From: Michal Babej <calcifer@...>
Date: 2009-02-21T18:56:16+09:00
Subject: [ruby-core:22306] Re: [Bug #744] memory leak in callcc?

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Hi,

On Friday 20 of February 2009 23:14:13 Roger Pack wrote:
> The moon is in a good phase. LOL.
> It does seem more stable using the latest version.  I will report back
> if the errors occur more.
Turns out, good moon phases end right after writing a positive feedback emails 
:) Feb 15 ruby-mbari runs the full test suite with same errors as unpatched 
ruby on my machine, but it still segfaults on some certain tests.  E.g. 
running "test/runner.rb net" in row quickly results in segfault.

P.S. i wrote a small script to see how ruby works with fork's copy-on-write 
mechanism. It allocates an array of 1 mil float, then forks, and in the child 
starts rewriting the array in batches (batch size is ARGV[0]). It gives 
completely different results for mbari ruby, and i'd be glad if someone could 
explain why :)

-- Michal


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#!/usr/bin/env ruby

WRITE_BATCH_SIZE=ARGV[0].to_i
unless WRITE_BATCH_SIZE>0
  puts "Usage: #{$0} WRITE_BATCH_SIZE"
  exit 1
end
#GC.disable
puts "\n*** memory used before allocating array: ***"
system('/bin/sh','-c',"cat /proc/#{Process.pid}/status | grep VmRSS")

array = (1..1_000_000).map { rand }

puts "\n*** memory used after allocation: ***"
system('/bin/sh','-c',"cat /proc/#{Process.pid}/status | grep VmRSS")
puts "\n\n\n"
puts "\n*** free memory before fork: ***"
system('/bin/sh','-c','free | grep buffers')


#GC.disable
pid = fork
if pid
  Process.wait(pid)
else
  puts "\n*** free memory after fork: ***"
  system('/bin/sh','-c','free | grep buffers')
  # just to show RSS doesn't change and does *not* reflect real memory usage in this case
  puts "\n*** child's VmRSS before any change: ***"
  system('/bin/sh','-c',"cat /proc/#{Process.pid}/status | grep VmRSS")
  puts "\n\n\n"

  write_start = 0
  10.times do
    sleep 2
    puts "writing.."
    WRITE_BATCH_SIZE.times { |i|
        array[write_start + i]=rand
    }
    write_start += WRITE_BATCH_SIZE
    puts 'done.'
    puts "*** memory state after rewriting #{WRITE_BATCH_SIZE} floats of array: ***"
    system('/bin/sh','-c',"cat /proc/#{Process.pid}/status | grep VmRSS")
    system('/bin/sh','-c','free | grep buffers')
    puts "\n"
  end
end


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