MCE has been released for Perl. This is how one could do this with MCE. Not knowing what you're wanting to do in the main caller, the example has 2 callback functions.

Both workers run in parallel below. Workers never exit due to running inside a never ending loop. The do method passes data back to the main process or thread.

http://code.google.com/p/many-core-engine-perl/

https://metacpan.org/module/MCE

use MCE;

sub proc1 {
   my $hash_ref = shift;
   for (keys %{ $hash_ref }) {
      print $_, ': ', $hash_ref->{$_}, "\n";
   }
}

sub proc2 {
   my $hash_ref = shift;
   for (keys %{ $hash_ref }) {
      print $_, ': ', $hash_ref->{$_}, "\n";
   }
}

my $mce = MCE->new(
   max_workers => 2,

   user_func => sub {
      my ($self) = @_;

      while (1) {
         if ($self->wid == 1) {
            my %hash1 = ( 'key1' => 'value1' );
            $self->do('proc1', \%hash1);
         }
         else {
            my %hash2 = ( 'key2' => 'value2' );
            $self->do('proc2', \%hash2);
         }
         sleep(600);
      }
   }
);

$mce->run;
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