Python has had async for 10 years – why isn't it more popular?

The truth is that in python, async was too little, too late. By the time it was introduced, most people who actually needed to do lots of io concurrently had their own workarounds (forking, etc) and people who didn't actually need it had found out how to get by without it (multiprocessing etc).

Meanwhile, go showed us what good green threads can look like. Then java did it too. Meanwhile, js had better async support the whole time. But all it did was show us that async code just plain sucks compared to green thread code that can just block, instead of having to do the async dances.

So, why engage with it when you already had good solutions?

I take so much flak for this opinion at work, but I agree with you 100%.

Code that looks synchronous, but is really async, has funny failure modes and idiosyncracies, and I generally see more bugs in the async parts of our code at work.

Maybe I’m just old, but I don’t think it’s worth it. Syntactic sugar over continuations/closures basically..

The comment you are responding to prefers green threads to be managed like goroutines, where the code looks synchronous, but really it's cooperative multitasking managed by the runtime, to explicit async/await.

But then you criticize "code that looks synchronous but is really async". So you prefer the explicit "async" keywords? What exactly is your preferred model here?

Goroutines feel like old-school, threaded code to me. I spawn a goroutine and interact with other “threads” through well defined IPC. I can’t tell if I’m spawning a green thread or a “real” system thread.

C#’s async/await is different IMO and I prefer the other model. I think the async-concept gets overused (at my workplace at least).

If you know Haskell, I would compare it to overuse of laziness, when strictness would likely use fewer resources and be much easier to reason about. I see many of the same problems/bugs with async/await..

Problem is it that it self reinforces and before you look every little function is suddenly async.

The irony is that it is used where you want to write in a synchronous style...