It appears that the alru_cache decorator is using an unsynchronized OrderedDict instance for its cache:

If I am not mistaken, that will lead to a data race if the decorated function is called simultaneously from different asyncio event loops running on different threads — which seems to be a realistic (if rare) situation (compare python/cpython#93462 (comment)).

If I understand correctly, other asyncio wrappers generally bind the event loop during initialization and fail explicitly if called from a different event loop. Unfortunately, since the alru_cache decorator generally runs at module init time there is no such loop on the thread.

I don't have a clear idea of how this problem could be fixed; I just wanted to point it out as a (significant and subtle) risk for users of this module.