Comment by jafffsuds

> There’s no built-in goroutine-style preemption. Long CPU-bound work in an async task starves the executor; you offload to tokio::task::spawn_blocking or rayon instead.

I don't know why anyone uses spawn_blocking for CPU-bound tasks. It's clearly designed for blocking IO tasks. There's a reason why Erlang cordons them separately into Dirty CPU and Dirty IO schedulers.