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RabbitMQ之消息模式2

时间:2019-12-07 12:17:36      阅读:65      评论:0      收藏:0      [点我收藏+]

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消费端限流

什么是消费端的限流?

假设一个场景,首先,我们RabbitMQ服务器有上万条未处理的消息,我们随便打开一个消费者客户端,会出现下面情况:

巨量的消息瞬间全部推送过来,但是我们单个客户端无法同时处理这么多数据

 

消费端限流RabbitMQ提供的解决方案

RabbitMQ提供了一种qos(服务质量保证)功能,即在非自动确认消息的前提下,如果一定数目的消息(通过基于Consumer或者Channel设置Qos的值)未被确认前,不进行消费新的消息

Void BasicQos(uint prefetchSize, ushort prefetchCount, bool global);

prefetchSize:0      不限制消息大小

prefetchSize:会告诉RabbitMQ不要同时给一个消费者推送多于N个消息,即一旦有N个消息还没有ack,则该Consumer将block(阻塞)掉,直到有消息ack

Global:true\false是否将上面设置应用于Channel;简单来说,就是上面限制是Channel级别的还是Consumer级别

 

注意:

prefetchSize和global这两项,RabbitMQ没有实现,暂且不研究;

prefetch_count在no_ask=false的情况下生效,即在自动应答的情况下,这两个值是不生效的;

 

自定义消费端代码

package com.liuwenwu.rabbitmqaqi.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);
    }

}

消费端代码

package com.liuwenwu.rabbitmqaqi.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("192.168.241.134");
        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设置为 false
        channel.basicQos(0, 1, false);

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

提供方代码

package com.liuwenwu.rabbitmqaqi.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("192.168.241.134");
        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());
        }

    }
}

消息的ACK与重回队列

消费端手工ACK与NACK

消费端进行消费的时候,如果由于业务异常我们可以进行日志的记录,然后进行补偿

如果由于服务器宕机等严重问题,那么我们就需要手工进行ACK,保障消费端消费成功!

 

消费端的重回队列

消费端重回队列是为了对没有处理成功的消息,把消息重新回递给Broker!

一般我们在实际应用中,都会关闭重回队列,也就是设置为False;因为重回队列消息有很大概率依然会处理失败!

 

自定义消费者代码

package com.liuwenwu.rabbitmqaqi.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) {
//            手动签收,重回队列
            channel.basicNack(envelope.getDeliveryTag(), false, true);
        } else {
            channel.basicAck(envelope.getDeliveryTag(), false);
        }

    }
}

消费者代码

package com.liuwenwu.rabbitmqaqi.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("192.168.241.134");
        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);

        // 手工签收 必须要关闭 autoAck = false
        channel.basicConsume(queueName, false, new MyConsumer(channel));
    }
}

生产者代码

package com.liuwenwu.rabbitmqaqi.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("192.168.241.134");
        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());
        }
    }
}

TTL消息

TTL

TTL是Time To Live的缩写,也就是生存时间

RabbitMQ支持消息的过期时间,在消息发送时可以进行指定

RabbitMQ支持队列的过期时间,从消息入队列开始计算,只要超过了队列的超时时间配置,那么消息自动的清除

 

纯控制台操作(演示TTL队列消息特点)

针对队列,只要是这个队列的消息,就只有这么长的存活时间

 

注意:主要针对消息设置,跟交换机、队列、消费者设置毫无关系

 

消费端代码

package com.liuwenwu.rabbitmqaqi.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 创建一个ConnectionFactory, 并进行配置
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.241.134");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        //2 通过连接工厂创建连接
        Connection connection = connectionFactory.newConnection();

        //3 通过connection创建一个Channel
        Channel channel = connection.createChannel();

        //4 声明(创建)一个队列
        String queueName = "test001";
        channel.queueDeclare(queueName, true, false, false, null);

        //5 创建消费者
        QueueingConsumer queueingConsumer = new QueueingConsumer(channel);

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

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

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

    }
}

生产端代码

package com.liuwenwu.rabbitmqaqi.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 创建一个ConnectionFactory, 并进行配置
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.241.134");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        //2 通过连接工厂创建连接
        Connection connection = connectionFactory.newConnection();

        //3 通过connection创建一个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 通过Channel发送数据
        for(int i=0; i < 5; i++){
            String msg = "Hello RabbitMQ!";
            //1 exchange   2 routingKey
            channel.basicPublish("", "test001", properties, msg.getBytes());
        }

        //5 记得要关闭相关的连接
        channel.close();
        connection.close();
    }
}

死信队列

死信队列:DLX,Dead-Letter-Exchange

利用DLX,当消息在一个队列中变成死信(dead message)之后,它能被重新publish到另一个Exchange,这个Exchange就是DLX

 

消息变成死信有以下几种情况

  消息被拒绝(basic.reject/basic.nack)并且requeue=false

  消息TTL过期

  队列达到最大长度

 

死信队列的特点

  DLX也是一个正常的Exchange,和一般的Exchange没有区别,它能在任何的队列上被指定,实际上就是设置某个队列的属性;

  当这个队列中有死信时,RabbitMQ就会自动的将这个消息重新发布到设置的Exchange上去,进而被路由到另一个队列;

  可以监听这个队列中消息做相应的处理,这个特性可以弥补RabbitMQ3.0以前支持的immediate参数的功能;

 

死信队列设置

  首先需要设置死信队列的Exchange和Queue,然后进行绑定:

Exchange:dlx.exchange

Queue:dlx.queue

RoutingKey:#

  然后我们进行正常声明交换机、队列、绑定,只不过我们需要在队列加上一个参数即可:

Arguments.put(“x-dead-letter-exchange”,”dlx.exchange”);

  这样消息在过期、requeue、队列在达到最大长度时,消息就可以直接路由到死信队列!

技术图片

消息10s后还没有消费者消费,所以进入了死信队列

自定义消费端

package com.liuwenwu.rabbitmqaqi.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));
    }
}

消费端代码

package com.liuwenwu.rabbitmqaqi.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("192.168.241.134");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

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

        // 这就是一个普通的交换机 和 队列 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");
        //这个agruments属性,要设置到声明队列上
        channel.queueDeclare(queueName, true, false, false, agruments);
        channel.queueBind(queueName, exchangeName, routingKey);

        //要进行死信队列的声明:
        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));


    }
}

生产端代码

package com.liuwenwu.rabbitmqaqi.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("192.168.241.134");
        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());
        }

    }
}

 

RabbitMQ之消息模式2

标签:演示   xtend   cto   vat   code   ack   thread   string   content   

原文地址:https://www.cnblogs.com/liuwenwu9527/p/12001136.html

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