Nelson Minar added the comment:
Doing some more testing, I noticed that if I ask multiprocessing to also log,
the problem stops occurring. If I configure multiprocessing.log_to_stderr()
instead, the error still occurs.
Here's how I configured multiprocessing logging that makes the problem go
New submission from Nelson Minar:
I have a demonstration of a problem where the combination of multiprocessing
with maxtasksperchild=1 and the Python logging library causes tasks to
occasionally get lost. The bug might be related to issue 22393 or issue 6721,
but I'm not certain. issue 10037
