Re:Tokio 1.0 – async runtime for Rust
by slavik81 on Thursday December 24, 2020 @02:29PM
(#25530605)
That does answer my question, but I don't really understand why the distinction is made. To the caller, a function that spends time waiting and a function that spends the same time calculating both look the same, don't they?
Re:Tokio 1.0 – async runtime for Rust
by ubercow13 on Thursday December 24, 2020 @07:40PM
(#25533074)
The difference is that the runtime can schedule something else if the blocking is async. It looks the same as sync blocking to the caller, but not the scheduler. The point of async is you can write code that looks synchronous but is actually participating in cooperative multitasking.
With blocking I mean waiting. For I/O to complete, for time to pass, or for another task to complete something. In event-based programming, functions must not block. Async functions may seem to block, but they don't rely because a state machine is involved.