gistfile1.txt

~/projects/jruby ➔ jirb
irb(main):001:0> require 'java'
=> true
irb(main):002:0> import com.sun.tools.attach.VirtualMachine
=> Java::ComSunToolsAttach::VirtualMachine
irb(main):003:0> vm = VirtualMachine.attach($$.to_s)
=> sun.tools.attach.MacosxAttachProvider@47875da7: 3294
irb(main):004:0> histo = vm.heap_histo([].to_java).to_io
=> #<IO:0x32b95f72>
irb(main):005:0> histo.lines.first(25).each {|line| puts line}; nil

 num     #instances         #bytes  class name
----------------------------------------------
   1:         31678        4668744  <constMethodKlass>
   2:         31678        3811744  <methodKlass>
   3:          3708        3235168  <instanceKlassKlass>
   4:          3708        3190600  <constantPoolKlass>
   5:         46591        2367272  <symbolKlass>
   6:          3560        2015392  <constantPoolCacheKlass>
   7:          8435         779744  [B
   8:         11052         756256  [C
   9:          3966         729744  java.lang.Class
  10:          4936         629872  [S
  11:         11433         457320  java.lang.String
  12:          5010         448448  [[I
  13:          6759         324432  java.util.concurrent.ConcurrentHashMap$HashEntry
  14:          2101         319352  java.lang.reflect.Method
  15:          5909         283632  java.util.HashMap$Entry
  16:          4240         253776  [Ljava.lang.Object;
  17:          2934         211248  org.jruby.runtime.ObjectSpace$WeakReferenceListNode
  18:           321         210552  <methodDataKlass>
  19:          2482         156768  [I
  20:           567         155360  [Ljava.util.HashMap$Entry;
  21:          3463         138520  java.util.ArrayList
  22:           229         131904  <objArrayKlassKlass>
=> nil
irb(main):006:0>