一、Ribbon中的负载均衡策略
1、Ribbon中支持的负载均衡策略
AvailabilityFilteringRule：过滤掉那些因为一直连接失败的被标记为circuit tripped的后端server，并过滤掉那些高并发的的后端server（active connections 超过配置的阈值） | 使用一个AvailabilityPredicate来包含过滤server的逻辑，其实就就是检查status里记录的各个server的运行状态
RandomRule：随机选择一个server
BestAvailabl：选择一个最小的并发请求的server，逐个考察Server，如果Server被tripped了，则忽略
RoundRobinRule：roundRobin方式轮询选择， 轮询index，选择index对应位置的server
WeightedResponseTimeRule：根据响应时间分配一个weight(权重)，响应时间越长，weight越小，被选中的可能性越低
RetryRule：对选定的负载均衡策略机上重试机制，在一个配置时间段内当选择server不成功，则一直尝试使用subRule的方式选择一个可用的server
ZoneAvoidanceRule：复合判断server所在区域的性能和server的可用性选择server
ResponseTimeWeightedRule：作用同WeightedResponseTimeRule，二者作用是一样的，ResponseTimeWeightedRule后来改名为WeightedResponseTimeRule
二、验证
1、自定义负载均衡策略
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# 自定义负载均衡策略 springboot-h2.ribbon.NFLoadBalancerRuleClassName=com.netflix.loadbalancer.RandomRule // 自定义使用随机策略，springboot-h2是服务应用名
2、修改调用代码
package com.chhliu.springboot.restful.controller; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.cloud.client.ServiceInstance; import org.springframework.cloud.client.loadbalancer.LoadBalancerClient; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.client.RestTemplate; import com.chhliu.springboot.restful.vo.User; @RestController public class RestTemplateController { @Autowired private RestTemplate restTemplate; @Autowired private LoadBalancerClient loadBalancerClient; @GetMapping("/template/{id}") public User findById(@PathVariable Long id) { ServiceInstance serviceInstance = this.loadBalancerClient.choose("springboot-h2"); System.out.println("===" + ":" + serviceInstance.getServiceId() + ":" + serviceInstance.getHost() + ":" + serviceInstance.getPort());// 打印当前调用服务的信息 User u = this.restTemplate.getForObject("http://springboot-h2/user/" + id, User.class); System.out.println(u); return u; } }
3、测试
服务调用关系如下：
测试结果如下：
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===:springboot-h2:127.0.0.1:7902 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7901 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7902 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7901 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7902 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7902 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7902 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7902 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7902 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7901 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7901 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7902 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7902 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7901 User [id=2, username=user2, name=李四, age=20, balance=100.00] ===:springboot-h2:127.0.0.1:7901 User [id=2, username=user2, name=李四, age=20, balance=100.00] 发现选择7901端口服务和7902端口服务确实是随机的！
