Comment by rtpg

Well for example, lots of queueing libraries have an "eager task" runtime option. What does that do? Instead of putting work into a backend queue, it just immediately runs the task in-process. You don't need any processing queue!

How many times have you shipped some background task change, only to realize half your test suite doesn't do anything with background tasks, and you're not testing your business logic to the logical conclusion? Eager task execution catches bugs earlier on, and is close enough to the reality for things that matter, while removing the need for, say, multi-process cordination in most tests.

And you can still test things the "real way" if you need to!

And to your other point: you can use Dramatiq with Postgres, for example[0]. I've written custom backends that just use pg for these libs, it's usually straightforward because the broker classes tend to abstract the gnarly things.

[0]: https://pypi.org/project/dramatiq-pg/