The docs are surprisingly unspecific for such a mature project, enough that you often need to read source code to confirm your suspicions one way or another. The style has been redone a few different times now, and most of the old stuff is there for backwards compatibility so it's unclear what The Correct Way is to use it (once you step outside the obvious classes and methods).

The source code is like an Escher drawing, I'm sure it makes sense to the maintainer but its logic is incredibly abstract and scattered. From my notes on it ~1 year ago: "I took a dive into Celery source to better understand their native way for inspecting workers... holy shit. Celery is an overgrown jungle of abstractions."

It's honestly kind of surprising to me that Celery is still the undisputed #1 message queue abstraction library. I guess it's a simple enough problem that companies using Python at scale roll their own. I wonder what Instagram uses instead of Celery.

I found this [1] to be a useful comparison between queues in Python, if anybody has found a similarly-terse and exhaustive one that's more up to date for 2024 I'd love to see it.

[1]: https://dramatiq.io/motivation.html

Its powerful but good luck reading the source. Its a bit of a tangled over-engineered mess at this point and the reason there are a number of "newer" libraries to try and replace it. I could not recall specifics since it has been maybe a decade since I last used it but it works until it does not and then its incredibly hard to debug.

Its been a decade and maybe its gotten better but that sentiment is why a number of people do not want to use celery. I would also add that it was created in a different mindset of delayed job and I believe there are better patterns these days without as much complexity.

curious as well!