How expensive is async/await thread support?

Question

.NET

How expensive is thread support in asynchronous programming?

Answer 1

1. async/await has nothing to do with threads
2. Depends on runtime settings and code written. Somewhere it can be almost free, somewhere expensive. Somewhere there is a lot of benefit, and somewhere there is no benefit.
3. Regarding fully synchronous code, there is a memory overhead for an asynchronous state machine + a CPU and memory overhead for machine operation.
But you do not need to allocate a whole thread to wait for IO