RocketMq如何保证消费顺序

Posted 2023-04-27

参考技术A 集群模式下锁队列保证消息被同一个consumer消费，往broker定时发送锁命令
本地消费时不论集群模式和广播模式都会有本地队列锁进行锁定
保证同一个队列只会同时被一个消费者线程锁定

本地消费时也按队列进行锁定操作

MQConsumerInner获取到消息就把消息放到ProcessQueue，并且会启动一个消费者任务
ProcessQueue底层用treeMap存储消息保证消息获取时按消息偏移量大小顺序获取，并在进行读写操作时用读写锁保证其线程安全性。

本地消费失败就会将消息重新放入processQueue里，达到最大次数的消费就会把消息发送回broker

rocketMQ之顺序消费

消息有序指的是可以按照消息的发送顺序来消费(FIFO)。RocketMQ可以严格的保证消息有序，可以分为分区有序或者全局有序。

顺序消费的原理解析，在默认的情况下消息发送会采取Round Robin轮询方式把消息发送到不同的queue(分区队列)；而消费消息的时候从多个queue上拉取消息，这种情况发送和消费是不能保证顺序。但是如果控制发送的顺序消息只依次发送到同一个queue中，消费的时候只从这个queue上依次拉取，则就保证了顺序。当发送和消费参与的queue只有一个，则是全局有序；如果多个queue参与，则为分区有序，即相对每个queue，消息都是有序的。

下面用订单进行分区有序的示例。一个订单的顺序流程是：创建、付款、推送、完成。订单号相同的消息会被先后发送到同一个队列中，消费时，同一个OrderId获取到的肯定是同一个队列。

1 顺序消息生产

package org.apache.rocketmq.example.order2;

import org.apache.rocketmq.client.producer.DefaultMQProducer;
import org.apache.rocketmq.client.producer.MessageQueueSelector;
import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.common.message.MessageQueue;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
* Producer，发送顺序消息
*/
public class Producer 

   public static void main(String[] args) throws Exception 
       DefaultMQProducer producer = new DefaultMQProducer("please_rename_unique_group_name");

       producer.setNamesrvAddr("127.0.0.1:9876");

       producer.start();

       String[] tags = new String[]"TagA", "TagC", "TagD";

       // 订单列表
       List<OrderStep> orderList = new Producer().buildOrders();

       Date date = new Date();
       SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
       String dateStr = sdf.format(date);
       for (int i = 0; i < 10; i++) 
           // 加个时间前缀
           String body = dateStr + " Hello RocketMQ " + orderList.get(i);
           Message msg = new Message("TopicTest", tags[i % tags.length], "KEY" + i, body.getBytes());

           SendResult sendResult = producer.send(msg, new MessageQueueSelector() 
               @Override
               public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) 
                   Long id = (Long) arg;  //根据订单id选择发送queue
                   long index = id % mqs.size();
                   return mqs.get((int) index);
               
           , orderList.get(i).getOrderId());//订单id

           System.out.println(String.format("SendResult status:%s, queueId:%d, body:%s",
               sendResult.getSendStatus(),
               sendResult.getMessageQueue().getQueueId(),
               body));
       

       producer.shutdown();
   

   /**
    * 订单的步骤
    */
   private static class OrderStep 
       private long orderId;
       private String desc;

       public long getOrderId() 
           return orderId;
       

       public void setOrderId(long orderId) 
           this.orderId = orderId;
       

       public String getDesc() 
           return desc;
       

       public void setDesc(String desc) 
           this.desc = desc;
       

       @Override
       public String toString() 
           return "OrderStep" +
               "orderId=" + orderId +
               ", desc='" + desc + '\\'' +
               '';
       
   

   /**
    * 生成模拟订单数据
    */
   private List<OrderStep> buildOrders() 
       List<OrderStep> orderList = new ArrayList<OrderStep>();

       OrderStep orderDemo = new OrderStep();
       orderDemo.setOrderId(15103111039L);
       orderDemo.setDesc("创建");
       orderList.add(orderDemo);

       orderDemo = new OrderStep();
       orderDemo.setOrderId(15103111065L);
       orderDemo.setDesc("创建");
       orderList.add(orderDemo);

       orderDemo = new OrderStep();
       orderDemo.setOrderId(15103111039L);
       orderDemo.setDesc("付款");
       orderList.add(orderDemo);

       orderDemo = new OrderStep();
       orderDemo.setOrderId(15103117235L);
       orderDemo.setDesc("创建");
       orderList.add(orderDemo);

       orderDemo = new OrderStep();
       orderDemo.setOrderId(15103111065L);
       orderDemo.setDesc("付款");
       orderList.add(orderDemo);

       orderDemo = new OrderStep();
       orderDemo.setOrderId(15103117235L);
       orderDemo.setDesc("付款");
       orderList.add(orderDemo);

       orderDemo = new OrderStep();
       orderDemo.setOrderId(15103111065L);
       orderDemo.setDesc("完成");
       orderList.add(orderDemo);

       orderDemo = new OrderStep();
       orderDemo.setOrderId(15103111039L);
       orderDemo.setDesc("推送");
       orderList.add(orderDemo);

       orderDemo = new OrderStep();
       orderDemo.setOrderId(15103117235L);
       orderDemo.setDesc("完成");
       orderList.add(orderDemo);

       orderDemo = new OrderStep();
       orderDemo.setOrderId(15103111039L);
       orderDemo.setDesc("完成");
       orderList.add(orderDemo);

       return orderList;
   

2 顺序消费消息

package org.apache.rocketmq.example.order2;

import org.apache.rocketmq.client.consumer.DefaultMQPushConsumer;
import org.apache.rocketmq.client.consumer.listener.ConsumeOrderlyContext;
import org.apache.rocketmq.client.consumer.listener.ConsumeOrderlyStatus;
import org.apache.rocketmq.client.consumer.listener.MessageListenerOrderly;
import org.apache.rocketmq.common.consumer.ConsumeFromWhere;
import org.apache.rocketmq.common.message.MessageExt;

import java.util.List;
import java.util.Random;
import java.util.concurrent.TimeUnit;

/**
* 顺序消息消费，带事务方式（应用可控制Offset什么时候提交）
*/
public class ConsumerInOrder 

   public static void main(String[] args) throws Exception 
       DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("please_rename_unique_group_name_3");
       consumer.setNamesrvAddr("127.0.0.1:9876");
       /**
        * 设置Consumer第一次启动是从队列头部开始消费还是队列尾部开始消费<br>
        * 如果非第一次启动，那么按照上次消费的位置继续消费
        */
       consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);

       consumer.subscribe("TopicTest", "TagA || TagC || TagD");

       consumer.registerMessageListener(new MessageListenerOrderly() 

           Random random = new Random();

           @Override
           public ConsumeOrderlyStatus consumeMessage(List<MessageExt> msgs, ConsumeOrderlyContext context) 
               context.setAutoCommit(true);
               for (MessageExt msg : msgs) 
                   // 可以看到每个queue有唯一的consume线程来消费, 订单对每个queue(分区)有序
                   System.out.println("consumeThread=" + Thread.currentThread().getName() + "queueId=" + msg.getQueueId() + ", content:" + new String(msg.getBody()));
               

               try 
                   //模拟业务逻辑处理中...
                   TimeUnit.SECONDS.sleep(random.nextInt(10));
                catch (Exception e) 
                   e.printStackTrace();
               
               return ConsumeOrderlyStatus.SUCCESS;
           
       );

       consumer.start();

       System.out.println("Consumer Started.");
   

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