tokio 1.44.1

Tokio

A runtime for writing reliable, asynchronous, and slim applications withthe Rust programming language. It is:

• Fast: Tokio's zero-cost abstractions give you bare-metalperformance.

• Reliable: Tokio leverages Rust's ownership, type system, andconcurrency model to reduce bugs and ensure thread safety.

• Scalable: Tokio has a minimal footprint, and handles backpressureand cancellation naturally.

Website |Guides |API Docs |Chat

Overview

Tokio is an event-driven, non-blocking I/O platform for writingasynchronous applications with the Rust programming language. At a highlevel, it provides a few major components:

• A multithreaded, work-stealing based taskscheduler.
• A reactor backed by the operating system's event queue (epoll, kqueue,IOCP, etc...).
• AsynchronousTCP and UDP sockets.

These components provide the runtime components necessary for buildingan asynchronous application.

Example

A basic TCP echo server with Tokio.

Make sure you activated the full features of the tokio crate on Cargo.toml:

[dependencies]tokio={version="1.44.1",features=["full"]}

Then, on your main.rs:

usetokio::net::TcpListener;usetokio::io::{AsyncReadExt, AsyncWriteExt};#[tokio::main]asyncfnmain()->Result<(),Box<dynstd::error::Error>>{let listener=TcpListener::bind("127.0.0.1:8080").await?;loop{let(mut socket,_)= listener.accept().await?;tokio::spawn(asyncmove{letmut 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 closedOk(0)=>return,Ok(n)=> n,Err(e)=>{eprintln!("failed to read from socket; err ={:?}", e);return;}};// Write the data backifletErr(e)= socket.write_all(&buf[0..n]).await{eprintln!("failed to write to socket; err ={:?}", e);return;}}});}}

More examples can be foundhere. For a larger "real world" example, see themini-redis repository.

To see a list of the available features flags that can be enabled, check ourdocs.

Getting Help

First, see if the answer to your question can be found in theGuides or theAPI documentation. If the answer is not there, there is an active community intheTokio Discord server. We would be happy to try to answer yourquestion. You can also ask your question onthe discussions page.

Contributing

:balloon: Thanks for your help improving the project! We are so happy to haveyou! We have acontributing guide to help you get involved in the Tokioproject.

Related Projects

In addition to the crates in this repository, the Tokio project also maintainsseveral other libraries, including:

• axum: A web application framework that focuses on ergonomics and modularity.

• hyper: A fast and correct HTTP/1.1 and HTTP/2 implementation for Rust.

• tonic: A gRPC over HTTP/2 implementation focused on high performance, interoperability, and flexibility.

• warp: A super-easy, composable, web server framework for warp speeds.

• tower: A library of modular and reusable components for building robust networking clients and servers.

• tracing (formerlytokio-trace): A framework for application-level tracing and async-aware diagnostics.

• mio: A low-level, cross-platform abstraction over OS I/O APIs that powerstokio.

• bytes: Utilities for working with bytes, including efficient byte buffers.

• loom: A testing tool for concurrent Rust code.

Changelog

The Tokio repository contains multiple crates. Each crate has its own changelog.

• tokio -view changelog
• tokio-util -view changelog
• tokio-stream -view changelog
• tokio-macros -view changelog
• tokio-test -view changelog

Supported Rust Versions

Tokio will keep a rolling MSRV (minimum supported rust version) policy ofatleast 6 months. When increasing the MSRV, the new Rust version must have beenreleased at least six months ago. The current MSRV is 1.70.

Note that the MSRV is not increased automatically, and only as part of a minorrelease. The MSRV history for past minor releases can be found below:

• 1.39 to now - Rust 1.70
• 1.30 to 1.38 - Rust 1.63
• 1.27 to 1.29 - Rust 1.56
• 1.17 to 1.26 - Rust 1.49
• 1.15 to 1.16 - Rust 1.46
• 1.0 to 1.14 - Rust 1.45

Note that although we try to avoid the situation where a dependency transitivelyincreases the MSRV of Tokio, we do not guarantee that this does not happen.However, every minor release will have some set of versions of dependencies thatworks with the MSRV of that minor release.

Release schedule

Tokio doesn't follow a fixed release schedule, but we typically make one minorrelease each month. We make patch releases for bugfixes as necessary.

Bug patching policy

For the purposes of making patch releases with bugfixes, we have designatedcertain minor releases as LTS (long term support) releases. Whenever a bugwarrants a patch release with a fix for the bug, it will be backported andreleased as a new patch release for each LTS minor version. Our current LTSreleases are:

• 1.38.x - LTS release until July 2025. (MSRV 1.63)
• 1.43.x - LTS release until March 2026. (MSRV 1.70)

Each LTS release will continue to receive backported fixes for at least a year.If you wish to use a fixed minor release in your project, we recommend that youuse an LTS release.

To use a fixed minor version, you can specify the version with a tilde. Forexample, to specify that you wish to use the newest1.32.x patch release, youcan use the following dependency specification:

tokio = { version = "~1.38", features = [...] }

Previous LTS releases

• 1.8.x - LTS release until February 2022.
• 1.14.x - LTS release until June 2022.
• 1.18.x - LTS release until June 2023.
• 1.20.x - LTS release until September 2023.
• 1.25.x - LTS release until March 2024.
• 1.32.x - LTS release until September 2024.
• 1.36.x - LTS release until March 2025.

License

This project is licensed under theMIT license.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submittedfor inclusion in Tokio by you, shall be licensed as MIT, without any additionalterms or conditions.