Mojo::IOLoop->recurring(
    0 => sub {
            for ($active + 1 .. $max_conn) {

            # Dequeue or halt if there are no active crawlers anymore
            return ($active or Mojo::IOLoop->stop or $totalPagesVisited > $maxPages)
            unless my $url = shift @urls;

            # Fetch non-blocking just by adding
            # a callback and marking as active
            ++$active;
            say "getting link: $url";
            ($depth, $myLink) = split ('\|', $url);
            $ua->get($myLink => \&get_callback);
            }
        }
    );
sub get_callback {
    my (undef, $tx) = @_;
......
    push(@urls, "$depth+1|$newLink");
......
}