限流及重回隊列及TTL消息及死信隊列

文章目錄

消費端限流

什麼是消費端的限流？
假設一個場景，首先，我們RabbitMQ服務器有上萬條未處理的消息，我們隨便打開一個消費者客戶端，會出現下面情況：
巨量的消息瞬間全部推送過來，但是我們單個客戶端無法同時處理這麼多數據

消費端限流RabbitMQ提供的解決方案
RabbitMQ提供了一種qos（服務質量保證）功能，即在非自動確認消息的前提下，如果一定數目的消息（通過基於Consumer或者Channel設置Qos的值）未被確認前，不進行消費新的消息

Void BasicQos(uint prefetchSize, ushort prefetchCount, bool global);
prefetchSize：0 不限制消息大小
prefetchSize：會告訴RabbitMQ不要同時給一個消費者推送多於N個消息，即一旦有N個消息還沒有ack，則該Consumer將block（阻塞）掉，直到有消息ack
Global：true\false是否將上面設置應用於Channel；簡單來說，就是上面限制是Channel級別的還是Consumer級別

注意：
prefetchSize和global這兩項，RabbitMQ沒有實現，暫且不研究；
prefetch_count在no_ask=false的情況下生效，即在自動應答的情況下，這兩個值是不生效的；

自定義消費端代碼

package com.tang.rabbitmqapi.limit;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;

import java.io.IOException;

public class MyConsumer extends DefaultConsumer {
    private Channel channel ;

    public MyConsumer(Channel channel) {
        super(channel);
        this.channel = channel;
    }

    @Override
    public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
        System.err.println("-----------consume message----------");
        System.err.println("consumerTag: " + consumerTag);
        System.err.println("envelope: " + envelope);
        System.err.println("properties: " + properties);
        System.err.println("body: " + new String(body));

        channel.basicAck(envelope.getDeliveryTag(), false);
    }

}

消費端代碼

package com.tang.rabbitmqapi.limit;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

public class Consumer {
    public static void main(String[] args) throws Exception {
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.159.131");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();


        String exchangeName = "test_qos_exchange";
        String queueName = "test_qos_queue";
        String routingKey = "qos.#";

        channel.exchangeDeclare(exchangeName, "topic", true, false, null);
        channel.queueDeclare(queueName, true, false, false, null);
        channel.queueBind(queueName, exchangeName, routingKey);

        //1 限流方式  第一件事就是 autoAck設置爲 false
        channel.basicQos(0, 1, false);

        channel.basicConsume(queueName, false, new MyConsumer(channel));
    }
}

提供方代碼

package com.tang.rabbitmqapi.limit;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

public class Producer {
    public static void main(String[] args) throws Exception {
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.159.131");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();

        String exchange = "test_qos_exchange";
        String routingKey = "qos.save";

        String msg = "Hello RabbitMQ QOS Message";

        for(int i =0; i<5; i ++){
            channel.basicPublish(exchange, routingKey, true, null, msg.getBytes());
        }

    }
}

測試

消息的ACK與重回隊列

消費端手工ACK與NACK
消費端進行消費的時候，如果由於業務異常我們可以進行日誌的記錄，然後進行補償
如果由於服務器宕機等嚴重問題，那麼我們就需要手工進行ACK，保障消費端消費成功！

消費端的重回隊列
消費端重回隊列是爲了對沒有處理成功的消息，把消息重新回遞給Broker！
一般我們在實際應用中，都會關閉重回隊列，也就是設置爲False；因爲重回隊列消息有很大概率依然會處理失敗！

自定義消費者代碼

package com.tang.rabbitmqapi.ack;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;

import java.io.IOException;

public class MyConsumer extends DefaultConsumer {


    private Channel channel ;

    public MyConsumer(Channel channel) {
        super(channel);
        this.channel = channel;
    }

    @Override
    public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
        System.err.println("-----------consume message----------");
        System.err.println("body: " + new String(body));
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        if((Integer)properties.getHeaders().get("num") == 0) {
//            手動簽收，重回隊列
            channel.basicNack(envelope.getDeliveryTag(), false, true);
        } else {
            channel.basicAck(envelope.getDeliveryTag(), false);
        }

    }
}

消費者代碼

package com.tang.rabbitmqapi.ack;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

public class Consumer {
    public static void main(String[] args) throws Exception {
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.159.131");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();


        String exchangeName = "test_ack_exchange";
        String queueName = "test_ack_queue";
        String routingKey = "ack.#";

        channel.exchangeDeclare(exchangeName, "topic", true, false, null);
        channel.queueDeclare(queueName, true, false, false, null);
        channel.queueBind(queueName, exchangeName, routingKey);

        // 手工簽收 必須要關閉 autoAck = false
        channel.basicConsume(queueName, false, new MyConsumer(channel));
    }
}

生產者代碼

package com.tang.rabbitmqapi.ack;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

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

public class Producer {
    public static void main(String[] args) throws Exception {
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.159.131");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();

        String exchange = "test_ack_exchange";
        String routingKey = "ack.save";

        for(int i =0; i<5; i ++){
            Map<String, Object> headers = new HashMap<String, Object>();
            headers.put("num", i);
            AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder()
                    .deliveryMode(2)
                    .contentEncoding("UTF-8")
                    .headers(headers)
                    .build();
            String msg = "Hello RabbitMQ ACK Message " + i;
            channel.basicPublish(exchange, routingKey, true, properties, msg.getBytes());
        }
    }
}

測試

沒有被消費掉的將會一直循環下去

TTL消息

TTL
TTL是Time To Live的縮寫，也就是生存時間
RabbitMQ支持消息的過期時間，在消息發送時可以進行指定
RabbitMQ支持隊列的過期時間，從消息入隊列開始計算，只要超過了隊列的超時時間配置，那麼消息自動的清除

純控制檯操作（演示TTL隊列消息特點）
針對隊列，只要是這個隊列的消息，就只有這麼長的存活時間

注意：主要針對消息設置，跟交換機、隊列、消費者設置毫無關係

消費端代碼

package com.tang.rabbitmqapi.ttl;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.QueueingConsumer;

import java.util.Map;


public class Consumer {
    public static void main(String[] args) throws Exception {

        //1 創建一個ConnectionFactory, 並進行配置
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.159.131");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        //2 通過連接工廠創建連接
        Connection connection = connectionFactory.newConnection();

        //3 通過connection創建一個Channel
        Channel channel = connection.createChannel();

        //4 聲明（創建）一個隊列
        String queueName = "test001";
        channel.queueDeclare(queueName, true, false, false, null);

        //5 創建消費者
        QueueingConsumer queueingConsumer = new QueueingConsumer(channel);

        //6 設置Channel
        channel.basicConsume(queueName, true, queueingConsumer);

        while(true){
            //7 獲取消息
            QueueingConsumer.Delivery delivery = queueingConsumer.nextDelivery();
            String msg = new String(delivery.getBody());
            System.err.println("消費端: " + msg);
            Map<String, Object> headers = delivery.getProperties().getHeaders();
            System.err.println("headers get my1 value: " + headers.get("my1"));

            //Envelope envelope = delivery.getEnvelope();
        }

    }
}

生產端代碼

package com.tang.rabbitmqapi.ttl;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

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


public class Procuder {
    public static void main(String[] args) throws Exception {
        //1 創建一個ConnectionFactory, 並進行配置
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.159.131");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        //2 通過連接工廠創建連接
        Connection connection = connectionFactory.newConnection();

        //3 通過connection創建一個Channel
        Channel channel = connection.createChannel();

        Map<String, Object> headers = new HashMap<>();
        headers.put("my1", "111");
        headers.put("my2", "222");


        AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder()
                .deliveryMode(2)
                .contentEncoding("UTF-8")
                .expiration("10000")
                .headers(headers)
                .build();

        //4 通過Channel發送數據
        for(int i=0; i < 5; i++){
            String msg = "Hello RabbitMQ!";
            //1 exchange   2 routingKey
            channel.basicPublish("", "test001", properties, msg.getBytes());
        }

        //5 記得要關閉相關的連接
        channel.close();
        connection.close();
    }
}

測試

十秒後

死信隊列

死信隊列：DLX，Dead-Letter-Exchange
利用DLX，當消息在一個隊列中變成死信（dead message）之後，它能被重新publish到另一個Exchange，這個Exchange就是DLX

消息變成死信有以下幾種情況
消息被拒絕（basic.reject/basic.nack）並且requeue=false
消息TTL過期
隊列達到最大長度

死信隊列的特點
DLX也是一個正常的Exchange，和一般的Exchange沒有區別，它能在任何的隊列上被指定，實際上就是設置某個隊列的屬性；
當這個隊列中有死信時，RabbitMQ就會自動的將這個消息重新發布到設置的Exchange上去，進而被路由到另一個隊列；
可以監聽這個隊列中消息做相應的處理，這個特性可以彌補RabbitMQ3.0以前支持的immediate參數的功能；

死信隊列設置
首先需要設置死信隊列的Exchange和Queue，然後進行綁定：
Exchange：dlx.exchange
Queue：dlx.queue
RoutingKey：#
然後我們進行正常聲明交換機、隊列、綁定，只不過我們需要在隊列加上一個參數即可：
Arguments.put(“x-dead-letter-exchange”,”dlx.exchange”)；
這樣消息在過期、requeue、隊列在達到最大長度時，消息就可以直接路由到死信隊列！

自定義消費端

package com.tang.rabbitmqapi.dlx;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;

import java.io.IOException;

public class MyConsumer extends DefaultConsumer {


    public MyConsumer(Channel channel) {
        super(channel);
    }

    @Override
    public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
        System.err.println("-----------consume message----------");
        System.err.println("consumerTag: " + consumerTag);
        System.err.println("envelope: " + envelope);
        System.err.println("properties: " + properties);
        System.err.println("body: " + new String(body));
    }
}

消費端代碼

package com.tang.rabbitmqapi.dlx;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

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

public class Consumer {
    public static void main(String[] args) throws Exception {


        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.159.131");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();

        // 這就是一個普通的交換機 和 隊列 以及路由
        String exchangeName = "test_dlx_exchange";
        String routingKey = "dlx.#";
        String queueName = "test_dlx_queue";

        channel.exchangeDeclare(exchangeName, "topic", true, false, null);

        Map<String, Object> agruments = new HashMap<String, Object>();
        agruments.put("x-dead-letter-exchange", "dlx.exchange");
        //這個agruments屬性，要設置到聲明隊列上
        channel.queueDeclare(queueName, true, false, false, agruments);
        channel.queueBind(queueName, exchangeName, routingKey);

        //要進行死信隊列的聲明:
        channel.exchangeDeclare("dlx.exchange", "topic", true, false, null);
        channel.queueDeclare("dlx.queue", true, false, false, null);
        channel.queueBind("dlx.queue", "dlx.exchange", "#");

        channel.basicConsume(queueName, true, new MyConsumer(channel));

    }
}

生產端代碼

package com.tang.rabbitmqapi.dlx;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

public class Producer {
    public static void main(String[] args) throws Exception {

        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.159.131");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();

        String exchange = "test_dlx_exchange";
        String routingKey = "dlx.save";

        String msg = "Hello RabbitMQ DLX Message";

        for(int i =0; i<1; i ++){

            AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder()
                    .deliveryMode(2)
                    .contentEncoding("UTF-8")
                    .expiration("10000")
                    .build();
            channel.basicPublish(exchange, routingKey, true, properties, msg.getBytes());
        }

    }
}

測試（消息TTL過期）

當我們只啓動生產者

十秒後

限流及重回隊列及TTL消息及死信隊列

文章目錄

消費端限流

消息的ACK與重回隊列

TTL消息

死信隊列

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