Rails 3 - Speed up Console Loading Time

I finally found my startup bottlenecks using Benchmark. In particular, navigate to the bundler gem and in lib/bundler/runtime.rb, find the line that does Kernel.require and wrap it like this:

puts Benchmark.measure("require #{file}") {  Kernel.require file}.format("%n: %t %r")

You may have to add require 'benchmark' somewhere in your app, like in config/boot.rb. That will show you how long it takes to require each gem. I can't guarantee your results will match mine, but I had a few gems that were taking over a second to load compared with sub-millisecond for most. A few were gems that I didn't need for developing but I did need for some tasks in the development environment, e.g. capistrano, shoulda. I benchmarked other areas of startup (initializers, etc), but couldn't find any significant bottlenecks.

I haven't yet figured out a clean way to configure the app to only load those for tasks where they are really needed. Possibly, I could create an environment called :speedy and use RAILS_ENV=speedy rails s/c for startup when I know I don't need those gems. Then in Gemfile, I could use group :speedy to exclude those gems in certain cases.

All that said, the biggest startup annoyance for me is having to load the entire environment to run a rake task. I could probably exclude most gems for that, but Gemfile would start to get messy so I don't know if it's worth it.

Slightly adapted form that is copy-pastable, wraps all requires, and provides sortable output:

# Add this to the top of boot.rbrequire 'benchmark'def require(file)  puts Benchmark.measure("") {    super  }.format("%t require #{file}")end

Then you can execute no-op to see them:

rails runner 1

Or sort them and show the top 50:

rails runner 1 | sort -nr | head -n 50

You can speed it up by adding :require => nil to the slow Gemfile entries and require them manually.e.g.

gem 'jammit', :require => nil

I also addressed this issue in a meetup i've had.This seems to be a bug in ruby 1.9.2 (see comments of this patch: https://gist.github.com/1008945)

You can fix it by patching your 1.9.2 by the gist i just linked or upgrading to 1.9.2-head or 1.9.3-head.