SpringCloud Alibaba Sentinel实现熔断与限流

服务使用中的各种问题 

  服务雪崩
  服务降级
  服务熔断
  服务限流

安装Sentinel 

sentinel和项目必须在同一个ip下

  sentinel组件由2部分构成
    后台
    前台8080
    运行命令
      前提
        java8环境OK
        8080端口不能被占用
      命令
        java -jar sentinel-dashboard-1.7.1.jar
    访问sentinel管理界面
      http://localhost:8080
      登录账户密码均为 sentinel 

初始化演示工程

启动Nacos8848成功
    http://localhost:8848/nacos/#/login
  创建Module    cloudalibaba-sentinel-service8401
    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"><parent><artifactId>wms</artifactId><groupId>com.hk.wms</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>wms-sentinel-service8401</artifactId>
<dependencies><!-- SpringCloud ailibaba nacos--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!-- SpringCloud ailibaba sentinel-datasource-nacos 持久化需要用到--><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-datasource-nacos</artifactId></dependency><!-- SpringCloud ailibaba sentinel--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!--监控--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><!--热部署--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><scope>runtime</scope><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency>
</dependencies>
</project>

    YML

server:port: 8401spring:application:name: wms-sentinal-servicecloud:nacos:discovery:#Nacos服务注册中心地址server-addr: 192.168.1.131:8848sentinel:transport:#配置Sentin dashboard地址dashboard: localhost:8080# 默认8719端口，假如被占用了会自动从8719端口+1进行扫描，直到找到未被占用的 端口port: 8719
service-url:nacos-user-service: http://wms-provider
config-url:config-service: http://wms-config-3377management:endpoints:web:exposure:include: '*'

    主启动

package com.hk.wms.wmssentinelservice8401;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;@SpringBootApplication
@EnableDiscoveryClient
public class WmsSentinelService8401Application {public static void main(String[] args) {SpringApplication.run(WmsSentinelService8401Application.class, args);}}

    业务类FlowLimitController

package com.hk.wms.wmssentinelservice8401.controller;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
@RestController
public class FlowLimitController {@Value("${service-url.nacos-user-service}")String serverUrl ;@Value("${config-url.config-service}")String configUrl;@AutowiredRestTemplate template;@GetMapping("/testA")public String testA() {return "----testA";}@GetMapping("/testB")public String testB() {return "----testB";}@GetMapping("/testC")public String testC() {return template.getForObject(serverUrl+"/provider/",String.class);}
}

  启动Sentinel8080
  启动微服务8401
    空空如也
    Sentinel采用的懒加载说明
      执行一次访问即可
        http://localhost:8401/testA
        http://localhost:8401/testB
      sentinel8080正在监控微服务8401 

sentinel和项目必须在同一个ip下，sentinel才能监控微服务端口8401

流控规则

基本介绍
    进一步解释说明

  流控模式
    直接（默认）
      直接-> 快速失败
        默认
      配置及说明

      测试
        快速点击多次http://localhost:8401/testA
        结果

        思考
          直接调用默认报错原因，技术方面OK，但是应该要有设置对应的报错信息和界面方便管理
    关联
      是什么
        当关联的资源达到阈值时，就限流自己
        当与A关联的资源B达到阈值后，就限流A自己
        B惹事，A挂了
      配置A

      postman模拟并发密集访问testB
        postman开启20个线程每隔0.3s请求/testB,导致A挂了
      运行后发现testA挂了
   
  流控效果
    直接-> 快速失败（默认的流控处理）
      直接失败，抛出异常
        Blocked by Sentinel(flowing limit)
    预热
      说明
        公式：阈值除以coldFactor(默认值为3)，经过预热时长后才会阈值
      官网
        默认ColdFactor为3，即请求QPS从threashold/3开始，经预热时长逐渐升到设定的QPS阈值
        限流冷启动
      WarmUp配置

      多次点击http://localhost:8401/testB
      应用场景

    排队等待
      匀速排队，严格控制请求通过的间隔时间

      官网

      测试
        postman设置请求发送速率即可 

降级规则

  基本介绍
    进一步说明
    Sentinel的断路器是没有半开状态的
      半开的状态，系统会自动检测是否请求有异常，没有异常就关闭断路器恢复使用，有异常则继续打开断路器不可用，具体可以参考Hystrix
    RT
      是什么

   

  测试
        代码

@GetMapping("/testD")
public String testD() {try {TimeUnit.SECONDS.sleep(1);} catch (InterruptedException e) {e.printStackTrace();}log.info("testD 测试RT");return "----testD";
}

        配置

        jmeter压测
        结论

    异常比例
      是什么

     

配置

      jmeter设置每秒10个请求即可
      结论

    异常数
      是什么

      异常数是按照分钟统计的
      测试
        代码

@GetMapping("/testE")
public String testE() {log.info("testE 测试异常数");int age = 10 / 0;return "----testE 测试异常数";
}

        配置

     

  jmeter 

热点key限流

  基本介绍
    是什么

 

    @SentinelResource

  代码

@GetMapping("/testHotKey")
@SentinelResource(value = "testHotKey",blockHandler = "deal_testHotKey")
public String testHotKey(@RequestParam(value = "p1",required = false)String p1,@RequestParam(value = "p2",required = false)String p2) {return "----testHotKey";
}public String deal_testHotKey(String p1, String p2, BlockException exception) {return "----deal_testHotKey, o(╥﹏╥)o"; // sentinel的默认提示都是： Blocked by Sentinel (flow limiting)
}

    com.alibaba.csp.sentinel.slots.block.BlockException
  配置

    1
      @SentinelResource(value = "testHotKey"）
      异常会直接打印到前台用户界面，提示不太友好
    2
      @SentinelResource(value = "testHotKey",blockHandler = "deal_testHotKey")
      方法testHotKey里面第一个参数只要QPS超过每秒1次，马上降级处理
      用了我们自己定义的

  参数例外项
    上诉案例演示了第一个参数p1,当QPS超过1秒1次点击后马上被限流
    特例情况
      普通
        超过1秒钟一个后，达到阈值1后马上被限流
      我们期望p1参数当它是某一个特殊值时，它的限流值和平时不一样
      特例
        假如当p1的值等于5时，它的QPS可以为200
    配置

    测试
      http://localhost:8401/testHotKey?p1=1&p2=2
      http://localhost:8401/testHotKey?p1=5&p2=2
      当p1为5的时候，阈值QPS变为了200
    前提条件
      热点参数的注意点，参数必须为基本类型或者String
  其他
    添加一个java运行异常试试 

系统规则

  是什么

 

@SentinelResource

配置@SentinelResource后如果想使用blockHandler配置流控规则的资源名就必须使用@SentinelResource的value值

  按资源名称限流+后续处理
    启动Nacos成功
    启动Sentinel成功
    Module
      cloudalibaba-sentinel-service8401
      业务类RateLimitController

 @GetMapping("/testHotKey")@SentinelResource(value = "testHotKey",blockHandler = "deal_testHotKey")public String testHotKey(@RequestParam(value = "p1",required = false)String p1,@RequestParam(value = "p2",required = false)String p2) {return "----testHotKey";}public String deal_testHotKey(String p1, String p2, BlockException exception) {return "----deal_testHotKey, o(╥﹏╥)o"; // sentinel的默认提示都是： Blocked by Sentinel (flow limiting)}

    配置流控规则

    
      一秒点击一次，ok，疯狂点击，返回自己定义的限流处理信息，限流发生
    额外问题
      此时关闭服务8401
      Sentinel控制台，流控规则消失了？？
        所以说规则是跟着微服务的生命周期的

  上面兜底方案面临的问题

  客户自定义限流处理逻辑
    创建CustomerBlockHandler类用于自定义限流处理逻辑
    自定义限流处理类
      CustomerBlockHandler

public class CustomerBlockHandler {public static String customBlockHandler(BlockException e){return "限流！！！！！";}
}

注意：customBlockHandler方法必须是静态的，否则无法被调用
    RateLimitController

 @GetMapping("/customBlockHandler")@SentinelResource(value="customBlockHandler",blockHandlerClass = CustomerBlockHandler.class,blockHandler = "customBlockHandler")public String customBlockHandler(){return "测试成功";}

    启动微服务后先调用一次
    Sentinel控制台配置

  
  更多注解属性说明

    多说一句

    Sentinel主要有三个核心API
      SPhU定义资源
      Tracer定义统计
      ContextUtil定义了上下文 

服务熔断功能

  Ribbon系列

    启动nacos和sentinel
    提供者9002/9001
      POM ，YML，主启动，没有变化
      业务类

@GetMapping("/getStr/{id}")public String getStr(@PathVariable("id")int id){return id+":"+serverPort;}

     
    消费者8401
        ApplicationContextConfig 

package com.hk.wms.wmscustom83.config;import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;@Configuration
public class ApplicationContextConfig {@Bean@LoadBalancedpublic RestTemplate getRestTemplate(){return  new RestTemplate();}
}

        CircleBreakerController

@GetMapping("/testF/{id}")@SentinelResource(value="testF",blockHandlerClass = CustomerBlockHandler.class,blockHandler = "customBlockHandler1",fallback = "handlerFallBack")public String CircleBreakerController(@PathVariable("id")int id){String str=template.getForObject(serverUrl+"/getStr/"+id,String.class);if(id<0){throw new IllegalArgumentException("IllegalArgument ,非法参数异常...");}if(str==null){throw new NullPointerException("NullPointerException,该ID没有对应记录，空指针异常");}return str;}

 

          修改后请重启微服务
            热部署对java代码级生效及时  ,对@SentinelResource注解内属性，有时效果不好
         
            fallback管运行异常,

 public String handlerFallBack(@PathVariable int id,Throwable e){return "异常";}

            blockHandler管配置违规

 public static String customBlockHandler1(@PathVariable int id, BlockException e){return "限流1！！！！！";}

注意：fallback方法和blockHandler方法必须有和@SentinelResource注解的方法具有同样的形参，否则无法生效

          同时配置fallback和blockHandler
          异常忽略
            
  Feign系列
    修改8401模块
      8401消费者调用提供者9002
      Feign组件一般是消费端
    POM

<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

    YML

server:port: 8401spring:application:name: wms-sentinal-servicecloud:nacos:discovery:#Nacos服务注册中心地址server-addr: 192.168.1.131:8848sentinel:transport:#配置Sentin dashboard地址dashboard: localhost:8080      #8080端口将会监控8401# 默认8719端口，假如被占用了会自动从8719端口+1进行扫描，直到找到未被占用的 端口port: 8719datasource:ds1:nacos:server-addr: 192.168.1.131:8848dataId: wms-sentinal-servicegroupId: DEFAULT_GROUPdata-type: jsonrule-type: flow
service-url:nacos-user-service: http://wms-provider
config-url:config-service: http://wms-config-3377management:endpoints:web:exposure:include: '*'
#激活sentinel对feign的支持
feign:sentinel:enabled: true

    业务类
      带@FeignClient注解的业务接口
      fallback = FeignFallbackService.class

package com.hk.wms.wmssentinelservice8401.service;import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;@FeignClient(value="wms-provider",fallback = FeignFallbackService.class)
public interface FeignService {@GetMapping(value="/getStr/{id}")public String getString(@PathVariable("id") int id);
}

用于处理服务方的异常错误 

package com.hk.wms.wmssentinelservice8401.service;import org.springframework.stereotype.Component;@Component
public class FeignFallbackService implements FeignService{@Overridepublic String getString(int id) {return "服务降级返回";}
}

      Controller

 @GetMapping("/testE/{id}")@SentinelResource(value="testE",blockHandlerClass = CustomerBlockHandler.class,blockHandler = "customBlockHandler2",fallback = "handlerFallBack")public String getStrController(@PathVariable("id")int id){String str=feignService.getString(id);if(id<0){throw new IllegalArgumentException("IllegalArgument ,非法参数异常...");}if(str==null){throw new NullPointerException("NullPointerException,该ID没有对应记录，空指针异常");}return str;}

fallback管运行异常,

 public String handlerFallBack(@PathVariable int id,Throwable e){return "异常";}

  blockHandler管配置违规

 public static String customBlockHandler2(@PathVariable int id, BlockException e){return id+"限流1！！！！！";}

注意：fallback方法和blockHandler方法必须有和@SentinelResource注解的方法具有同样的形参，否则无法生效

 

主启动
      添加@EnableFeignClients启动Feign的功能

package com.hk.wms.wmssentinelservice8401;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class WmsSentinelService8401Application {public static void main(String[] args) {SpringApplication.run(WmsSentinelService8401Application.class, args);}}

代码

package com.hk.wms.wmssentinelservice8401.controller;import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.hk.wms.wmssentinelservice8401.myhandler.CustomerBlockHandler;
import com.hk.wms.wmssentinelservice8401.service.FeignService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;import javax.annotation.Resource;@RestController
@Slf4j
public class FlowLimitController {@ResourceFeignService feignService;@Value("${service-url.nacos-user-service}")String serverUrl ;@Value("${config-url.config-service}")String configUrl;@AutowiredRestTemplate template;@GetMapping("/testA")@SentinelResource(value="testA",blockHandler = "deal_testA")public String testA(@RequestParam(value="p1",required = false)String p1) {System.out.println(Thread.currentThread().getName()+".................testA");return "----testA";}@GetMapping("/testB")@SentinelResource(value="testB")public String testB() {try {Thread.sleep(800L);} catch (InterruptedException e) {e.printStackTrace();}finally {return "----testA";}}@GetMapping("/testC")public String testC() {return template.getForObject(serverUrl+"/provider/",String.class);}@GetMapping("/testHotKey")@SentinelResource(value = "testHotKey",blockHandler = "deal_testHotKey")public String testHotKey(@RequestParam(value = "p1",required = false)String p1,@RequestParam(value = "p2",required = false)String p2) {return "----testHotKey";}@GetMapping("/customBlockHandler")@SentinelResource(value="customBlockHandler",blockHandlerClass = CustomerBlockHandler.class,blockHandler = "customBlockHandler")public String customBlockHandler(){return "测试成功";}public String deal_testHotKey(String p1, String p2, BlockException exception) {return "----deal_testHotKey, o(╥﹏╥)o"; // sentinel的默认提示都是： Blocked by Sentinel (flow limiting)}public String deal_testA(String p1,BlockException e){return "----testA+";}@GetMapping("/testE/{id}")@SentinelResource(value="testE",blockHandlerClass = CustomerBlockHandler.class,blockHandler = "customBlockHandler2",fallback = "handlerFallBack")public String getStrController(@PathVariable("id")int id){String str=feignService.getString(id);if(id<0){throw new IllegalArgumentException("IllegalArgument ,非法参数异常...");}if(str==null){throw new NullPointerException("NullPointerException,该ID没有对应记录，空指针异常");}return str;}@GetMapping("/testF/{id}")@SentinelResource(value="testF",blockHandlerClass = CustomerBlockHandler.class,blockHandler = "customBlockHandler1",fallback = "handlerFallBack")public String CircleBreakerController(@PathVariable("id")int id){String str=template.getForObject(serverUrl+"/getStr/"+id,String.class);if(id<0){throw new IllegalArgumentException("IllegalArgument ,非法参数异常...");}if(str==null){throw new NullPointerException("NullPointerException,该ID没有对应记录，空指针异常");}return str;}public String handlerFallBack(@PathVariable int id,Throwable e){return "异常";}}

 自定义 blockHandler管配置违规

package com.hk.wms.wmssentinelservice8401.myhandler;import com.alibaba.csp.sentinel.slots.block.BlockException;
import org.springframework.web.bind.annotation.PathVariable;/****/
public class CustomerBlockHandler {public static String customBlockHandler(BlockException e){return "限流！！！！！";}public static String customBlockHandler1(@PathVariable int id, BlockException e){return "限流1！！！！！";}public static String customBlockHandler2(@PathVariable int id, BlockException e){return id+"限流1！！！！！";}
}

 

 熔断框架比较

Sentinel规则持久化

    一旦我们重启应用，sentinel规则将消失，生产环境需要将配置规则进行持久化
  将限流配置规则持久化进Nacos保存，只要刷新8401某个rest地址，sentinel控制台的流控规则就能看到，只要Nacos里面的配置不删除，针对8401上sentinel上的流控规则持续有效
  步骤
    修改cloudalibaba-sentinel-service8401
    POM

 

 <dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency>

  YML

server:port: 8401spring:application:name: wms-sentinal-servicecloud:nacos:discovery:#Nacos服务注册中心地址server-addr: 192.168.1.131:8848sentinel:transport:#配置Sentin dashboard地址dashboard: localhost:8080      #8080端口将会监控8401# 默认8719端口，假如被占用了会自动从8719端口+1进行扫描，直到找到未被占用的 端口port: 8719
#datasource是sentinel的一个属性datasource:ds1:nacos:server-addr: 192.168.1.131:8848dataId: wms-sentinal-servicegroupId: DEFAULT_GROUPdata-type: jsonrule-type: flow
service-url:nacos-user-service: http://wms-provider
config-url:config-service: http://wms-config-3377
#暴露所有接口
management:endpoints:web:exposure:include: '*'
#激活sentinel对feign的支持
feign:sentinel:enabled: true

#datasource是sentinel的一个属性datasource:ds1:nacos:server-addr: 192.168.1.131:8848dataId: wms-sentinal-servicegroupId: DEFAULT_GROUPdata-type: jsonrule-type: flow

注意：datasource是sentinel的一个属性,properties写法：spring.cloud.sentinel.datasource

   

添加Nacos业务规则配置

[{"resource": "testF","limitApp": "default","grade": 1,"count": 1,"strategy": 0,"controlBehavior": 0,"clusterMode": false}
]

      内容解析

注意：resource的写法有两种，一种是按照路径的写法，就是@requestMapping的value，一种是写 @SentinelResource 的value   

  这一步的作用是每次消费者微服务启动时在nacos中定义sentinel的流控规则，从而做到持久化的效果
    启动8401后刷新sentinel发现业务规则有了
    停止8401再看sentinel
      发现流控规则没有了
    重新启动8401再看sentinel
      咋一看没有，但是你调用 /rateLimit/byUrl后它就会出现