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故事背景 jenkins部署时总是会有几秒钟接口调用报错#xff0c;观察日志是因为流量被下发到已下线的服务#xff0c;重启脚本在停止应用之前先调用nacos注销实例api后再重启依然会短暂出现此问题。项目架构是springcloud alibaba,通过openfeign进行微服务之间调用…前言
故事背景 jenkins部署时总是会有几秒钟接口调用报错观察日志是因为流量被下发到已下线的服务重启脚本在停止应用之前先调用nacos注销实例api后再重启依然会短暂出现此问题。项目架构是springcloud alibaba,通过openfeign进行微服务之间调用猜测是LoadBalancer缓存问题。依赖版本
dependencyManagementdependenciesdependencygroupIdcom.alibaba.cloud/groupIdartifactIdspring-cloud-alibaba-dependencies/artifactIdversion2021.0.1.0/versiontypepom/typescopeimport/scope/dependencydependencygroupIdorg.springframework.boot/groupIdartifactIdspring-boot-dependencies/artifactIdversion2.6.3/versiontypepom/typescopeimport/scope/dependencydependencygroupIdorg.springframework.cloud/groupIdartifactIdspring-cloud-dependencies/artifactIdversion2021.0.1/versiontypepom/typescopeimport/scope/dependency/dependencies
/dependencyManagementdependenciesdependencygroupIdcom.alibaba.cloud/groupIdartifactIdspring-cloud-starter-alibaba-nacos-discovery/artifactIdexclusionsexclusiongroupIdorg.springframework.cloud/groupIdartifactIdspring-cloud-starter-netflix-ribbon/artifactId/exclusion/exclusions/dependencydependencygroupIdorg.springframework.cloud/groupIdartifactIdspring-cloud-starter-openfeign/artifactIdversion3.1.1/version/dependency
/dependenciesloadbalancer配置
spring:cloud:loadbalancer:#需要引入Spring Retry依赖retry:enabled: truespringcloud loadbalancer缓存原理 启用启动首先装配Caffeine一级缓存缓存应用实例降低注册中心负载提升性能 从上图可以看出可以通过设置spring.cloud.loadbalancer.cache来关闭一级缓存其值默认是开启的。 feign初次从loadbalance获取应用实例会触发装配ServiceInstanceListSupplier逻辑
从一级缓存中获取应用实例: 解决方案
通过上面的源码分析根本原因是应用从nacos下线后loadbalancer的一级缓存未移除下线实例有以下解决办法:
重启脚本下线nacos实例后等待一级缓存失效后(默认35s)再重启应用禁用一级缓存不建议监听nacos下线事件手动移除实例
方案实现
采用方案 监听nacos下线事件手动移除实例代码实现 思路 nacos订阅需要删除缓存的服务名(serviceName)下线应用主动调用nacos实例注销api后由nacos server触发自定义的订阅回调逻辑nacos订阅源码分析
从上图可以看出默认只会订阅当前服务名这也是为什么以下代码在其他应用主动下线后没有触发回调的原因 - 编写指定服务nacos订阅与删除实例缓存逻辑
package com.xxx.xxx.feign.listener;import com.alibaba.cloud.nacos.NacosDiscoveryProperties;
import com.alibaba.cloud.nacos.NacosServiceManager;
import com.alibaba.nacos.api.naming.NamingService;
import com.alibaba.nacos.api.naming.listener.NamingEvent;
import lombok.SneakyThrows;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.cache.Cache;
import org.springframework.cloud.loadbalancer.cache.LoadBalancerCacheManager;
import org.springframework.cloud.loadbalancer.cache.LoadBalancerCacheProperties;
import org.springframework.cloud.loadbalancer.core.CachingServiceInstanceListSupplier;
import org.springframework.context.annotation.Configuration;import javax.annotation.Resource;
import java.util.Arrays;/*** description nacos应用监听* date 2024/7/29*/
Configuration
ConditionalOnProperty(name spring.cloud.loadbalancer.cache.enabled, havingValue true)
AutoConfigureAfter(LoadBalancerCacheProperties.class)
public class NacosInstanceListener implements InitializingBean {Resourceprivate NacosServiceManager nacosServiceManager;Resourceprivate NacosDiscoveryProperties properties;Resourceprivate LoadBalancerCacheManager caffeineLoadBalancerCacheManager;OverrideSneakyThrowspublic void afterPropertiesSet() {NamingService namingService nacosServiceManager.getNamingService(properties.getNacosProperties());namingService.subscribe(xxx-product-xxx, properties.getGroup(), Arrays.asList(properties.getClusterName()), event - {if (event instanceof NamingEvent) {NamingEvent namingEvent (NamingEvent) event;String svrName namingEvent.getServiceName();Cache cache caffeineLoadBalancerCacheManager.getCache(CachingServiceInstanceListSupplier.SERVICE_INSTANCE_CACHE_NAME);if (cache ! null) {cache.evict(svrName);}System.out.println(event);}});}
}下线服务主动调用nacos注销实例接口观察效果 从上图可以看到删除服务实例缓存回调成功触发考虑到调用nacos api下线到上述代码被成功执行的耗时应用重启脚本最好在调用nacos api成功后等待1秒左右再停止服务。
