From: Blackie <mudsweatandears@...>
Date: 2007-10-11T20:35:08+09:00
Subject: Should *most* memory be release back to the system?

If anyone can explain this I would appreciate it.

I have an IT group knocking Ruby saying that it never releases memory
back to the system (to be available to procs other than Ruby) so
feeling somewhat defensive I went and wrote a dumb script that goes
back and forth between two methods, one cat'ing huge strings and the
other parsing an xml doc with Hpricot.

"task" tops off (in top) around 50M and "other_task" peaks around 150M
(on my machine, CentOS, lastest stable 1.8.6) but when we return to
running "task" for extended periods, memory usage remains at ~150M.

Forgive my ignorance. Can anyone explain this behavior or at least
point me to a place to educate myself?

Many thanks, the script I'm running is below.

--------
#!/usr/bin/env ruby
require 'rubygems'
require 'hpricot'

def other_task
  a = []
  9999.times  do
    a << "12345678901234567890123456789012345678901234567890" * 100
  end
  nil
end

def task
  # 500K xml data
  data = File.readlines("very_large_output.xml").to_s
  temp = Hpricot.XML data
  nil
end

puts "In task"
10.times {|i| task; p i}
puts "In other task"
100.times {|i| other_task; p i}
puts "In task (Should memory go down?)"
100.times {|i| task; p i}