A few simple checks to make sure we are not regressing into slow boot times by preloading to many things. Needs to be the last initializer so it catches what all the others are doing -> zz.rb
Code
# config/initializers/zz.rb
if Rails.env.development?
# make sure we do not regress into slow startup time by preloading to much
Rails.configuration.after_initialize do
[
ActiveRecord::Base.send(:descendants).map(&:name),
ActionController::Base.descendants.map(&:name),
(File.basename($0) != "rake" && defined?(Rake) && "rake"),
].compact.flatten.each { |c| raise "#{c} should not be loaded" }
end
end
Result
config/initializers/zz.rb:9:in `block (2 levels) in ': User should not be loaded (RuntimeError)
Michael Grosser, the Blog 