Question about join() in _parse method and ACME client behavior

[lmarte78]

Hi,

I was looking at the _parse method in challenge.py and noticed that you use ThreadWithReturnValue combined with join() to validate the challenge:

twrv.start()
_validation = twrv.join(timeout=self.challenge_validation_timeout)

According to the ACME protocol (RFC 8555), the server is expected to perform challenge validation in the background, while clients should poll the challenge endpoint to check its status.

I’m curious if the use of join() here is intentional to force synchronous validation, or if it’s a design choice. Would it be safe to remove the join() and let the validation run fully in background, while relying on clients to poll the challenge status as the protocol suggests?

Thanks in advance for any clarification!

[grindsa]

Hi,

The current implementation is more of a design choice, and honestly, it has been bothering me for a while. I’m in the process of refactoring the challenge subsystem, and one of my key goals is to implement a truly asynchronous challenge validation.

That said, I foresee potential issues such as race conditions when accessing the SQLite database, since it doesn’t support parallel connections.

For now, I recommend keeping join() in place and waiting until the refactoring is complete.

/GrindSa