Someone

use Thread;

sub a{ print "MAIN\n"; 1 };

$global::var = \&a;

my $t1 = Thread->new(\&run, NULL);
my $t2 = Thread->new(\&run, NULL);


$t1->join;
$t2->join;

sub run
{
	print "Thread\n";
	&{$global::var}; 
}