$manager->run_on_finish( 
      sub {
         my ( $pid, $exit_code, $ident, $signal, $core ) = @_;
         if ( $core ) {
            print "Process $ident (pid: $pid) core dumped.\n";
         } else {
            print "Process $ident (pid: $pid) exited 
            print "with code $exit_code and signal $signal.\n";
         }
      }
   );