ActiveMQ_007：Network Connector 配置参数decreaseNetworkConsumerPriority的含义（摘录+整理）

1. 默认情况下，ActiveMQ会平均分配消息到多个Consumers。

可以看到，3个Consumer，每个Consumer都消费了20条消息。

2. 现在来看一个复杂一些的情况，部署拓扑图如下：
Broker-1 单向转发消息到 Broker-2
Producer 发送消息到Broker-1
Consumer-1监听Broker-1，距离消息比较“近”。
Consumer-2监听Broker-2，距离消息比较“远”。

 

  Broker-1上的activemq.xml的networkConnectors配置片段如下：

   <networkConnectors>
                <networkConnector
                        name="T:broker1->broker2"
                        uri="static:(tcp://localhost:61626)"
                        duplex="false"
                        decreaseNetworkConsumerPriority="false"
                        networkTTL="2"
                        dynamicOnly="true">
                        <excludedDestinations>
                                <queue physicalName=">" />
                        </excludedDestinations>
                </networkConnector>
                <networkConnector
                        name="Q:broker1->broker2"
                        uri="static:(tcp://localhost:61626)"
                        duplex="false"
                        decreaseNetworkConsumerPriority="false"
                        networkTTL="2"
                        dynamicOnly="true">
                        <excludedDestinations>
                                <topic physicalName=">" />
                        </excludedDestinations>
                </networkConnector>
        </networkConnectors>

networkTTL="2"，表示最多允许经过几个Broker，这里只经过了一个Broker，小于2。

在Broker-1的Console上，查看Queue的详细信息：

发现100条消息依然平均分配到了两个Consumer上，各自消费了50条。

  

修改Broker-1上的activemq.xml的networkConnectors配置片段如下：

   <networkConnectors>
                <networkConnector
                        name="T:broker1->broker2"
                        uri="static:(tcp://localhost:61626)"
                        duplex="false"
                        decreaseNetworkConsumerPriority="true"
                        networkTTL="2"
                        dynamicOnly="true">
                        <excludedDestinations>
                                <queue physicalName=">" />
                        </excludedDestinations>
                </networkConnector>
                <networkConnector
                        name="Q:broker1->broker2"
                        uri="static:(tcp://localhost:61626)"
                        duplex="false"
                        decreaseNetworkConsumerPriority="true"
                        networkTTL="2"
                        dynamicOnly="true">
                        <excludedDestinations>
                                <topic physicalName=">" />
                        </excludedDestinations>
                </networkConnector>
        </networkConnectors>

在Broker-1的Console上，查看Queue的详细信息：

发现这次100条消息全被分配给了Consumer-1，因为它距离消息最“近”。

参考文献：
1. http://akuntamukkala.blogspot.com/2014/02/activemq-network-of-brokers-explained.html
2. http://akuntamukkala.blogspot.com/2014/02/activemq-network-of-brokers-explained_28.html
3. http://akuntamukkala.blogspot.com/2014/03/activemq-network-of-brokers-explained.html
4. http://akuntamukkala.blogspot.com/2014/03/activemq-network-of-brokers-explained_26.html
5. http://akuntamukkala.blogspot.com/2014/05/activemq-network-of-brokers-explained.html