i finished my solution to the problem...

sub main_loop {
  my $parser_thread;
  while(
    still_running()
    #and $hit_count < $hit_limit       #could be commented out
    and time() < $expiration
    and ! $QUIT_NOW
  ) {
    #if we have less than 23 (including mysql) then make a new one
    if (scalar threads->list(threads::running) < 23 and schedule_count
+()){
      $parser_thread = async {process_url( next_scheduled_url() );};
      }
    #cleanup dead threads
    if (threads->list(threads::joinable)){
      foreach $parser_thread (threads->list(threads::joinable)){
        $parser_thread->join;
        undef $parser_thread;
        }
      }
  }
  return;
}

sub still_running{
  if (schedule_count()){return 1;}
  else {
    if (scalar threads->list(threads::running)){return 1;}
    else {return 0;}
    }
  }
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The leak is either non-existent or drastically reduced. Thanks for the help everyone