What problem it solves

Writing asynchronous applications requires runtime components for scheduling tasks, reacting to I/O events, and handling network communication without blocking threads. Tokio provides these components for Rust so applications can coordinate concurrent I/O through an event-driven, non-blocking platform.

Key features

• Task scheduling — The runtime includes a multithreaded, work-stealing task scheduler for distributing asynchronous work.

  Source: README, tokio

• Event-driven I/O — A reactor connects asynchronous applications to operating system event queues such as epoll, kqueue, and IOCP.

  Source: README, tokio

• Asynchronous networking — The platform provides asynchronous TCP and UDP sockets for network communication.

  Source: README, tokio

• Rust concurrency foundations — Tokio uses Rust's ownership, type system, and concurrency model to support thread safety and reduce bugs.

  Source: README, tokio

• Workspace of companion crates — The workspace includes stream, utility, macro, and testing crates alongside the main runtime crate.

  Source: README, tokio-macros, tokio-stream

Quick start

Copied verbatim from the project's README.

[dependencies]
tokio = { version = "1.54.1", features = ["full"] }

use tokio::net::TcpListener;
use tokio::io::{AsyncReadExt, AsyncWriteExt};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let listener = TcpListener::bind("127.0.0.1:8080").await?;

    loop {
        let (mut socket, _) = listener.accept().await?;

        tokio::spawn(async move {
            let mut buf = [0; 1024];

            // In a loop, read data from the socket and write the data back.
            loop {
                let n = match socket.read(&mut buf).await {
                    // socket closed
                    Ok(0) => return,
                    Ok(n) => n,
                    Err(e) => {
                        eprintln!("failed to read from socket; err = {:?}", e);
                        return;
                    }
                };

                // Write the data back
                if let Err(e) = socket.write_all(&buf[0..n]).await {
                    eprintln!("failed to write to socket; err = {:?}", e);
                    return;
                }
            }
        });
    }
}

Who it may suit

This may suit Rust developers building network services, concurrent I/O applications, or other programs that need an asynchronous runtime.

Topics to discuss

• Which runtime configuration and feature-flag combinations are most useful for common application patterns?

• How can developers structure larger asynchronous applications while using Tokio's scheduler and networking components?

• What examples, diagnostics, or testing practices would help newcomers understand asynchronous Rust applications?

Written by ReadmeX AI from the project's README, source and public GitHub data; it may contain mistakes.

Read the original README https://github.com/tokio-rs/tokio#readme

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