从零开始教你dubbo自定义负载均衡策略

傷城~ 2023-02-18 08:14 133阅读 0赞

前言：官网文档有一重要章节[SPI][]，建立好好阅读，为本文做铺垫

1.搭建工程,结构如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDcwMzkz_size_16_color_FFFFFF_t_70][]

dubbo-learn                ---> 父pom

dubbo-api                   ---> 服务提供者和消费者共同依赖对接口api

dubbo-provide1,2,3    ---> 分别是3个服务提供者

dubbo-consumer        ---> 服务消费者

1.1) dubbo-learn对应pom

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.3.1.RELEASE</version>
            <relativePath/> 
        </parent>
    
        <groupId>org.example</groupId>
        <artifactId>dubbo-learn</artifactId>
        <version>1.0.0</version>
        <packaging>pom</packaging>
    
        <modules>
            <module>dubbo-provide1</module>
            <module>dubbo-provide2</module>
            <module>dubbo-provide3</module>
            <module>dubbo-consumer</module>
            
        </modules>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-redis</artifactId>
                <version>2.3.1.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo-spring-boot-starter</artifactId>
                <version>2.7.6</version>
                <scope>compile</scope>
            </dependency>
            
            <dependency>
                <groupId>redis.clients</groupId>
                <artifactId>jedis</artifactId>
                <version>2.8.1</version>
                <scope>compile</scope>
            </dependency>
            <dependency>
                <groupId>com.example</groupId>
                <artifactId>dubbo-api</artifactId>
                <version>1.0.0</version>
            </dependency>
        </dependencies>
    </project>

1.2) dubbo-api层pom

1.3) dubbo-consumer层pom

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <parent>
            <groupId>org.example</groupId>
            <artifactId>dubbo-learn</artifactId>
            <version>1.0.0</version>
        </parent>
    
        <artifactId>dubbo-consumer</artifactId>
        <name>dubbo-consumer</name>
        <description>Demo project for Spring Boot</description>
    
        <properties>
            <java.version>1.8</java.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-aop</artifactId>
                <version>2.2.6.RELEASE</version>
            </dependency>
    
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
    </project>

1.4) dubbo-privode1,2,3对应pom一样,如下：

1.5)dubbo-consumer 配置文件application.yml

dubbo:
      scan:
        base-packages: com.example.dubbo
      registry:
        protocol: redis
        parameters:
          # 指定redis数据库，别问我为什么是这个参数，看源码发现的
          db.index: 15
        # 上面配置了redis故直接取值即可，也可以直接写成 address: root:123456@127.0.0.1:6379
        address: root:${spring.redis.password}@${spring.redis.host}:${spring.redis.port}
        cluster: failover
      protocol:
        # 名字任意
        id: dubbo-executor
        port: 20880
        name: cust
      application:
        # 名字任意
        name: consumer
      consumer:
        # 自定义调用提供者负载均衡模式，再未进行自定义的情况下先注释
        # loadbalance: cust
    spring:
      redis:
        host: 127.0.0.1
        password: 123456
        port: 6379
        database: 3
    server:
      port: 12000

1.6)dubbo-provide1,2,3 对应pom文件，注意修改端口号

dubbo:
      scan:
        base-packages: com.example.dubbo
      registry:
        protocol: redis
        parameters:
          # 指定redis数据库，别问我为什么是这个参数，看源码发现的
          db.index: 15
        # 上面配置了redis故直接取值即可，也可以直接写成 address: root:123456@127.0.0.1:6379
        address: root:${spring.redis.password}@${spring.redis.host}:${spring.redis.port}
        cluster: failover
      protocol:
        # 名字任意
        id: dubbo-executor
        port: 20881
        name: dubbo
      application:
        # 名字任意
        name: provide1
    
    spring:
      redis:
        host: 127.0.0.1
        password: 123456
        port: 6379
        database: 3
    server:
      port: 12001

笔者是本地测试，因此需要修改这2处

注意：provide1,2,3配置文件有2处需要修改端口号，1)dubbo.protocol.port: xxx ; 2) server.port: xxx ;

1.7）分别在各个模块入口类在添加注解 @EnableDubbo

示例：![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDcwMzkz_size_16_color_FFFFFF_t_70 1][]

2.在dubbo-api层新建接口

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDcwMzkz_size_16_color_FFFFFF_t_70 2][]

3.在dubbo-provide1,2,3模块中分别实现该接口

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDcwMzkz_size_16_color_FFFFFF_t_70 3][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDcwMzkz_size_16_color_FFFFFF_t_70 4][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDcwMzkz_size_16_color_FFFFFF_t_70 5][]

4.dubbo-consumer写一个消费接口

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDcwMzkz_size_16_color_FFFFFF_t_70 6][]

以上就已经完成了一个消费者对应多个提供者骨架，

编译顺序

1)dubbo-api      ---> clear install

2)dubbo-learn  ---> clear install

启动顺序是：

1）启动redis

2）启动dubbo-provide1,2,3

3)启动dubbo-consumer

4）测试

5.自定义负载均衡策略

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDcwMzkz_size_16_color_FFFFFF_t_70 7][]

说明：第4步再建一层dubbo文件夹时，其实也可以建一个名为services文件夹，效果是一样的

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDcwMzkz_size_16_color_FFFFFF_t_70 8][]

在新建的纯文本文件里输入：

cust=com.example.dubbo.balance.CustomLoadBalance

格式：别名=自定义类全类名

6.修改dubbo-consumer配置，

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDcwMzkz_size_16_color_FFFFFF_t_70 9][]

完成，进行测试。

遇到的问题：

1）dubbo版本对应的jedis不应太高，否则会报错找不到redis/clients/util/Pool

解决办法：降低jedis版本到2.8.1（2.8.0也行自行选择，不要高于2.9.0）

2)自定义负载均衡不生效

可能原因：

a)可能是文件层级不对，应该分开建META-INF,在建dubbo文件夹

b)配置错误，在消费端配置调用到提供端负载，应该配置dubbo.consumer.loadbalance,而不是配置dubbo.provider.loadbalance

写的很乱有问题可以留言，看到后会回复

学习源码在gitee上：[https://gitee.com/vick-chow/dubbo-learn.git][https_gitee.com_vick-chow_dubbo-learn.git]

[SPI]: http://dubbo.apache.org/zh-cn/docs/dev/SPI.html
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[https_gitee.com_vick-chow_dubbo-learn.git]: https://gitee.com/vick-chow/dubbo-learn.git