_houseKeepingTasks = new ScheduledThreadPoolExecutor(_vhostConfig.getHouseKeepingThreadCount());
_queueRegistry = new DefaultQueueRegistry(this);
_queueFactory = new AMQQueueFactory(this, _queueRegistry);
_exchangeFactory = new DefaultExchangeFactory(this);
_exchangeRegistry = new DefaultExchangeRegistry(this, _queueRegistry);