Zeus preloads your Rails app so that your normal development tasks such as console, server, 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.
- OS X 10.7+ OR Linux 2.6.13+
- Rails 3.x
- Compatible Ruby installation
- Ruby 1.9.3+ with backported GC from Ruby 2.0 (rbenv instructions, rvm instructions)
- Ruby 2.0
- Rubinius
For Ruby 1.9.3+, GC patches are 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 Gemfile, right?"
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.
It is common to see tests running twice when starting out with Zeus. If you see your tests/specs running twice, you should try disabling require 'rspec/autotest' and require 'rspec/autorun' (for RSpec), or require 'minitest/autorun' (for Minitest). (see #134 for more information).
Start the server:
zeus start
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
You need to restart zeus if you make changes to various initialization files. Examples of these files include:
- FactoryGirl factories
- RSpec support files
- 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 docs/ruby/modifying.md.
To get started hacking on Zeus itself, see docs/overview.md.
See also the handy contribution guide at contributing.md.
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.