gistfile1.rb

#foo.rb
class Foo
end

# bork.rb
require 'rubygems'
require 'active_record'

def bork
  5.times do
    start = Time.now
    
    fork do
      require 'foo.rb'
      puts "Foo is defined in fork" if defined?(Foo)
      if defined?(ActiveRecord::Base)
        puts "ActiveRecord defined in fork. WIN!"
      else
        puts "ActiveRecord not defined in fork. FAIL!"
      end
    end
    
    Process.wait
    
    puts "took #{Time.now-start}s to rejoin parent"
    
    if defined?(Foo)
      puts "Foo is defined in parent after child exists. FAIL!"  
    else
      puts "Foo is not defined in parent after child exists. WIN!"  
    end
  end
end

bork