[thecompilr]

For me async is about ergonomics first of all. When you perform parallel tasks on multiple threads it is hard and ugly (in cross platform Rust at least) to implement any sort of intricate cross communication, as communication between threads is asynchronous by nature. And it is very much impossible to stop a thread externally.

Async rust lets you implement different combinators on async tasks and cancel them effortlessly.

As for performance, tokio is not exactly a zero cost abstraction. Just run perf on a tokio program to see how big of overhead it introduces. It has claimed to be zero cost from the start, and since then it has done at least two major performance overhauls, to prove the point. That being said I love tokio and its ecosystem, but it is ergonomics, not speed that I love. That being said async-std was much slower for the networking use case that I had, so overall tokio is as good as it gets.

[WindSoldier]

Why do you say async-std is so much slower? If there any result or report shows that? I'm also curious about the `perf` you mentioned.

[thecompilr]

Well, at least it was slower a while ago, for the networking code I was working on. Could be outperforming for other use cases. As for perf, when you run it you can see that a lot of cpu is sent on work stealing and other bookkeeping. Which is fine, and the single threaded runtime doesn’t have some of that, so I use that a lot.