Debuggin Ruby

debugging.rb

GC.enable_stats if defined?(GC) && GC.respond_to?(:enable_stats)
GC.start # clean up heap
# dump it, including class names of heap objects
GC.dump_file_and_line_info(filename: "heap.dump", include_class_names: true)

stat_string = "allocated: #{GC.allocated_size/1024}K total in #{GC.num_allocations} allocations, GC calls: #{GC.collections}, GC time: #{GC.time / 1000} msec"

shell

rvm get stable
find $rvm_path/patch* -type f   # See all your patches
rvm install 1.9.3 --patch railsexpress -C --enable-gcdebug -n gcdebug

statistics.rb

def get_object_stats
  return_value = Hash.new
  ObjectSpace::each_object(Object) {|my_object|
    unless return_value[my_object.class.to_s.downcase].nil?
      return_value[my_object.class.to_s.downcase][:count] += 1
    else
      return_value[my_object.class.to_s.downcase] = Hash.new
      return_value[my_object.class.to_s.downcase][:name] = my_object.class
      return_value[my_object.class.to_s.downcase][:count] = 1
    end
  }
  return_value.sort_by {|k,v| -v[:count]}
end

Another useful patch:
rvm install 1.9.3 --with-gcc=gcc --patch gcdata -n gcdata