Zeus preloads your Rails app so that your normal development tasks such as
generate, and specs/tests take less than one second.
This screencast gives a quick overview of how to use zeus with Rails.
Zeus is also covered in RailsCasts episode 412
More technically speaking, Zeus is a language-agnostic application checkpointer for non-multithreaded applications. Currently only ruby is targeted, but explicit support for other languages is on the horizon.
Requirements (for use with Rails)
- OS X 10.7+ OR Linux 2.6.13+
- Rails 3.x
- Ruby 1.9.3+ with backported GC from Ruby 2.0 OR Rubinius
You can install the GC-patched ruby from this gist for rbenv or this gist for RVM. This is not actually 100% necessary, especially if you have a lot of memory. Feel free to give it a shot first without, but if you're suddenly out of RAM, switching to the GC-patched ruby will fix it.
Please note: Zeus requires your project to be running on a file system that supports FSEvents or inotify.
Install the gem.
gem install zeus
Q: "I should put it in my
A: No. You can, but running
bundle exec zeus instead of
zeus adds precious seconds to commands that otherwise would be quite a bit faster. Zeus was built to be run from outside of bundler.
Start the server:
The server will print a list of available commands.
Run some commands in another shell:
zeus console zeus server zeus test test/unit/widget_test.rb zeus test spec/widget_spec.rb zeus generate model omg zeus rake -T zeus runner omg.rb
- Spork - a DRb server that forks before each run to ensure a clean testing state
- Commands - a persistent console that runs Rails commands without reloading the env
- Spring - like Zeus but in pure Ruby, totally automatic, alpha and limited compatibility
If you're switching from Spork, be sure to read the wiki page on Spork.
To add/modify commands, see
To get started hacking on Zeus itself, see
See also the handy contribution guide at
The default plan bundled with zeus only supports Rails 3.x. There is a project (currently WIP) to provide Rails 2.3 support at https://github.com/tyler-smith/zeus-rails23.