can the use of threads + async + cachetools lead to an "event loop closed" error?

[flixman]

This is not a bug but a question. I have an async Flask application that runs through gunicorn, with 1 worker and 4 threads. In one of the endpoints, which am caching with the asyncache cached decorator, I am doing an async call to another service. Many times I get back an "event loop closed" error. Is this to be expected? A sample of my code is:

from asyncache import cached
from cachetools import TTLCache

@cached(TTLCache(maxsize=32, ttl=60))
async def _retrieve_container_folders(account, aio_cred, container):
  return await call_to_async_method()

I have coded a thread-safe version of the TTLCache, like this

import threading

from cachetools import TTLCache as TTLCacheUpstream

_lock = threading.Lock()


class TTLCache(TTLCacheUpstream):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    def __getitem__(self, *args, **kwargs):
        with _lock:
            return super().__getitem__(*args, **kwargs)

    def __setitem__(self, *args, **kwargs):
        with _lock:
            return super().__setitem__(*args, **kwargs)

But this, sometimes, just returns an empty result, so... I am pretty lost, here...

[tkem]

This looks more like a question regarding asyncache, which is a separate project.