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微架构 springcloud-10. Eureka 心跳管理

微架构 springcloud-10. Eureka 心跳管理

作者: 程序员_超 | 来源:发表于2018-03-21 14:44 被阅读0次

    常见配置

    心跳检测

    客户端(Client)：

    1. 注册服务收起发送:>> 每隔n（n=30,默认）秒向Eureka服务端发送信息，刷新注册服务，
    2. 客户端告知服务端：若在n秒内没有向服务器发送信息，则服务端将其从服务列表中删除

    客户端添加如下配置：

    #客户端每隔n秒向服务端发送数据包
eureka.instance.leaseRenewalIntervalInSeconds=5
#客户端告知服务端：若在n秒内没有向服务器发送信息，则服务端将其从服务列表中删除
eureka.instance.leaseExpirationDurationInSeconds=10
#配置日志级别
logging.level.com.netflix:DEBUG

    服务端(Server):

    1. 关闭自我保护
    2. 注册服务周期检测:>> 每隔n(n=90,默认)秒检测服务端是否重新注册服务，否则将服务从服务列表中清除

    相关配置如下：

    #关闭Eureka服务自我保护
eureka.server.enable-self-preservation=false
#服务端每隔n秒刷新依次服务列表，将无效服务剔除
eureka.server.eviction-interval-timer-in-ms=5000

    接下来做的都是单节点测试，故关闭Eureka作为客户端相关的配置，否则启动会报错:

    #eureka.client.service-url.defaultZone=http://localhost:8762/eureka/
# 关闭默认注册到eureka服务中心（该项目本身就是服务中心，无需自己注册自己）
eureka.client.register-with-eureka=false
# 关闭自动抓取服务端，该工程本身就是服务端
eureka.client.fetch-registry=false

    重启Eureka服务 8761：

    2018-03-16 11:47:38.507 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Get connection: {}->http://localhost:8761, timeout = 5000
2018-03-16 11:47:38.507 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : [{}->http://localhost:8761] total kept alive: 1, total issued: 0, total allocated: 1 out of 200
2018-03-16 11:47:38.507 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Getting free connection [{}->http://localhost:8761][null]
2018-03-16 11:47:38.515 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Released connection is reusable.
2018-03-16 11:47:38.515 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Releasing connection [{}->http://localhost:8761][null]
2018-03-16 11:47:38.515 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Pooling connection [{}->http://localhost:8761][null]; keep alive indefinitely
2018-03-16 11:47:38.515 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Notifying no-one, there are no waiting threads
2018-03-16 11:47:38.515 DEBUG 70716 --- [tbeatExecutor-0] n.d.s.t.j.AbstractJerseyEurekaHttpClient : Jersey HTTP PUT http://localhost:8761/eureka//apps/APPTWO/192.168.198.2:AppTwo:8083; statusCode=200
2018-03-16 11:47:38.516 DEBUG 70716 --- [tbeatExecutor-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_APPTWO/192.168.198.2:AppTwo:8083 - Heartbeat status: 200
2018-03-16 11:47:43.519 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Get connection: {}->http://localhost:8761, timeout = 5000
2018-03-16 11:47:43.519 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : [{}->http://localhost:8761] total kept alive: 1, total issued: 0, total allocated: 1 out of 200
2018-03-16 11:47:43.519 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Getting free connection [{}->http://localhost:8761][null]
2018-03-16 11:47:43.528 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Released connection is reusable.
2018-03-16 11:47:43.529 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Releasing connection [{}->http://localhost:8761][null]
2018-03-16 11:47:43.529 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Pooling connection [{}->http://localhost:8761][null]; keep alive indefinitely
2018-03-16 11:47:43.529 DEBUG 70716 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Notifying no-one, there are no waiting threads
2018-03-16 11:47:43.529 DEBUG 70716 --- [tbeatExecutor-0] n.d.s.t.j.AbstractJerseyEurekaHttpClient : Jersey HTTP PUT http://localhost:8761/eureka//apps/APPTWO/192.168.198.2:AppTwo:8083; statusCode=200
2018-03-16 11:47:43.529 DEBUG 70716 --- [tbeatExecutor-0] com.netflix.discovery.DiscoveryClient 

## 服务端每隔5秒刷新服务列表
2018-03-19 15:44:05.760  INFO 17660 --- [a-EvictionTimer] c.n.e.registry.AbstractInstanceRegistry  : Running the evict task with compensationTime 0ms
2018-03-19 15:44:10.761  INFO 17660 --- [a-EvictionTimer] c.n.e.registry.AbstractInstanceRegistry  : Running the evict task with compensationTime 0ms

    重启客户端服务 8081：

    2018-03-20 15:51:15.353 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Get connection: {}->http://localhost:8761, timeout = 5000
2018-03-20 15:51:15.353 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : [{}->http://localhost:8761] total kept alive: 1, total issued: 0, total allocated: 1 out of 200
2018-03-20 15:51:15.353 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Getting free connection [{}->http://localhost:8761][null]
2018-03-20 15:51:15.356 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Released connection is reusable.
2018-03-20 15:51:15.356 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Releasing connection [{}->http://localhost:8761][null]
2018-03-20 15:51:15.357 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Pooling connection [{}->http://localhost:8761][null]; keep alive indefinitely
2018-03-20 15:51:15.357 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Notifying no-one, there are no waiting threads
2018-03-20 15:51:15.357 DEBUG 15556 --- [tbeatExecutor-0] n.d.s.t.j.AbstractJerseyEurekaHttpClient : Jersey HTTP PUT http://localhost:8761/eureka//apps/APPONE/192.168.198.2:AppOne:8081; statusCode=200
2018-03-20 15:51:15.357 DEBUG 15556 --- [tbeatExecutor-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_APPONE/192.168.198.2:AppOne:8081 - Heartbeat status: 200


2018-03-20 15:51:20.358 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Get connection: {}->http://localhost:8761, timeout = 5000
2018-03-20 15:51:20.358 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : [{}->http://localhost:8761] total kept alive: 1, total issued: 0, total allocated: 1 out of 200
2018-03-20 15:51:20.358 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Getting free connection [{}->http://localhost:8761][null]
2018-03-20 15:51:20.361 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Released connection is reusable.
2018-03-20 15:51:20.361 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Releasing connection [{}->http://localhost:8761][null]
2018-03-20 15:51:20.361 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Pooling connection [{}->http://localhost:8761][null]; keep alive indefinitely
2018-03-20 15:51:20.361 DEBUG 15556 --- [tbeatExecutor-0] c.n.d.shared.NamedConnectionPool         : Notifying no-one, there are no waiting threads
2018-03-20 15:51:20.361 DEBUG 15556 --- [tbeatExecutor-0] n.d.s.t.j.AbstractJerseyEurekaHttpClient : Jersey HTTP PUT http://localhost:8761/eureka//apps/APPONE/192.168.198.2:AppOne:8081; statusCode=200
2018-03-20 15:51:20.361 DEBUG 15556 --- [tbeatExecutor-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_APPONE/192.168.198.2:AppOne:8081 - Heartbeat status: 200


客户端每隔5秒向服务端发送信息！

    强制停止客户端，查看服务端信息，打印：

    2018-03-20 15:51:43.523  INFO 13276 --- [a-EvictionTimer] c.n.e.registry.AbstractInstanceRegistry  : Evicting 1 items (expired=1, evictionLimit=1)
2018-03-20 15:51:43.523  WARN 13276 --- [a-EvictionTimer] c.n.e.registry.AbstractInstanceRegistry  : DS: Registry: expired lease for APPONE/192.168.198.2:AppOne:8081
2018-03-20 15:51:43.524  INFO 13276 --- [a-EvictionTimer] c.n.e.registry.AbstractInstanceRegistry  : Cancelled instance APPONE/192.168.198.2:AppOne:8081 (replication=false)

服务端已将无效服务 AppOne:8081 剔除出服务列表

    一个客户端（App2）要访问另一个客户端（App1）的服务，App2在启动过程中就会首先读取服务列表，将App1服务存储到自己（App2）上，App2 访问时则根据此路由访问App1的服务，那么App2如何确保App1服务一直是有效的呢？比如App1异常中断服务；所以，各App本身也会定时的向Eureka确认，刷新自己的可用的服务列表，默认是每隔 30s 向Eureka服务中心确认，此配置更改如下：

    # 定时的向Eureka确认，刷新自己的可用的服务列表，修改为5s
eureka.client.registry-fetch-interval-seconds=5

#将原有注册相关配置时间间隔增大：

# 客户端每隔n秒向服务端发送数据包
eureka.instance.leaseRenewalIntervalInSeconds=60
# 客户端告知服务端：若在n秒内没有向服务器发送信息，则服务端将其从服务列表中删除
eureka.instance.leaseExpirationDurationInSeconds=600

    重启App2，后台会没间隔5秒打印打印如下信息：

    2018-03-21 09:42:59.080 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Get connection: {}->http://localhost:8761, timeout = 5000
2018-03-21 09:42:59.080 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.NamedConnectionPool         : [{}->http://localhost:8761] total kept alive: 1, total issued: 0, total allocated: 1 out of 200
2018-03-21 09:42:59.080 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.NamedConnectionPool         : Getting free connection [{}->http://localhost:8761][null]
2018-03-21 09:42:59.085 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Released connection is reusable.
2018-03-21 09:42:59.085 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.NamedConnectionPool         : Releasing connection [{}->http://localhost:8761][null]
2018-03-21 09:42:59.085 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.NamedConnectionPool         : Pooling connection [{}->http://localhost:8761][null]; keep alive indefinitely
2018-03-21 09:42:59.085 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.NamedConnectionPool         : Notifying no-one, there are no waiting threads
2018-03-21 09:42:59.085 DEBUG 19496 --- [freshExecutor-0] n.d.s.t.j.AbstractJerseyEurekaHttpClient : Jersey HTTP GET http://localhost:8761/eureka//apps/delta?; statusCode=200
2018-03-21 09:42:59.085 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : Got delta update with apps hashcode UP_1_
2018-03-21 09:42:59.085 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : Added instance 192.168.198.2:AppTwo:8083 to the existing apps in region null
2018-03-21 09:42:59.085 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : Deleted instance 192.168.198.2:AppOne:8081 to the existing apps 
2018-03-21 09:42:59.085 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : The total number of instances fetched by the delta processor : 2
2018-03-21 09:42:59.085 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : The total number of all instances in the client now is 1
2018-03-21 09:42:59.086 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : Completed cache refresh task for discovery. All Apps hash code is Local region apps hashcode: UP_1_, is fetching remote regions? false 



2018-03-21 09:43:04.087 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Get connection: {}->http://localhost:8761, timeout = 5000
2018-03-21 09:43:04.087 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.NamedConnectionPool         : [{}->http://localhost:8761] total kept alive: 1, total issued: 0, total allocated: 1 out of 200
2018-03-21 09:43:04.087 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.NamedConnectionPool         : Getting free connection [{}->http://localhost:8761][null]
2018-03-21 09:43:04.091 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.MonitoredConnectionManager  : Released connection is reusable.
2018-03-21 09:43:04.091 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.NamedConnectionPool         : Releasing connection [{}->http://localhost:8761][null]
2018-03-21 09:43:04.091 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.NamedConnectionPool         : Pooling connection [{}->http://localhost:8761][null]; keep alive indefinitely
2018-03-21 09:43:04.091 DEBUG 19496 --- [freshExecutor-0] c.n.d.shared.NamedConnectionPool         : Notifying no-one, there are no waiting threads
2018-03-21 09:43:04.091 DEBUG 19496 --- [freshExecutor-0] n.d.s.t.j.AbstractJerseyEurekaHttpClient : Jersey HTTP GET http://localhost:8761/eureka//apps/delta?; statusCode=200
2018-03-21 09:43:04.091 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : Got delta update with apps hashcode UP_1_
2018-03-21 09:43:04.091 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : Deleted instance 192.168.198.2:AppOne:8081 to the existing apps 
2018-03-21 09:43:04.091 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : The total number of instances fetched by the delta processor : 1
2018-03-21 09:43:04.091 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : The total number of all instances in the client now is 1
2018-03-21 09:43:04.091 DEBUG 19496 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : Completed cache refresh task for discovery. All Apps hash code is Local region apps hashcode: UP_1_, is fetching remote regions? false

    将App1 /sayMesg/{word} 业务逻辑代码更改如下：

    @RequestMapping(value = "/sayMesg/{word}")
public @ResponseBody String sayMesg(@PathVariable String word){
    if(word==null){
        return "未接收到参数！";
    }
    StringBuffer buffer = new StringBuffer();
    for (int i = 0; i < word.length(); i++) {
        int acii = word.charAt(i);
        buffer.append(acii + ",");
    }
    return active + buffer.toString() ;
}

# 即返回参数world 的Ascii码

    回顾App2 /getAppOneMesg/{mesg} 代码：

    @RequestMapping("/getAppOneMesg/{mesg}")
public @ResponseBody String getAppOneMesg(@PathVariable String mesg){
    String strMesg=restTemplate.getForObject("http://APPONE/sayMesg/" + mesg, String.class);
    return "访问App2,从App1 收到信息：“"+strMesg+"”";
}

    重新梳理逻辑：重启Eureka、App1、App2,待启动完成，访问 http://192.168.198.2:8083/getAppOneMesg/123456，页面打印：

    访问App2,从App1 收到信息：“808149,50,51,52,53,54,“

    强制停止App1服务，观察App2 控制台：

    ##其中打印：
2018-03-21 10:33:24.061 DEBUG 6636 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : Deleted instance 192.168.198.2:AppOne:8081 to the existing apps 

App1 服务停止，那么Eureka服务端在扫描规则下会将App1从服务列表中剔除，App2 刷新本地服务列表，将不存在于服务端的App1从本地剔除

    再访问：http://192.168.198.2:8083/getAppOneMesg/123456，页面打印：

    Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Wed Mar 21 10:36:43 CST 2018
There was an unexpected error (type=Internal Server Error, status=500).
No instances available for APPONE

# App1 已经停止服务，且本地（App2）已剔除该服务信息，故无法访问

    重启App1,观察App2 客户端：

    # 其中打印
2018-03-21 10:39:07.162 DEBUG 21960 --- [freshExecutor-0] com.netflix.discovery.DiscoveryClient    : Added instance 192.168.198.2:AppOne:8081 to the existing apps in region null

# 说明App2已经将App1服务添加到本地

    再访问：http://192.168.198.2:8083/getAppOneMesg/123456，页面打印：

    访问App2,从App1 收到信息：“808149,50,51,52,53,54,“

# 应用恢复正常

    客户端获取本地服务信息，以下示例以App2为列

    1. 注入DiscoveryClient
    @Autowired
private DiscoveryClient discoveryClient;
    1. 获取服务名称，即：App1、App2
    @GetMapping("/discoveryClientList")
public List discoveryClientList(){
    /*获取Eureka 中的服务名称列表*/
    List<String> services = discoveryClient.getServices();
    return services;
}
    1. 获取服务具体实例
    @GetMapping("/discoveryClientInstanceList")
public List<Map> discoveryClientInstanceList(){
    /*获取客户端实例列表*/

    List<Map> list = new ArrayList<Map>();
    Map<String, Object> map = new HashMap<String, Object>();
    List<String> servicesNames = discoveryClient.getServices(); //获取名称
    for (String name : servicesNames) {
        map = new HashMap<String, Object>();
        List<ServiceInstance> instanceList = discoveryClient.getInstances(name);
        Map objs = new HashMap();
        for (ServiceInstance instance : instanceList) {
            objs.put("host", instance.getHost());
            objs.put("port", instance.getPort());
            objs.put("serviceId",instance.getServiceId());
            objs.put("uri", instance.getUri());
        }
        map.put(name, objs);
        list.add(map);
    }
    return list;
}

    访问：http://192.168.198.2:8083/discoveryClientList 页面响应：

    ["appone","apptwo"]

# 只是服务名

    访问：http://192.168.198.2:8083/discoveryClientInstanceList 页面响应：

    [
    {"appone":{"port":8081,"host":"192.168.198.2","serviceId":"APPONE","uri":"http://192.168.198.2:8081"}},
    {"apptwo":{"port":8083,"host":"192.168.198.2","serviceId":"APPTWO","uri":"http://192.168.198.2:8083"}}
]

# 各服务名实例包括：端口、地址、ID、URI 等

    配置元数据，App2 配置文件添加如下配置：

    # 配置元数据：metadata
eureka.instance.metadata-map.companename:PersonJack
eureka.instance.metadata-map.address:chongqing

    从DiscoveryClient 获取元数据，其实也是从ServiceInstance 中获取的，配置文件中spring.application.name即为实例名，故相关Controller 书写如下：

    @GetMapping("/metaMap")
public @ResponseBody List metaMap(){
    List<ServiceInstance> instanceList = discoveryClient.getInstances("AppTwo");
    List list = new ArrayList();
    for (ServiceInstance instance : instanceList) {
        Map map=instance.getMetadata();
        list.add(map);
    }
    return list;
}

    访问：http://192.168.198.2:8083/metaMap 页面响应如下：

    [{"companename":"PersonJack","address":"chongqing"}]

# 元数据成功获取

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