mio 0.5.1

Lightweight non-blocking IO

MIO - Metal IO

MIO is a lightweight IO library for Rust with a focus on adding as little overhead as possible over the OS abstractions.

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Getting started guide

Currently a work in progress: Getting Started. Feedback can be posted on the PR.

API documentation


To use mio, first add this to your Cargo.toml:

mio = "0.5"

Then, add this to your crate root:

extern crate mio;


  • Event loop backed by epoll, kqueue.
  • Zero allocations at runtime
  • Non-blocking TCP, UDP and Unix domain sockets
  • High performance timer system
  • Thread safe message channel for cross thread communication

Non goals

The following are specifically omitted from MIO and are left to the user or higher level libraries.

  • File operations
  • Thread pools / multi-threaded event loop


Currently supported platforms:

  • Linux
  • OS X
  • Windows
  • Android
  • NetBSD

There are potentially others. If you find that Mio works on another platform, submit a PR to update the list!


Please submit PRs containing links to MIO resources.


  • Eventual IO - Proof of concept TCP library built on top of Mio and Eventual's futures & streams.
  • mioco - Mio COroutines
  • simplesched - Coroutine I/O with a simple scheduler
  • coio-rs - Coroutine I/O with work-stealing scheduler
  • rotor - A wrapper that allows to create composable I/O libraries on top of mio
  • ws-rs - WebSockets based on Mio


A group of mio users hang out in the #mio channel on the Mozilla IRC server (irc.mozilla.org). This can be a good place to go for questions.


Interested in getting involved? We would love to help you! For simple bug fixes, just submit a PR with the fix and we can discuss the fix directly in the PR. If the fix is more complex, start with an issue.

If you want to propose an API change, create an issue to start a discussion with the community. Also, feel free to talk with us in the IRC channel.

Finally, be kind. We support the Rust Code of Conduct.