For anyone not familiar with http://dev.rubyonrails.org/ticket/6730, I will tell you a story…. (p.s.: ticket was set to invalid, but explains very well the problem I was having)

I had this beautiful class written in a file on the /lib directory of my rails directory. That class stored some data in class variable. Something like this:

# /lib/nice_class.rb
class NiceClass
mattr_accessor :value
end

# /config/environment.rb
NiceClass.value= "Hi there"  # << NiceClass auto-loaded by rails

Ok what happened is that in first request, the value was right, and if I displayed that value in a view, it showed me the message. On second request, I loosed the message! That was because of rails loading the class in every request. That didn’t happened on production mode.

Solution: In the class file, I put:

# Avoid rails loading this file in every request (in dev mode)
unless Dependencies.load_once_paths.include? __FILE__
Dependencies.load_once_paths << __FILE__
end