Sentinel实现熔断与限流

1.sentinel官网

1.2官网

https://github.com/alibaba/Sentinel
https://github.com/alibaba/Sentinel/wiki/%E4%BB%8B%E7%BB%8D
下载源码地址

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1.2主要特性

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1.3使用场景

https://spring-cloud-alibaba-group.github.io/github-pages/greenwich/spring-cloud-alibaba.html#_spring_cloud_alibaba_sentinel
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

2.安装Sentinel控制台

2.1sentinel组件由2部分组成

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2.2运行环境

下载https://github.com/alibaba/Sentinel/releases （1.8v）
sentinel-dashboard-1.8.0.jar
java8环境；
8080端口不能被占用(linux下开启防火墙端口)
命令：java -jar sentinel-dashboard-1.8.0.jar

2.3访问sentinel管理界面：

http://localhost:8080（登录账号密码均为sentinel）

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3.初始化演示工程

启动Nacos8848成功

3.1创建module

cloudalibaba-sentinel-service8401

3.2POM依赖

        
            com.atguigu.springcloud
            cloud-api-commons
            ${project.version}
        

        
            com.alibaba.cloud
            spring-cloud-starter-alibaba-nacos-discovery
        

        
            com.alibaba.csp
            sentinel-datasource-nacos
        

        
            com.alibaba.cloud
            spring-cloud-starter-alibaba-sentinel
        

        
            org.springframework.cloud
            spring-cloud-starter-openfeign
        

        
            org.springframework.boot
            spring-boot-starter-web
        
        
            org.springframework.boot
            spring-boot-starter-actuator
        
      
        
            org.springframework.boot
            spring-boot-devtools
            runtime
            true
        
        
            cn.hutool
            hutool-all
            4.6.3
        
        
            org.projectlombok
            lombok
            true
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
    

3.3YML配置

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-sentinel-service
  cloud:
    nacos:
      discovery:
        server-addr: 192.168.1.111:1111
    sentinel:
      transport:
        dashboard: 192.168.1.111:8080
        port: 8719  #默认8719，假如被占用了会自动从8719开始依次+1扫描。直至找到未被占用的端口

management:
  endpoints:
    web:
      exposure:
        include: '*'

3.4启动类

@EnableDiscoveryClient  //nacos
@SpringBootApplication
public class MainApp8401
{
    public static void main(String[] args) {
        SpringApplication.run(MainApp8401.class, args);
    }
}

3.5业务类FlowLimitController

@RestController
public class FlowLimitController
{
    @GetMapping("/testA")
    public String testA() {
        return "------testA";
    }
    @GetMapping("/testB")
    public String testB() {

        return "------testB";
    }
}

启动Sentinel8080：java -jar sentinel-dashboard-1.8.0
启动微服务8401
启动8401微服务后查看sentienl控制台
Sentinel采用的懒加载说明:需要执行一次调用http://localhost:8401/testA
sentinel8080正在监控微服务8401

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4.流控规则

4.1新增

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4.2流控模式

4.2.1系统默认

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4.2.2测试
快速点击访问http://localhost:8401/testA

Blocked by Sentinel (flow limiting)直接调用默认报错信息(后续fallback的兜底方法)

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4.3关联

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，就限流自己
B惹事，A挂了

4.3.1配置

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4.3.2测试
postman模拟并发密集访问testB
大批量线程高并发访问B，导致A失效了

4.4链路

多个请求调用了同一个微服务

4.4.1流控效果
默认直接失败，抛出异常（Blocked by Sentinel (flow limiting)）
com.alibaba.csp.sentinel.slots.block.flow.controller.DefaultController
预热
公式：阈值除以coldFactor（默认值为3），经过预热时长后才会达到阈值

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https://github.com/alibaba/Sentinel/wiki/%E9%99%90%E6%B5%81---%E5%86%B7%E5%90%AF%E5%8A%A8

4.4.2源码
com.alibaba.csp.sentinel.slots.block.flow.controller.WarmUpController

4.4.3Warmup配置

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多次点击http://localhost:8401/testB，刚开始不行，后续慢慢OK

4.4.4排队等待

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匀速排队，阈值必须设置为QPS

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com.alibaba.csp.sentinel.slots.block.flow.controller.RateLimiterController

5.降级规则

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Sentinel的断路器是没有半开状态的
半开的状态系统自动去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

5.1降级策略实战RT

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5.1.1测试

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

5.1.2配置

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5.2异常比例

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5.2.1测试代码

@GetMapping("/testD")
    public String testD()
    {
        log.info("testD 测试RT");
        int age = 10/0;
        return "------testD";
    }

5.2.2配置

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5.2.3结果

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5.3异常数

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异常数是按照分钟统计的

5.3.1测试

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

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5.4热点key限流

官网：https://github.com/alibaba/Sentinel/wiki/热点参数限流
@SentinelResource
com.alibaba.csp.sentinel.slots.block.BlockException
5.4.1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) {
    //int age = 10/0;
    return "------testHotKey";
}
 
//兜底方法
public String deal_testHotKey (String p1, String p2, BlockException exception){
    return "------deal_testHotKey,o(╥﹏╥)o";  
}

5.4.2配置

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1.@SentinelResource(value = "testHotKey")
异常打到了前台用户界面看不到，不友好

2.@SentinelResource(value = "testHotKey",blockHandler = "deal_testHotKey")
方法testHostKey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

error
http://localhost:8401/testHotKey?p1=abc
http://localhost:8401/testHotKey?p1=abc&p2=33
right
http://localhost:8401/testHotKey?p2=abc

5.5参数例外项

上述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
特殊情况
我们期望p1参数当它是某个特殊值时，它的限流值和平时不一样
假如当p1的值等于5时，它的阈值可以达到200

5.5.1配置

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5.5.2测试
http://localhost:8401/testHotKey?p1=5当p1等于5的时候，阈值变为200
http://localhost:8401/testHotKey?p1=3当p1不等于5的时候，阈值就是平常的1

6系统规则

https://github.com/alibaba/Sentinel/wiki/%E7%B3%BB%E7%BB%9F%E8%87%AA%E9%80%82%E5%BA%94%E9%99%90%E6%B5%81

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6.1配置全局QPS

@SentinelResource
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

6.1.1POM

    com.atguigu.springcloud
    cloud-api-commons
    ${project.version}

6.1.2YML

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-sentinel-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    sentinel:
      transport:
        dashboard: localhost:8080
        port: 8719  #默认8719，假如被占用了会自动从8719开始依次+1扫描。直至找到未被占用的端口

management:
  endpoints:
    web:
      exposure:
        include: '*'

6.1.3业务类RateLimitController

@RestController
public class RateLimitController
{
    @GetMapping("/byResource")
    @SentinelResource(value = "byResource",blockHandler = "handleException")
    public CommonResult byResource()
    {
        return new CommonResult(200,"按资源名称限流测试OK",new Payment(2020L,"serial001"));
    }
    public CommonResult handleException(BlockException exception)
    {
        return new CommonResult(444,exception.getClass().getCanonicalName()+"\t 服务不可用");
    }

主启动后

@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401
{
    public static void main(String[] args) {
        SpringApplication.run(MainApp8401.class, args);
    }

}

6.2配置流控规则

6.2.1配置步骤

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图形配置和代码关系
表示1秒钟内查询次数大于1，就跑到我们自定义的处流，限流

6.2.2测试
1秒钟点击1下，OK
超过上述问题，疯狂点击，返回了自己定义的限流处理信息，限流发送

按照Url地址限流+后续处理
通过访问的URL来限流，会返回Sentinel自带默认的限流处理信息

@GetMapping("/rateLimit/byUrl")
@SentinelResource(value = "byUrl")
public CommonResult byUrl()
{
    return new CommonResult(200,"按url限流测试OK",new Payment(2020L,"serial002"));
}
 

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疯狂点击http://localhost:8401/rateLimit/byUrl
会返回sentinel自带的限流处理结果

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上面兜底方法面临的问题

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6.3客户自定义限流处理逻辑

6.3.1创建customerBlockHandler类用于自定义限流处理逻辑

public class CustomerBlockHandler {
    public static CommonResult handleException(BlockException exception) {
        return new CommonResult(2020, "自定义限流处理信息....CustomerBlockHandler");
    }
}

6.3.2RateLimitController

@GetMapping("/rateLimit/customerBlockHandler")
@SentinelResource(value = "customerBlockHandler",
        blockHandlerClass = CustomerBlockHandler.class,
        blockHandler = "handlerException2")
public CommonResult customerBlockHandler()
{
    return new CommonResult(200,"按客戶自定义",new Payment(2020L,"serial003"));
}

6.3.3启动微服务后先调用一次
http://localhost:8401/rateLimit/customerBlockHandler
6.3.4配置

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7.服务熔断功能

7.1概述

sentinel整合ribbon+openFeign+fallback

7.2Ribbon系列

新建消费者cloudalibaba-provider-payment9003/9004

7.2.1POM

    
    
        com.alibaba.cloud
        spring-cloud-starter-alibaba-nacos-discovery
    
    
        com.atguigu.springcloud
        cloud-api-commons
        ${project.version}
    
    
    
        org.springframework.boot
        spring-boot-starter-web
    
    
        org.springframework.boot
        spring-boot-starter-actuator
    
    
    
        org.springframework.boot
        spring-boot-devtools
        runtime
        true
    
    
        org.projectlombok
        lombok
        true
    
    
        org.springframework.boot
        spring-boot-starter-test
        test
    

7.2.2YML

server:
  port: 9003

spring:
  application:
    name: nacos-payment-provider
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848 #配置Nacos地址

management:
  endpoints:
    web:
      exposure:
        include: '*'

7.2.3启动类

@SpringBootApplication
@EnableDiscoveryClient
public class PaymentMain9003
{
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain9003.class, args);
    }
}

7.2.4业务类

@RestController
public class PaymentController
{
    @Value("${server.port}")
    private String serverPort;

    public static HashMap hashMap = new HashMap<>();
    static{
        hashMap.put(1L,new Payment(1L,"28a8c1e3bc2742d8848569891fb42181"));
        hashMap.put(2L,new Payment(2L,"bba8c1e3bc2742d8848569891ac32182"));
        hashMap.put(3L,new Payment(3L,"6ua8c1e3bc2742d8848569891xt92183"));
    }

    @GetMapping(value = "/paymentSQL/{id}")
    public CommonResult paymentSQL(@PathVariable("id") Long id){
        Payment payment = hashMap.get(id);
        CommonResult result = new CommonResult(200,"from mysql,serverPort:  "+serverPort,payment);
        return result;
    }
}

7.2.5新建消费者84
cloudalibaba-consumer-nacos-order84
7.2.6POM

    
        cloud2020
        com.atguigu.springcloud
        1.0-SNAPSHOT
    
    4.0.0

    cloudalibaba-consumer-nacos-order84

    
        
            org.springframework.cloud
            spring-cloud-starter-openfeign
        
        
            com.alibaba.cloud
            spring-cloud-starter-alibaba-nacos-discovery
        
        
            com.alibaba.cloud
            spring-cloud-starter-alibaba-sentinel
        
        
            com.atguigu.springcloud
            cloud-api-commons
            ${project.version}
        
        
            org.springframework.boot
            spring-boot-starter-web
        
        
            org.springframework.boot
            spring-boot-starter-actuator
        
        
            org.springframework.boot
            spring-boot-devtools
            runtime
            true
        
        
            org.projectlombok
            lombok
            true
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
    

7.2.6YML

server:
  port: 84

spring:
  application:
    name: nacos-order-consumer
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    sentinel:
      transport:
        dashboard: localhost:8080
        port: 8719

service-url:
  nacos-user-service: http://nacos-payment-provider

7.2.7主启动类

@EnableDiscoveryClient
@SpringBootApplication
@EnableFeignClients
public class OrderNacosMain84
{
    public static void main(String[] args) {
        SpringApplication.run(OrderNacosMain84.class, args);
    }
}

7.2.8业务类
ApplicationContextConfig

@Configuration
public class ApplicationContextConfig
{
    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate()
    {
        return new RestTemplate();
    }
}

CircleBreakerController的全部源码

@RestController
@Slf4j
public class CircleBreakerController {
    public static final String SERVICE_URL = "http://nacos-payment-provider";
    @Resource
    private RestTemplate restTemplate;
    @RequestMapping("/consumer/fallback/{id}")
    //@SentinelResource(value = "fallback") //没有配置
    //@SentinelResource(value = "fallback",fallback = "handlerFallback") //fallback只负责业务异常
    //@SentinelResource(value = "fallback",blockHandler = "blockHandler") //blockHandler只负责sentinel控制台配置违规
    @SentinelResource(value = "fallback",fallback = "handlerFallback",blockHandler = "blockHandler",
            exceptionsToIgnore = {IllegalArgumentException.class})
    public CommonResult fallback(@PathVariable Long id) {
        CommonResult result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id, CommonResult.class,id);

        if (id == 4) {
            throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常....");
        }else if (result.getData() == null) {
            throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常");
        }

        return result;
    }
  
    //fallback
    public CommonResult handlerFallback(@PathVariable  Long id,Throwable e) {
        Payment payment = new Payment(id,"null");
        return new CommonResult<>(444,"兜底异常handlerFallback,exception内容  "+e.getMessage(),payment);
    }
  
    //blockHandler
    public CommonResult blockHandler(@PathVariable  Long id,BlockException blockException) {
        Payment payment = new Payment(id,"null");
        return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException  "+blockException.getMessage(),payment);
    }
}

fallback管运行异常
blockHandler管配置违规

7.2.8测试地址
http://localhost:84/consumer/fallback/1给客户error页面，不友好

fallback和blockHandler都配置

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7.3Feign系列

7.3.1POM

    org.springframework.cloud
    spring-cloud-starter-openfeign

7.3.2YML

server:
  port: 84

spring:
  application:
    name: nacos-order-consumer
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    sentinel:
      transport:
        dashboard: localhost:8080
        port: 8719

service-url:
  nacos-user-service: http://nacos-payment-provider

#对Feign的支持
feign:
  sentinel:
    enabled: true

7.3.3业务类
带@FeignClient注解的业务接口

@FeignClient(value = "nacos-payment-provider",fallback = PaymentFallbackService.class)
public interface PaymentService
{
    @GetMapping(value = "/paymentSQL/{id}")
    public CommonResult paymentSQL(@PathVariable("id") Long id);
}

fallback = PaymentFallbackService.class
PaymentFallbackService实现类

@Component
public class PaymentFallbackService implements PaymentService
{
    @Override
    public CommonResult paymentSQL(Long id)
    {
        return new CommonResult<>(44444,"服务降级返回,---PaymentFallbackService",new Payment(id,"errorSerial"));
    }
}

controller

// OpenFeign
@Resource
private PaymentService paymentService;

@GetMapping(value = "/consumer/paymentSQL/{id}")
public CommonResult paymentSQL(@PathVariable("id") Long id) {
    return paymentService.paymentSQL(id);
}

添加@EnableFeignClients启动Feign的功能

@EnableDiscoveryClient
@SpringBootApplication
@EnableFeignClients
public class OrderNacosMain84
{
    public static void main(String[] args) {
        SpringApplication.run(OrderNacosMain84.class, args);
    }
}

http://lcoalhost:84/consumer/paymentSQL/1
测试84调用9003，此时故意关闭9003微服务提供者，看84消费侧自动降级，不会被耗死

7.4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

7.4.1步骤
修改cloudalibaba-sentinel-service8401
POM

    com.alibaba.csp
    sentinel-datasource-nacos

YML

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-sentinel-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848 #Nacos服务注册中心地址
    sentinel:
      transport:
        dashboard: localhost:8080 #配置Sentinel dashboard地址
        port: 8719
      datasource:  #添加Nacos数据源配置
        ds1:
          nacos:
            server-addr: localhost:8848
            dataId: cloudalibaba-sentinel-service
            groupId: DEFAULT_GROUP
            data-type: json
            rule-type: flow

management:
  endpoints:
    web:
      exposure:
        include: '*'

feign:
  sentinel:
    enabled: true # 激活Sentinel对Feign的支持

7.4.2添加Nacos业务规则配置

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7.4.3启动8401后刷新sentinel发现业务规则有了

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