A simple tool to gather memory usage when files are required. More info at: http://bitmonkey.net/post/308322913

require_tracking.rb

#
# Created by Eric Lindvall <[email protected]>
#
# WHAT: Provides a simple overview of memory allocation occuring during a
# require.
#
# For a longer explanation, see my post at:
#
# http://bitmonkey.net/post/308322913/tracking-initial-memory-usage-by-file-in-ruby
#
# NOTE: The numbers provided are of self + children, meaning the same will
# be attributed to multiple files at once.
#
# Also, memory that is no longer referenced (and would be freed) is still
# taken into account.
#
# It is intended to give a simple overview of allocations to track down gross
# offenders, not give an exact view of your memory usage.
#

if GC.respond_to?(:enable_stats)
  module RequireTracking
    def require(*args)
      start_allocated_size = GC.allocated_size
      super
    ensure
      $require_stats[args.first] += (GC.allocated_size - start_allocated_size)
    end
    
    def numeric_thousands_indicators(number)
      number.to_s.gsub(/(\d)(?=\d{3}+(?:\.|$))(\d{3}\..*)?/,'\1,\2')
    end
  end

  Object.send(:include, RequireTracking)
  Kernel.send(:include, RequireTracking)
  
  $require_stats       = Hash.new { |h,k| h[k] = 0 }
  $require_stats_top ||= 20
  GC.enable_stats
  GC.clear_stats
  
  at_exit do
    puts "Memory used by file:"
    puts " %40s %s" % [ 'File', 'KB' ]
    puts " %40s %s" % [ '-------------', '--------' ]
    $require_stats.sort_by { |k,v| -v }.slice(0, $require_stats_top).each do |(k,v)|
      puts "%40s: %s" % [ k, numeric_thousands_indicators(v / 1024) ]
    end
  end
else
  puts "Warning: Not running with an interpreter with GC statistics"
end

run.txt

> ruby -rrequire_tracking -e "require 'active_support'"
Memory used by file:
                           File KB
                  ------------- --------
                      rubygems: 5,421
                active_support: 4,296
       active_support/core_ext: 2,361
           active_support/json: 1,161
  active_support/json/encoding: 1,063
          rubygems/config_file: 921
                          yaml: 877
                yaml/rubytypes: 669
                          date: 573
         active_support/vendor: 524
         rubygems/source_index: 490
      rubygems/command_manager: 448
     commands/abstract_command: 446
 rubygems/local_remote_options: 428
                       builder: 407
                           uri: 406
              rubygems/command: 399
             builder/xmlmarkup: 393
                          json: 383
               builder/xmlbase: 346

thanks, added time from gist#140012, http://gist.github.com/465431