Tokio is a Rust asynchronous runtime and library for building network applications with nonblocking I/O. Rust’s standard library supplies only the essentials for asynchronous execution, so Tokio provides the runtime used to run async programs. Its role becomes especially useful when applications handle many concurrent network, file, or database I/O operations. section 10.2 section 10.3
A small Tokio program combines several Rust asynchronous primitives:
- Declare an asynchronous entry point with #[tokio::main] and async fn main(). section 10.2
- Launch concurrent tasks with tokio::spawn(async { ... }) and wait for them with tokio::join!. section 10.2
- Activate lazy asynchronous functions with .await; calling an async function alone does not execute it. section 10.2
- Understand async functions as producing futures: deferred computations that can be polled until Poll::Ready or remain Poll::Pending. section 10.3
Concurrent file-processing tasks
A binary crate enables Tokio with tokio = { version = "1", features = ["full"] }. The async main function spawns one task for each simulated file read, awaits both reads, and joins their handles. The resulting output processes file 2 before file 1 when their simulated durations differ, demonstrating concurrent asynchronous task execution.
