Contention over mutable state is orthogonal to async/await in Rust. Proof is that they had the contention problem solved prior to async/await. Pure functional l

Contention over mutable state is orthogonal to async/await in Rust. Proof is that they had the contention problem solved prior to async/await. Pure functional languages also solve the contention problem by simply destroying mutable state, without async labelling. A brute force solution, but a solution. async/await doesn't solve the problem of things possibly mutating things when you weren't running; you've turned over the thread of control, if your language permits mutation it can happen without you knowing. Rust solves that in other ways that have nothing to do with async/await, and its solution works with preemptive threading. Rust has been able to thread since long before async/await was introduced. It was introduced because for some of the use cases of Rust the overhead was unacceptable, not because prior to async you had no options at all to have that sort of functionality.