rabbitmq的死信队列

目录

成为死信的条件

消息TTL过期

队列达到最大长度

消息被拒

延迟队列

延迟队列使用场景

[消息设置 TTL](#消息设置 TTL)

[队列设置 TTL](#队列设置 TTL)

两者区别

---

producer 将消息投递到 broker 或者直接到 queue 里了， consumer 从 queue 取出消息
进行消费，但某些时候由于特定的 原因导致 queue 中的某些消息无法被消费 ，这样的消息如果没有后续的处理，就变成了死信，有死信自然就有了死信队列。

成为死信的条件

1. 超过消息的存活时间（TTL）：可以为消息设置一个存活时间，在该时间段之后，如果消息还未被消费或者被重新投递到其他队列，该消息将成为死信。

2. 消息被拒绝（Reject）：当消息被消费者拒绝接收时，可以选择将该消息重新投递到另一个队列或将其标记为死信。

3. 消息达到最大重试次数：可以通过在消费者端设置重试次数限制，当消息达到一定的重试次数而仍然无法被消费时，该消息将成为死信。

4. 队列满溢（Queue Overflow）：当一个队列的消息数量已经超过队列的最大容量限制时，新消息无法进入队列，而被视为死信。

消息TTL过期

生产者

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;

public class Producer {
      private static final String NORMAL_EXCHANGE = "normal_exchange";

      public static void main(String[] argv) throws Exception {
      try (Channel channel = RabbitMqUtils.getChannel()) {
      channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
        //设置消息的 TTL 时间
        AMQP.BasicProperties properties = new AMQP.BasicProperties().builder().expiration("10000").build();
        //该信息是用作演示队列个数限制
        for (int i = 1; i <11 ; i++) {
          String message="info"+i;
          channel.basicPublish(NORMAL_EXCHANGE, "zhangsan", properties,
          message.getBytes());
          System.out.println("生产者发送消息:"+message);
        }
      }
   }
}

消费者1

import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;

import java.util.HashMap;
import java.util.Map;

public class Consumer01 {
       //普通交换机名称
       private static final String NORMAL_EXCHANGE = "normal_exchange";
       //死信交换机名称
       private static final String DEAD_EXCHANGE = "dead_exchange";
       public static void main(String[] argv) throws Exception {
           Channel channel = RabbitMqUtils.getChannel();
           //声明死信和普通交换机 类型为 direct
           channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
           channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
           //声明死信队列
           String deadQueue = "dead-queue";
           channel.queueDeclare(deadQueue, false, false, false, null);
           //死信队列绑定死信交换机与 routingkey
           channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
           //正常队列绑定死信队列信息
           Map<String, Object> params = new HashMap<>();
           //正常队列设置死信交换机 参数 key 是固定值
           params.put("x-dead-letter-exchange", DEAD_EXCHANGE);
           //正常队列设置死信 routing-key 参数 key 是固定值
           params.put("x-dead-letter-routing-key", "lisi");

           String normalQueue = "normal-queue";
           channel.queueDeclare(normalQueue, false, false, false, params);
           channel.queueBind(normalQueue, NORMAL_EXCHANGE, "zhangsan");
           System.out.println("等待接收消息.....");
           DeliverCallback deliverCallback = (consumerTag, delivery) -> {
              String message = new String(delivery.getBody(), "UTF-8");
              System.out.println("Consumer01 接收到消息"+message);
           };
           channel.basicConsume(normalQueue, true, deliverCallback, consumerTag -> {
           });
       }
}

消费者2

import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;

public class Consumer02 {
      private static final String DEAD_EXCHANGE = "dead_exchange";
      public static void main(String[] argv) throws Exception {
      Channel channel = RabbitMqUtils.getChannel();
      channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
      String deadQueue = "dead-queue";
      channel.queueDeclare(deadQueue, false, false, false, null);
      channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
      System.out.println("等待接收死信队列消息.....");
      DeliverCallback deliverCallback = (consumerTag, delivery) -> {
         String message = new String(delivery.getBody(), "UTF-8");
         System.out.println("Consumer02 接收死信队列的消息" + message);
      };
      channel.basicConsume(deadQueue, true, deliverCallback, consumerTag -> {
      });
      }
}

关闭消费者1，模拟出故障

正常队列

消息超时进入死信队列

死信队列接收信息

队列达到最大长度

生产者

import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;

public class Producer {
     private static final String NORMAL_EXCHANGE = "normal_exchange";
     public static void main(String[] argv) throws Exception {
         try (Channel channel = RabbitMqUtils.getChannel()) {
         channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
         //该信息是用作演示队列个数限制
         for (int i = 1; i <11 ; i++) {
         String message="info"+i;
         channel.basicPublish(NORMAL_EXCHANGE,"zhangsan",null, message.getBytes());
         System.out.println("生产者发送消息:"+message);
         }
         }
     }
}

消费者1

import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;

import java.util.HashMap;
import java.util.Map;

public class Consumer01 {
       //普通交换机名称
       private static final String NORMAL_EXCHANGE = "normal_exchange";
       //死信交换机名称
       private static final String DEAD_EXCHANGE = "dead_exchange";

       public static void main(String[] argv) throws Exception {
           Channel channel = RabbitMqUtils.getChannel();
           //声明死信和普通交换机 类型为 direct
           channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
           channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
           //声明死信队列
           String deadQueue = "dead-queue";
           channel.queueDeclare(deadQueue, false, false, false, null);
           //死信队列绑定死信交换机与 routingkey
           channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
           //正常队列绑定死信队列信息
           Map<String, Object> params = new HashMap<>();
           //正常队列设置死信交换机 参数 key 是固定值
           params.put("x-dead-letter-exchange", DEAD_EXCHANGE);
           //正常队列设置死信 routing-key 参数 key 是固定值
           params.put("x-dead-letter-routing-key", "lisi");
           // 设置正常队列长度的限制
           params.put("x-max-length",6);

           String normalQueue = "normal-queue";
           channel.queueDeclare(normalQueue, false, false, false, params);
           channel.queueBind(normalQueue, NORMAL_EXCHANGE, "zhangsan");
           System.out.println("等待接收消息.....");
           DeliverCallback deliverCallback = (consumerTag, delivery) -> {
              String message = new String(delivery.getBody(), "UTF-8");
              System.out.println("Consumer01 接收到消息"+message);
           };
           channel.basicConsume(normalQueue, true, deliverCallback, consumerTag -> {
           });
       }
}

消费者2

import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;

public class Consumer02 {
      private static final String DEAD_EXCHANGE = "dead_exchange";
      public static void main(String[] argv) throws Exception {
            Channel channel = RabbitMqUtils.getChannel();
            channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
            String deadQueue = "dead-queue";
            channel.queueDeclare(deadQueue, false, false, false, null);
            channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
            System.out.println("等待接收死信队列消息.....");
            DeliverCallback deliverCallback = (consumerTag, delivery) -> {
               String message = new String(delivery.getBody(), "UTF-8");
               System.out.println("Consumer02 接收死信队列的消息" + message);
            };
            channel.basicConsume(deadQueue, true, deliverCallback, consumerTag -> {
            });
      }
}

关闭消费者1，模拟接收不到信息

死信队列消费了四个消息

分析：生产者产生10个消息，正常队列只能接受6个消息，多的消息便被转移到死信队列去了

消息被拒

生产者

import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;

public class Producer {
     private static final String NORMAL_EXCHANGE = "normal_exchange";
     public static void main(String[] argv) throws Exception {
         try (Channel channel = RabbitMqUtils.getChannel()) {
         channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
         //该信息是用作演示队列个数限制
         for (int i = 1; i <11 ; i++) {
         String message="info"+i;
         channel.basicPublish(NORMAL_EXCHANGE,"zhangsan",null, message.getBytes());
         System.out.println("生产者发送消息:"+message);
         }
         }
     }
}

消费者1

import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;

import java.util.HashMap;
import java.util.Map;

public class Consumer01 {
     //普通交换机名称
     private static final String NORMAL_EXCHANGE = "normal_exchange";
     //死信交换机名称
     private static final String DEAD_EXCHANGE = "dead_exchange";
     public static void main(String[] argv) throws Exception {
         Channel channel = RabbitMqUtils.getChannel();
         //声明死信和普通交换机 类型为 direct
         channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
         channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
         //声明死信队列
         String deadQueue = "dead-queue";
         channel.queueDeclare(deadQueue, false, false, false, null);
         //死信队列绑定死信交换机与 routingkey
         channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
         //正常队列绑定死信队列信息
         Map<String, Object> params = new HashMap<>();
         //正常队列设置死信交换机 参数 key 是固定值
         params.put("x-dead-letter-exchange", DEAD_EXCHANGE);
         //正常队列设置死信 routing-key 参数 key 是固定值
         params.put("x-dead-letter-routing-key", "lisi");
         String normalQueue = "normal-queue";
         channel.queueDeclare(normalQueue, false, false, false, params);
         channel.queueBind(normalQueue, NORMAL_EXCHANGE, "zhangsan");
         System.out.println("等待接收消息.....");
         DeliverCallback deliverCallback = (consumerTag, delivery) -> {
             String message = new String(delivery.getBody(), "UTF-8");
             if(message.equals("info5")){
                 System.out.println("Consumer01 接收到消息" + message + "并拒绝签收该消息");
                 //requeue 设置为 false 代表拒绝重新入队 该队列如果配置了死信交换机将发送到死信队列中
                 channel.basicReject(delivery.getEnvelope().getDeliveryTag(), false);
             }else {
                 System.out.println("Consumer01 接收到消息"+message);
                 channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);
             }
         };
         boolean autoAck = false;
         channel.basicConsume(normalQueue, autoAck, deliverCallback, consumerTag -> {
         });
     }
}

消费者2

import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;

public class Consumer02 {
      private static final String DEAD_EXCHANGE = "dead_exchange";
      public static void main(String[] argv) throws Exception {
            Channel channel = RabbitMqUtils.getChannel();
            channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
            String deadQueue = "dead-queue";
            channel.queueDeclare(deadQueue, false, false, false, null);
            channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
            System.out.println("等待接收死信队列消息.....");
            DeliverCallback deliverCallback = (consumerTag, delivery) -> {
               String message = new String(delivery.getBody(), "UTF-8");
               System.out.println("Consumer02 接收死信队列的消息" + message);
            };
            channel.basicConsume(deadQueue, true, deliverCallback, consumerTag -> {
            });
      }
}

结果

消费者1，拒绝接受消息info5，info5进入死信队列

消费者2，死信队列接受到info5

延迟队列

延时队列 , 队列内部是有序的，最重要的特性就体现在它的延时属性上，延时队列中的元素是希望
在指定时间到了以后或之前取出和处理，简单来说，延时队列就是用来存放需要在指定时间被处理的 元素的队列。

延迟队列使用场景

1. 订单在十分钟之内未支付则自动取消
2. 新创建的店铺，如果在十天内都没有上传过商品，则自动发送消息提醒。
3. 用户注册成功后，如果三天内没有登陆则进行短信提醒。
4. 用户发起退款，如果三天内没有得到处理则通知相关运营人员。
5. 预定会议后，需要在预定的时间点前十分钟通知各个与会人员参加会议

消息设置 TTL

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;

public class Producer {
      private static final String NORMAL_EXCHANGE = "normal_exchange";

      public static void main(String[] argv) throws Exception {
      try (Channel channel = RabbitMqUtils.getChannel()) {
      channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
        //设置消息的 TTL 时间
        AMQP.BasicProperties properties = new AMQP.BasicProperties().builder().expiration("10000").build();
        //该信息是用作演示队列个数限制
        for (int i = 1; i <11 ; i++) {
          String message="info"+i;
          channel.basicPublish(NORMAL_EXCHANGE, "zhangsan", properties,
          message.getBytes());
          System.out.println("生产者发送消息:"+message);
        }
      }
   }
}

队列设置 TTL

import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;

import java.util.HashMap;
import java.util.Map;

public class Consumer01 {
     //普通交换机名称
     private static final String NORMAL_EXCHANGE = "normal_exchange";
     //死信交换机名称
     private static final String DEAD_EXCHANGE = "dead_exchange";
     public static void main(String[] argv) throws Exception {
         Channel channel = RabbitMqUtils.getChannel();
         //声明死信和普通交换机 类型为 direct
         channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
         channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
         //声明死信队列
         String deadQueue = "dead-queue";
         channel.queueDeclare(deadQueue, false, false, false, null);
         //死信队列绑定死信交换机与 routingkey
         channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
         //正常队列绑定死信队列信息
         Map<String, Object> params = new HashMap<>();
         //正常队列设置死信交换机 参数 key 是固定值
         params.put("x-dead-letter-exchange", DEAD_EXCHANGE);
         //正常队列设置死信 routing-key 参数 key 是固定值
         params.put("x-dead-letter-routing-key", "lisi");
         // 设置 TTL 值为 5000 毫秒（5 秒）
         params.put("x-message-ttl", 5000);
         String normalQueue = "normal-queue";
         channel.queueDeclare(normalQueue, false, false, false, params);
         channel.queueBind(normalQueue, NORMAL_EXCHANGE, "zhangsan");
         System.out.println("等待接收消息.....");
         DeliverCallback deliverCallback = (consumerTag, delivery) -> {
             String message = new String(delivery.getBody(), "UTF-8");
             if(message.equals("info5")){
                 System.out.println("Consumer01 接收到消息" + message + "并拒绝签收该消息");
                 //requeue 设置为 false 代表拒绝重新入队 该队列如果配置了死信交换机将发送到死信队列中
                 channel.basicReject(delivery.getEnvelope().getDeliveryTag(), false);
             }else {
                 System.out.println("Consumer01 接收到消息"+message);
                 channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);
             }
         };
         boolean autoAck = false;
         channel.basicConsume(normalQueue, autoAck, deliverCallback, consumerTag -> {
         });
     }
}

两者区别

如果设置了队列的 TTL 属性，那么一旦消息过期，就会被队列丢弃 ( 如果配置了死信队列被丢到死信队列中) ，而第二种方式，消息即使过期，也不一定会被马上丢弃，因为 消息是否过期是在即将投递到消费者 之前判定的 ，如果当前队列有严重的消息积压情况，则已过期的消息也许还能存活较长时间；另外，还需 要注意的一点是，如果不设置 TTL ，表示消息永远不会过期，如果将 TTL 设置为 0 ，则表示除非此时可以 直接投递该消息到消费者，否则该消息将会被丢弃。