From: Eric Mahurin <eric_mahurin@...>
Date: 2005-10-16T23:05:59+09:00
Subject: Re: Help! define_method leaking procs...

--- "Ara.T.Howard" <Ara.T.Howard@noaa.gov> wrote:

> On Sun, 16 Oct 2005, Ara.T.Howard wrote:
> 
> > this is quite suspect:
> >
> > [ahoward@localhost ~]$ for i in $(seq 0 18);do
> >  printf "$i => ";
> >  ruby -e' class << self; (2**ARGV.shift.to_i).times{|n| s =
> '42' * n; 
> > define_method("f#{ n }"){ 42 }}; end; GC::start; p
> IO::read("/proc/#{ $$ 
> > }/status").grep(/VmSize/) ' $i;
> > done
> >
> > 0 => ["VmSize:\t    2840 kB\n"]
> > 1 => ["VmSize:\t    2840 kB\n"]
> > 2 => ["VmSize:\t    2840 kB\n"]
> > 3 => ["VmSize:\t    2840 kB\n"]
> > 4 => ["VmSize:\t    2844 kB\n"]
> > 5 => ["VmSize:\t    2840 kB\n"]
> > 6 => ["VmSize:\t    2840 kB\n"]
> > 7 => ["VmSize:\t    2844 kB\n"]
> > 8 => ["VmSize:\t    2976 kB\n"]
> > 9 => ["VmSize:\t    3456 kB\n"]
> > 10 => ["VmSize:\t    3720 kB\n"]
> > 11 => ["VmSize:\t    4380 kB\n"]
> > 12 => ["VmSize:\t    6072 kB\n"]
> > 13 => ["VmSize:\t    9456 kB\n"]
> > 14 => ["VmSize:\t   15996 kB\n"]
> > 15 => ["VmSize:\t   28704 kB\n"]
> > 16 => ["VmSize:\t   53352 kB\n"]
> > 17 => ["VmSize:\t  101220 kB\n"]
> > 18 => ["VmSize:\t  194404 kB\n"]
> >
> >
> > note the progression is linear until 13 (note irony) and
> then climbs
> > exponentially - doubling each time.
> 
> and even wrapping in a method doesn't seem to help
> 
>    [ahoward@localhost ~]$ ruby a.rb 15
>           1 => VmSize:         2844 kB
>           2 => VmSize:         2848 kB
>           4 => VmSize:         2848 kB
>           8 => VmSize:         2848 kB
>          16 => VmSize:         2848 kB
>          32 => VmSize:         2848 kB
>          64 => VmSize:         2976 kB
>         128 => VmSize:         3108 kB
>         256 => VmSize:         3724 kB
>         512 => VmSize:         4648 kB
>        1024 => VmSize:         5572 kB
>        2048 => VmSize:         9904 kB
>        4096 => VmSize:        13104 kB
>        8192 => VmSize:        27016 kB
>       16384 => VmSize:        46676 kB
> 
> 
>    [ahoward@localhost ~]$ cat a.rb
>    class Object
>      def gen_method
>        klass = Class === self ? self : self.class
>        class << klass
>          define_method("f#{ rand(2 ** 42) }"){ 42 }
>        end
>      end
>    end
> 
>    limit = Integer ARGV.shift
> 
>    limit.times do |l|
>      n = 2 ** l
> 
>      n.times{|i| s = '42' * i and gen_method}
> 
>      GC::start
> 
>      printf "% 8d => %s", n, IO::read("/proc/#{ $$
> }/status").grep(/VmSize/)
>    end
> 
> still exponential after a threshold...

The other leaking examples were technically quadratic (O(n**2))
were they should have been O(n).  The above one is also O(n). 
Take on the "s = '42' * i and" and you'll see the same memory
usage.  I don't see an issue in the above example.  It's just
that the memory usage was so small for anything below n=1024,
that it probably didn't have to grow much beyond what ruby had
allocated to it when it started up.



		
__________________________________ 
Yahoo! Music Unlimited 
Access over 1 million songs. Try it free.
http://music.yahoo.com/unlimited/