From Futures to Runtimes: How Async Rust Actually...

Introduction to Asynchronous Programming In synchronous programming, tasks execute linearly one after another on a single thread. fn synchronous() { println!("1st"); println!("2nd"); println!("3rd"); } For many situations this works great, but if a single task in the chain is slow the entire program halts as we wait for it to finish. This is called "blocking" the thread. use std::time::Duration::from_secs; use std::thread::sleep; fn synchronous_blocking() { println!("1st"); sleep(from_secs(3));