From: Jeremy Hinegardner <jeremy@...>
Date: 2005-11-08T16:54:42+09:00
Subject: OpenBSD AMD64 NoMemoryError - bug ?

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Hi all,

I'm encountering an odd error, but only on the amd64 using OpenBSD. I
believe I've boiled it down to the attached test case.  Here's an
example run on 2 systems I have:

First on CentOS 4.2 x86 with 1GB of RAM:

    $ ./obsd-amd64-membug.rb 
    Allocating a big array of strings of length 300. 
    We've done enough:
        Array size            = 1789570
        Estimated memory size = ruby + 512.00008392334 MB

Good, it does the right thing.  Next on AMD64 OpenBSD 3.7 with 1GB of RAM:

    % ./obsd-amd64-membug.rb 
    Allocating a big array of strings of length 300.
    Caught exception
            Array size            = 126103
    [FATAL] failed to allocate memory

Hmm... odd it failed to allocate memory on a 'puts'.  Very strange. Now
if we alter the script slightly, just remove the '\t' from lines 27 and 28 
in the rescue block we get:

   % ./obsd-amd64-membug.rb 
   Allocating a big array of strings of length 300.
   Caught exception
   Array size            = 126103
   Estimated memory size = ruby + 36.0783576965332 MB

   ./obsd-amd64-membug.rb:13:in `initialize_copy'
   ./obsd-amd64-membug.rb:13
    1) Caught exception failed to allocate memory
    2) Caught exception NoMemoryError
     
I seemed to remember several times in the past year where there have
been whitespace issues in a script that caused odd bugs, but I was
unable to find them.

Anyone have a clue?

enjoy,

-jeremy

-- 
========================================================================
 Jeremy Hinegardner                              jeremy@hinegardner.org 


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#!/usr/local/bin/ruby 

MULTIPLIER = 10
MAX_ALLOC  = 1024 * 1024 * 512 # 512MB

msg = "This is some ruby data (#####)"  * MULTIPLIER
max_msg_kb = msg.length.to_f / 1024.0

puts "Allocating a big array of strings of length #{msg.length}."
y = Array.new
begin
    while true do
        y << msg.dup
        est_size = y.length * max_msg_kb * 1024
        if est_size >= MAX_ALLOC then
            puts "We've done enough:"
            puts "\tArray size            = #{y.length}"
            puts "\tEstimated memory size = ruby + #{est_size / 1024 / 1024} MB"
            exit 0
        end
    end
rescue SystemExit => se
    exit 0
rescue Exception => e
    begin
        puts "Caught exception"
        puts "\tArray size            = #{y.length}"
        puts "\tEstimated memory size = ruby + #{(y.length * max_msg_kb) / 1024} MB"
        puts
        puts e.backtrace.join("\n")
        puts " 1) Caught exception #{$!}"
        puts " 2) Caught exception #{e.class}"
    rescue Exception => e2
        puts e2.backtrace.join('\n')
    end
    exit 1
end

exit 0

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