Creating a thread pool within a callback cause segfault

Hi,

I am having problems mixing the Thread::Pool and Event modules. I can 
access the a pool created outside of a callback, but can't create a pool 
within the callback. You can see it by running the program below with 
and without the argument 'out'.

Please help,
-gr

#!perl
use Thread::Pool;
use Event;
$Event::DebugLevel = 5;

my $var;
my $pool;

pool() if $ARGV[0] eq 'out';

my $timer = Event->timer(
    desc => 'pool_test',
    at => time + 3,
    cb       => \&callback
);

Event::loop;

sub pool {
    $pool = Thread::Pool->new(
        {
            do => sub {$var++}
        }
    ) unless defined $pool;
    return $pool;
}

sub callback {
    my $pool = pool();
    my $id     = $pool->job();
    my $result = $pool->result($id);
    print "var is: ", $result, "\n";
}