get memory size of a data structure

memtest.pl

#!/usr/bin/perl
# $Id$
# created by Dave Messina on 2010-04-28

use Modern::Perl;
use Devel::Size qw(total_size);

my %hash;

say "Empty: ", total_size (\%hash), ' bytes';

foreach my $number (1..100000) {
    my $key = 1 . $number;
    $hash{$key} = 1;
}

say "Full: ", total_size (\%hash), ' bytes';