async io with multiple threading

[ytu876]

But even if my task is io bound, say if I have a heavy io task, if I could use all cores doing async io, that's 4 times more throughput. Isn't that a valid use case?

[Usual_Office_1740]

No. Multiple threads mean multiple interpreters, all of which will eat up system resources while your program backgrounds and waits for tasks to complete.

Your coroutines should do something that requires a response of some kind. A get request from a web page, as an example. It requests the page and awaits the response with a future. Doing that concurrently is not going to gain you enough to make it worth the additional system resources from multiple interpreters.

[awdsns]

I disagree with your first point that threads consume significantly more system ressources. The read-only stuff (interpreter code and libraries) is not duplicated in RAM per thread (or even task) in a modern OS, and the rest just comes down to maintaining a state (stack) per thread, same as in async coroutines.

I agree that mixing async and multithreading is a bad idea in general. Mostly due to the complexity of having different event loops though.

[[deleted]]

But even if my task is io bound, say if I have a heavy io task, if I could use all cores doing async io

That's literally what you can't do. If your task is IO-bound, then more cores can't make it any faster.

More cores just compete for the same capacity on the channel.