Async/Await is finally back in Zig

I often write Rust and I don't find it very attractive, but so many good projects seem to advertise it as a "killer feature". Diesel.rs doesn't have async, and they claim that perf improvement may not be worth it (https://users.rust-lang.org/t/why-use-diesel-when-its-not-as...).

For a single threaded JS program, async makes a lot of sense. I can't imagine any alternative pattern to get concurrency so cleanly.

Because when you require 1 thread per 1 connection, you have trouble getting to thousands of active connections and people want to scale way beyond that. System threads have overhead that makes them impractical for this use case. The alternatives are callbacks, which everybody hates and for a good reason. Then you have callbacks wrapped by Futures/Promises. And then you have some form of coroutines.

Keeping in mind that what Zig is introducing is not what languages call async/await. It's more like the I/O abstraction inside Java, where you can use the same APIs with platform threads and virtual threads, but in Zig, you will need to pass the io parameter around, in Java, it's done in the background.

The event loop model is arguably equivalent to coroutines. Just replace yield with return and have the underlying runtime decide which functions to call next by looping through them in a list. You can even stall the event loop and increase latency if you take too long to return. It's cooperative multitasking by another name.