console

tokio-console

Chat | API Documentation (main branch)

what's all this, then?

this repository contains an implementation of TurboWish/tokio-console, a diagnostics and debugging tool for asynchronous Rust programs. the diagnostic toolkit consists of multiple components:

• a wire protocol for streaming diagnostic data from instrumented applications to diagnostic tools. the wire format is defined using gRPC and protocol buffers, for efficient transport on the wire and interoperability between different implementations of data producers and consumers.

  the console-api crate contains generated code for this wire format for projects using the tonic gRPC implementation. additionally, projects using other gRPC code generators (including those in other languages!) can depend on the protobuf definitions themselves.

• instrumentation for collecting diagnostic data from a process and exposing it over the wire format. the console-subscriber crate in this repository contains an implementation of the instrumentation-side API as a tracing-subscriber Layer, for projects using Tokio and tracing.

• tools for displaying and exploring diagnostic data, implemented as gRPC clients using the console wire protocol. the tokio-console crate implements an an interactive command-line tool that consumes this data, but other implementations, such as graphical or web-based tools, are also possible.

extremely cool and amazing screenshots

wow! whoa! it's like top(1) for tasks!

viewing details for a single task:

on the shoulders of giants

the console is part of a much larger effort to improve debugging tooling for async Rust. a 2019 Google Summer of Code project by Matthias Prechtl (@matprec) implemented an initial prototype, with a focus on interactive log viewing. more recently, both the Tokio team and the async foundations working group have made diagnostics and debugging tools a priority for async Rust in 2021 and beyond. in particular, a series of blog posts by @pnkfelix lay out much of the vision that this project seeks to eventually implement.

furthermore, we're indebted to our antecedents in other programming languages and environments for inspiration. this includes tools and systems such as pprof, Unix top(1) and htop(1), XCode's Instruments, and many others.

using it

instrumenting your program

to instrument an application using Tokio, add a dependency on the console-subscriber crate, and add this one-liner to the top of your main function:

console_subscriber::init();

notes:

• in order to collect task data from Tokio, the tokio_unstable cfg must be enabled. for example, you could build your project with

  RUSTFLAGS="--cfg tokio_unstable" cargo build
  

  or add the following to your .cargo/config.toml file:

  [build]
  rustflags = ["--cfg", "tokio_unstable"]
  

  For more information on the appropriate location of your .cargo/config.toml file, especially when using workspaces, see the console-subscriber readme.

• the tokio and runtime tracing targets must be enabled at the TRACE level.

  • if you're using the console_subscriber::init() or console_subscriber::Builder APIs, these targets are enabled automatically.

  • if you are manually configuring the tracing subscriber using the EnvFilter or Targets filters from tracing-subscriber, add "tokio=trace,runtime=trace" to your filter configuration.

  • also, ensure you have not enabled any of the compile time filter features in your Cargo.toml.

running the console

to run the console command-line tool, install tokio-console from crates.io

cargo install --locked tokio-console

and run locally

tokio-console

alternative method: run the tool from a local checkout of this repository

$ cargo run

by default, this will attempt to connect to an instrumented application running on localhost on port 6669. if the application is running somewhere else, or is serving the console endpoint on a different port, a target address can be passed as an argument to the console (either as an <IP>:<PORT> or <DNS_NAME>:<PORT>). for example:

cargo run -- http://my.great.console.app.local:5555

The console command-line tool supports a number of additional flags to configure its behavior. The help command will print a list of supported command-line flags and arguments:

…

running the console on windows

The console uses the UTF-8 character set to display graphs and other visual features in the terminal. In order to display this rich terminal UI on Windows, it's necessary to use a UTF-8-enabled terminal emulator, such as the new Windows Terminal.

If you're using a terminal that supports UTF-8, make sure to explicitly call tokio-console with the UTF-8 language flag set:

tokio-console --lang en_US.UTF-8

for development

the console-subscriber/examples directory contains some potentially useful tools:

• app.rs: a very simple example program that spawns a bunch of tasks in a loop forever
• dump.rs: a simple CLI program that dumps the data stream from a Tasks server

Examples can be executed with:

cargo run --example $name