Concurrency in Rust

For a long time, it has not made sense to perform all tasks sequentially in a computer. Of course, sometimes you need to perform some tasks before others, but in most real-world applications, you will want to run some tasks in parallel.

You might, for example, want to respond to HTTP requests. If you do one after the other, the overall server will be slow. Especially when you get many requests per second and some of them take time to complete. You probably want to start responding to others before you finish with the current one.

Furthermore, we now have multiple processors in almost any computer or server, even in most mobile phones. This means that not only can we process other tasks in parallel while our main task is idle, we can really use one processor for each task by using threads. This is a feature that we must use to our advantage when developing high-performance applications.

The main issue with concurrency is that it's hard. We are not used to thinking in parallel...