public function newQueue(callable $onEnd = null)
{
Verify::isTrue(!isset($this->queues[$this->start_queue_id]));
$this->action_queues[$this->start_queue_id] = array();
$this->idle_queues[$this->start_queue_id] = array();
$this->end_handles[$this->start_queue_id] = $onEnd;
Logger::debug("[MQ {$this->start_queue_id}] created");
return $this->start_queue_id++;
}