(Nacos源码解析四)Nacos服务健康检查源码解析

原创已于 2022-01-21 00:15:29 修改 · 682 阅读

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于 2021-10-19 17:16:22 首次发布

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本文详细解析Nacos服务健康检查的实现过程，涉及注册实例时创建心跳检查任务，检查中判断实例健康状态并处理超时和过期，以及自动删除未响应的服务实例。

Nacos源码解析系列目录

Nacos服务健康检查源码解析

概念

服务第一次注册的时候，开启对服务的定时检查客户端的健康状态

服务端

客户端调用服务端注册流程，可见
(Nacos源码解析一)Nacos 注册实例源码解析
com.alibaba.nacos.naming.controllers.InstanceController#register
com.alibaba.nacos.naming.core.ServiceManager#registerInstance
com.alibaba.nacos.naming.core.ServiceManager#createEmptyService
com.alibaba.nacos.naming.core.ServiceManager#createServiceIfAbsent
com.alibaba.nacos.naming.core.ServiceManager#putServiceAndInit
com.alibaba.nacos.naming.core.Service#init

1、创建客户端的心跳检查任务

 public void init() {
 //  GlobalExecutor.scheduleNamingHealth(task, 5000, 5000, TimeUnit.MILLISECONDS))
 //     默认每5s调度一次
        HealthCheckReactor.scheduleCheck(clientBeatCheckTask);
        for (Map.Entry<String, Cluster> entry : clusterMap.entrySet()) {
            entry.getValue().setService(this);
            entry.getValue().init();
        }
    }

2、心跳检查任务

com.alibaba.nacos.naming.healthcheck.ClientBeatCheckTask#run

@Override
public void run() {
    try {
        if (!getDistroMapper().responsible(service.getName())) {
            return;
        }
        
        if (!getSwitchDomain().isHealthCheckEnabled()) {
            return;
        }
        // 获取全部实例
        List<Instance> instances = service.allIPs(true);
        
        // first set health status of instances:
        for (Instance instance : instances) {
            // 当前时间 - 上一次心跳时间 > 心跳超时时间（默认15s）
            if (System.currentTimeMillis() - instance.getLastBeat() > instance.getInstanceHeartBeatTimeOut()) {
                if (!instance.isMarked()) {
                    if (instance.isHealthy()) {
                        // 标记为不健康状态
                        instance.setHealthy(false);
                        Loggers.EVT_LOG
                                .info("{POS} {IP-DISABLED} valid: {}:{}@{}@{}, region: {}, msg: client timeout after {}, last beat: {}",
                                        instance.getIp(), instance.getPort(), instance.getClusterName(),
                                        service.getName(), UtilsAndCommons.LOCALHOST_SITE,
                                        instance.getInstanceHeartBeatTimeOut(), instance.getLastBeat());
                        getPushService().serviceChanged(service);
                        ApplicationUtils.publishEvent(new InstanceHeartbeatTimeoutEvent(this, instance));
                    }
                }
            }
        }
        
        if (!getGlobalConfig().isExpireInstance()) {
            return;
        }
        
        // then remove obsolete instances:
        for (Instance instance : instances) {
            
            if (instance.isMarked()) {
                continue;
            }
            // 当前时间 - 上一次心跳时间 > 实例删除时间(默认30s)
            if (System.currentTimeMillis() - instance.getLastBeat() > instance.getIpDeleteTimeout()) {
                // delete instance
                Loggers.SRV_LOG.info("[AUTO-DELETE-IP] service: {}, ip: {}", service.getName(),
                        JacksonUtils.toJson(instance));
                // 删除实例
                deleteIp(instance);
            }
        }
        
    } catch (Exception e) {
        Loggers.SRV_LOG.warn("Exception while processing client beat time out.", e);
    }
    
}

3、删除实例

com.alibaba.nacos.naming.healthcheck.ClientBeatCheckTask#deleteIp

private void deleteIp(Instance instance) {
    
    try {
        NamingProxy.Request request = NamingProxy.Request.newRequest();
        // 封装删除实例的信息
        request.appendParam("ip", instance.getIp()).appendParam("port", String.valueOf(instance.getPort()))
                .appendParam("ephemeral", "true").appendParam("clusterName", instance.getClusterName())
                .appendParam("serviceName", service.getName()).appendParam("namespaceId", service.getNamespaceId());
        
        String url = "http://" + IPUtil.localHostIP() + IPUtil.IP_PORT_SPLITER + EnvUtil.getPort() + EnvUtil.getContextPath()
                + UtilsAndCommons.NACOS_NAMING_CONTEXT + "/instance?" + request.toUrl();
        
        ....
        
    } catch (Exception e) {
        Loggers.SRV_LOG
                .error("[IP-DEAD] failed to delete ip automatically, ip: {}, error: {}", instance.toJson(), e);
    }
}

4、调用服务下线方法

com.alibaba.nacos.naming.controllers.InstanceController#deregister
com.alibaba.nacos.naming.core.ServiceManager#removeInstance(java.lang.String, java.lang.String, boolean, com.alibaba.nacos.naming.core.Instance…)

private void removeInstance(String namespaceId, String serviceName, boolean ephemeral, Service service,
        Instance... ips) throws NacosException {
    
    String key = KeyBuilder.buildInstanceListKey(namespaceId, serviceName, ephemeral);
    // 更新instanceMap
    List<Instance> instanceList = substractIpAddresses(service, ephemeral, ips);
    
    Instances instances = new Instances();
    instances.setInstanceList(instanceList);
    // 将注册实例更新到内存注册表并同步到集群其他节点
    consistencyService.put(key, instances);
}