public function executeAll($max = 50)
    {
        $sth = $this->getDb()->prepare('SELECT * FROM ' . $this->queueTable . ' WHERE 1');
        $sth->execute();
        foreach($sth->fetchAll() as $queue) {
            $q = new Queue($queue['queue_name'], $queue['timeout']);
            $q->setManager($this);
            $q->execute($max);
        }
    }