In this stream, we peeled back the crust on the tokio crate — https://github.com/tokio-rs/tokio/ — and explored its interface, structure, and mechanisms. We talked about blocking, cancellation, spawning, and mechanisms for synchronization. We also dug into some of what goes on under the hood where that ends up being relevant to you as an application author!

For more details about tokio, see https://docs.rs/tokio/.

Discord: https://discord.jonhoo.eu

0:00:00 Introduction
0:02:28 The parts of tokio
0:05:19 The tokio runtime
0:29:08 Blocking
0:48:09 Send bounds and LocalSet
0:51:04 tokio vs std Mutex
0:56:53 Runtime questions
1:06:00 tokio resources
1:28:19 tokio::fs nuances
1:33:47 tokio::process nuances
1:36:27 tokio::io things
1:47:30 tokio-stream
1:56:13 tokio::sync
2:11:10 tokio::task::JoinSet
2:19:13 tokio::select! and cancellation
2:51:26 tokio-util and CancellationToken
3:03:35 common errors: tokio::spawn
3:07:25 common errors: concurrency vs parallelism
3:08:53 common errors: mpsc fan-in
3:12:08 Follow-up questions and outro

Live version with chat: https://youtube.com/live/YlTyZvpaywQ

Jon Gjengset

A deep-dive walkthrough of the Tokio async runtime for Rust, covering how it executes futures, the multi-threaded vs current-thread schedulers, work stealing, blocking (spawn_blocking vs block_in_place), shutdown behavior, local sets for non-Send futures, and the differences between Tokio and standard library mutexes. Practical guidance is given on avoiding blocking worker threads, understanding task vs future distinctions, and using tools like Tokio Console to diagnose runtime issues.

Decrusting the tokio crate