bhanditz / rspec-gc-control

Add a mechanism to control the garbage collector in RSpec.

rspec-gc-control

Summary

This gem extends RSpec to allow you to control how often GC cycles happen in order to trade increased memory usage for faster test runs. It's an encapsulated and reusable version of the code shown in this article:

http://www.rubyinside.com/careful-cutting-to-get-faster-rspec-runs-with-rails-5207.html

Requirements

For this to work, you need a Ruby that supports explicit control over the garbage collector, and RSpec 2.11.1 or higher.

Supported Rubies include MRI 1.9.2 and 1.9.3, and most likely Rubinius.

Unsupported Rubies are:

• MRI 1.8.x: No support for GC.count.
• JRuby: GC.enable / GC.disable are no-ops.

On unsupported platforms, attempting to enable explicit GC control via this plugin will produce a warning and have no other effect.

Installation and Usage

Install the gem:

gem install rspec-gc-control

Or if you're using bundler, add this line to your Gemfile and run bundle install:

gem 'rspec-gc-control'

Once you have the gem installed, edit your spec_helper.rb file to set gc_every_n_examples to an appropriate value. You may want to play with this value while watching memory consumption for the process to get a feeling for how significant a tradeoff you're making in terms of increased memory usage.

RSpec.configure do |c|
  c.gc_every_n_examples = 10
end

You'll know it's working if you see output like the following at the end of your test run:

Finished in 6.45 seconds (including 7 forced GC cycle(s), totalling 0.67116 seconds)
71 examples, 0 failures, 1 pending