[GitHub] [rocketmq] tianliuliu commented on a change in pull request #3694: [RIP-28] light message queue(LMQ)

[GitBox <gi...@apache.org>]

tianliuliu commented on a change in pull request #3694:
URL: https://github.com/apache/rocketmq/pull/3694#discussion_r782689625



##########
File path: docs/cn/Example_LMQ.md
##########
@@ -0,0 +1,75 @@
+# Light message queue (LMQ)
+
+
+## 一、broker启动配置
+
+
+broker.conf文件需要增加以下的配置项，开启LMQ开关，这样就可以识别LMQ相关属性的消息，进行原子分发消息到LMQ队列
+```properties
+enableLmq = true
+enableMultiDispatch = true
+```
+## 二、发送消息
+发送消息的时候通过设置 INNER_MULTI_DISPATCH 属性，LMQ queue使用逗号分割，queue前缀必须是 %LMQ%，这样broker就可以识别LMQ queue.
+```java
+DefaultMQProducer producer = new DefaultMQProducer("please_rename_unique_group_name");
+producer.setNamesrvAddr("name-server1-ip:9876;name-server2-ip:9876");
+producer.start();
+
+
+/*
+* Create a message instance, specifying topic, tag and message body.
+*/
+Message msg = new Message("TopicTest" /* Topic */,
+                          "TagA" /* Tag */,
+                          ("Hello RocketMQ " + i).getBytes(RemotingHelper.DEFAULT_CHARSET) /* Message body */
+                         );
+/*
+* INNER_MULTI_DISPATCH property and PREFIX must start as "%LMQ%",
+* If it is multiple LMQ, need to use “,” split
+*/
+message.putUserProperty("INNER_MULTI_DISPATCH", "%LMQ%123,%LMQ%456");
+/*
+* Call send message to deliver message to one of brokers.
+*/
+SendResult sendResult = producer.send(msg);
+```
+## 三、拉取消息
+LMQ queue在每个broker上只有一个queue，也即queueId为0， 指明轻量级的MessageQueue，就可以拉取消息进行消费。
+```java
+DefaultMQPullConsumer defaultMQPullConsumer = new DefaultMQPullConsumer();
+defaultMQPullConsumer.setNamesrvAddr("name-server1-ip:9876;name-server2-ip:9876");
+defaultMQPullConsumer.setVipChannelEnabled(false);
+defaultMQPullConsumer.setConsumerGroup("CID_RMQ_SYS_LMQ_TEST");
+defaultMQPullConsumer.setInstanceName("CID_RMQ_SYS_LMQ_TEST");
+defaultMQPullConsumer.setRegisterTopics(new HashSet<>(Arrays.asList("TopicTest")));
+defaultMQPullConsumer.setBrokerSuspendMaxTimeMillis(2000);
+defaultMQPullConsumer.setConsumerTimeoutMillisWhenSuspend(3000);
+defaultMQPullConsumer.start();
+
+String brokerName = "set broker Name";
+MessageQueue mq = new MessageQueue("%LMQ%123", brokerName, 0);
+
+Long offset = defaultMQPullConsumer.maxOffset(mq);
+
+defaultMQPullConsumer.pullBlockIfNotFound(

Review comment:
       1. request queueId[3] is illegal, TopicConfig [topicName=TopicTest, readQueueNums=1, writeQueueNums=1, perm=RW-, topicFilterType=SINGLE_TAG, topicSysFlag=0, order=false] Producer: 172.18.40.26:50188 BROKER: 172.18.40.26:10911
   For more information, please visit the url, http://rocketmq.apache.org/docs/faq/
   
   TopicTest 多创建几个队列就可以了 这个只有一个队列 所以队列queueId 3拿不到
   2. broker-a 不存在问题 就是你部署的mq集群中，没有这个broke




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