Singleton with eager initialization

I have class X that takes much time to initialize itself. I want to make that class singleton and force its creation when rails application starts.

I've made the singl开发者_高级运维eton:

class X
  @@instance = nil

  def self.instance
    if @@instance.nil?
      @@instance = X.new
      puts 'CREATING'
    end

    return @@instance
  end

  private_class_method :new
end

The problem is that every time I use this class I see 'CREATING' in logs. I've tried to put creation of class in initializers directory but it doesn't work either.

---

The problem was that Rails in development environment doesn't cache classes and application code is reloaded every request.