of the spawned tasks. After I patched 3.7 with the fix, the symptom remains, so the fix does not actually fix the original bug.

Running the same program on master, there are additional error and warning messages about open stream objects being garbage collected, unclosed sockets, etc. Are these logging messages new to 3.8? If not, perhaps 3.8 introduced additional bugs?