Top ten instantiated classes by instance count on Ruby 1.9.3 startup (MRI)

top_ten_instantiated_classes.rb

classes = Hash.new(0)
ObjectSpace.each_object do |object|
  classes[object.class] += 1
end

top_ten = classes.values.uniq.sort.reverse[9]
classes.select {|_, c| c >= top_ten}.sort_by {|_, c| -c}.each do |klass, c|
  puts "#{klass}: #{c}"
end

__END__
String: 5037
Array: 328
Class: 205
RubyVM::InstructionSequence: 198
MatchData: 108
Encoding: 99
RubyVM::Env: 37
Proc: 35
Regexp: 24
Module: 21