Why is there a limit on delayed calls like asyncio.call_later to not exceed one day?

Question

https://docs.python.org/3/library/asyncio-eventloop.html#delayed-calls

Note: Timeouts (relative delay or absolute when) should not exceed one day.

Does anyone have a good explanation as to why this limit exists?

Thanks in advance

Answer 1

This is due to issue 20493:

In asyncio, if the next event is in 2^40 seconds, epoll.poll() raises an OverflowError because epoll_wait() maximum value for the timeout is INT_MAX seconds.

Guido van Rossum suggested that:

For now, can we just add to the asyncio docs that timeouts shouldn't exceed one day? Then we can fix it later without breaking expectations.

It's best to read the full issue log for all details and considerations.