From: Hugh Sasse <hgs@...>
Date: 2007-10-03T22:54:33+09:00
Subject: Re: gc.c -- possible logic error?

On Wed, 3 Oct 2007, Hugh Sasse wrote:

> On Wed, 3 Oct 2007, Eric Hodel wrote:
> 
> > It is also here:
> > 
> > http://rubyforge.org/frs/download.php/12818/mem_inspect-1.0.0.gem
> > 
> For anyone else about to try this:
        [...]
> All the routes through the ruby_mem_inspect_build script assume cvs.
> I've enough information to work around that, I think.

OK, I've managed that.  The results could do with some interpretation.

http://www.eng.cse.dmu.ac.uk/~hgs/ruby/memory_map.18681.1191417911.png

that is for:

http://www.eng.cse.dmu.ac.uk/~hgs/ruby/hashes_read_yaml.rb

leaving it to finish its sleep.

My modified ruby_mem_inspect_build is:
<quote>
#!/scratch/hgs/local/bin/ruby -w
##!/usr/local/bin/ruby -w

require 'rubygems'
require 'rake'

# ruby_dir = "mem_inspect_ruby_1_8"
ruby_dir = "/scratch/hgs/ruby-1.8.6-p110"
old_pwd = Dir.pwd
CVS = false
SVN = false
# PREFIX = "/usr/local"
PREFIX = "/scratch/hgs/local"

# Sun's patch and make are usually not up to snuff. Set these as 
# apppropriate.   (Ruby could do with something to search ENV['PATH'])
MAKE = "gmake"
PATCH = "gpatch"

if File.exist? ruby_dir then
  Dir.chdir ruby_dir do 
    "sh cvs up" if CVS
  end
else
  sh "cvs -z4 -d :pserver:anonymous@cvs.ruby-lang.org:/src co -d #{ruby_dir} -r ruby_1_8 ruby" if CVS
end

Dir.chdir ruby_dir do
  if CVS
    # Why delete and update if we have just got it?
    sh "rm gc.c"
    sh "cvs up gc.c"
  end
  sh "#{PATCH} < #{File.join old_pwd, "gc.c.patch"}"
  sh "autoconf" unless File.exist? "configure"
  sh "./configure --prefix=#{PREFIX} --program-suffix=_mem_inspect" unless File.exist? "Makefile"
  sh MAKE

  puts "*" * 80
  puts "Ruby has been built in #{ruby_dir}, but not installed"
  puts
  puts "If you run:"
  puts
  puts "\tcd #{ruby_dir}; sudo #{MAKE} install"
  puts
  puts "YOU WILL OVERWRITE YOUR STDLIB"
  puts
  puts "Generally, this is harmless, but you may not want that."
  puts "So I'll let you do that all by yourself."
  puts
  puts "You may now run ruby_mem_dump using the patched ruby:"
  puts
  puts "\t#{File.join ruby_dir, "ruby_mem_inspect"} -S ruby_mem_dump"
  puts
  puts "If you haven't installed mem_inspect:"
  puts
  puts "\t#{File.join ruby_dir, "ruby_mem_inspect"} -Ilib bin/ruby_mem_dump"
  puts
  puts "*" * 80
end

</quote>


I don't think I can take this any further, alas: I don't know how to get
meaningful data about which parts of the code create what in memory, how
to find which points of the memory map are salient, and how to extract
how these things change with time.

        Thank you,
        Hugh