SpringCloud11-Alibaba_Sentinel（熔断与限流）-CFANZ编程社区

1、Sentinel介绍

（1）Hystrix缺点：

需要手工搭建监控平台；
没有界面监控细粒度化的配置；
Sentinel是一个可以独立出来的单独组件，界面化统一配置；

（2）作用：

从流量监控、熔断降级、负载均衡保护等多个维度保护服务的稳定性；

（3）特性

丰富的应用场景：秒杀、削峰、熔断等多场景使用；
完备的实时监控：实时监控；
广泛的开源生态：开箱即用，快速整合；
完善的SPI扩展点：快速扩展定制逻辑；

2、下载安装

注意8080端口不要被占用

（1）下载：https://github.com/alibaba/Sentinel/releases
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（2）接下来步骤查看：https://blog.csdn.net/weixin_45176509/article/details/123583281

3、使用

pom.xml

       <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            <version>0.9.0.RELEASE</version>
        </dependency>

<?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>cloud2022</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.consumer8083</groupId>
    <artifactId>cloud-alibaba-consumer8083</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            <version>0.9.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
            <version>2.2.7.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>0.9.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.commons</groupId>
            <artifactId>commons</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>
        <!--mysql-connector-java-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--jdbc-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <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-autoconfigure</artifactId>
        </dependency>

    </dependencies>

</project>

application.yml

server:
  port: 8083

spring:
  application:
    name: consumer-nacos
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
      config:
        server-addr: localhost:8848
        file-extension: yaml
    sentinel: #配置
      transport:
        dashboard: localhost:8080
        port: 8719 #默认为8719，如果占用会从8719+1开始扫描寻找未占用端口

management: #暴露监控
  endpoints:
    web:
      exposure.include: '*'

在这里插入图片描述

主启动

package com.consumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class NacosConsumerDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(NacosConsumerDemoApplication.class, args);
    }


}

业务Controller：未作变化，与Nacos相同

package com.consumer.Controller;

import com.commons.Entity.Result;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;

@RestController
@RequestMapping("nacos/")
@RefreshScope //动态刷新
public class ConsumerController {

    @Resource
    private RestTemplate restTemplate;

    @Value("${spring.datasource.username}")
    private String configInfo;

    @Value("${service-url.nacos-user-service}")
    private String url;

    @GetMapping("/{id}")
    public Result saveEntity(@PathVariable("id") Integer id) {

        return restTemplate.getForObject(url+"/nacos/"+id,Result.class);
    }

    @GetMapping("/getInfo")
    public String getInfo() {
        return configInfo;
    }

}

启动项目，首次访问sentinel空空如也，他是懒加载机制，要访问接口之后才会加载，访问Controller接口，再次访问，效果如下：

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4、规则

（1）簇点链路

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（2）流控规则

配置说明：
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阈值类型
配置QPS快速失败：

QPS：御敌于国门之外；
线程数：关门打狗；
流控模式

直接：默认模式；

关联：当与自己关联的资源达到阈值后就限流自己；
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链路：多个请求操作同一个微服务

流控效果

快速失败：默认处理;

WarmUp（预热）：长期处于低访问，在某一时刻高访问，需要通过限流慢慢启动，预热时长之后才会慢慢达到单价阈值；
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排队等待：排队挨个挨个处理
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（3）熔断降级

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Sentinel断路器非开即断，没有半开状态；

RT(平均响应时间)：当1秒内进入5个请求，平均响应时间均超过阈值，那么接下来的时间窗口之内，调用这个方法就会自动熔断，时间窗口期结束，关闭熔断。默认为4900ms，若要设置上线需要配置；
异常比例：当统计时间内，请求次数达到设置数，异常次数达到异常数，则发生熔断，超过熔断时长，关闭熔断；
异常数：当统计时间内，请求次数达到设置数，异常比列到达设置比例，则发生熔断，超过熔断时长，关闭熔断；

（4）热点Key规则

热点即为经常访问的数据；
访问时根据路径是否携带约定参数来决定是否需要限流；

实现：

配置：当第一个参数存在，并且1秒内访问超过1次，就使用配置方法。

在这里插入图片描述

接口： @SentinelResource(value = "nacosId",blockHandler = "dealHandler")

该注解执行的是配置的热点规则，如果出现java异常，不会执行限流方法；

package com.consumer.Controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.commons.Entity.Result;
import com.sun.deploy.security.BlockedException;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;

@RestController
@RequestMapping("nacos/")
@RefreshScope //动态刷新
public class ConsumerController {

    @Resource
    private RestTemplate restTemplate;

    @Value("${spring.datasource.username}")
    private String configInfo;

    @Value("${service-url.nacos-user-service}")
    private String url;

    @GetMapping("/{id}")
    @SentinelResource(value = "nacosId",blockHandler = "dealHandler")
    public Result saveEntity(@PathVariable("id") Integer id,
                             @RequestParam(value = "p1",required = false) String p1,
                             @RequestParam(value = "p2",required = false) String p2) {

        return restTemplate.getForObject(url+"/nacos/"+id,Result.class);
    }

    public Result dealHandler(Integer id, String p1, String p2, BlockException blockException){
        Result result = new Result(404,"/","");
        return result;
    }

}

踩坑：com.alibaba.csp.sentinel.slots.block.flow.FlowException

是否与原方法参数一致；
是否与原方法返回值一致；
是否添加BlockException参数；

参数例外项

以上例子指定某个位置参数后，就会对该参数进行统计限流，但是有时候希望该参数携带某个特殊值时，对它进行特殊限流规则；
当第一个参数值为5时，阈值可达100才会限流；

（5）系统自适应规则

从整体维度应用入口进行控制，该规则会对整个服务应用起作用；

维度	描述
Load自适应	系统最高负载，建议取值 CPU cores * 2.5
并发线程数	单机应用的最大线程并发数
入口QPS	单机应用维度入口QPS
平均RT	单机应用所有请求的平均RT
CPU使用率	CPU使用率，取值范围[0, 1]

5、配置使用

5.1 @SentinelResource配置

不支持private方法；

@RestController
public class RateLimitController {

    @GetMapping("/getRate")
    @SentinelResource(value = "getRate" ,blockHandler = "error")
    public Result get(){
        return new Result(200,"正常访问","200");
    }

    public Result error(BlockException blockException){
        return new Result(404,blockException.getClass().getName()+"异常访问","404");
    }
}

存在2种配置：

使用限流资源名称配置：getRate
使用访问Url配置：/getRate

如果有配置blockHandler 方法，则使用该方法，没有则使用系统默认方法；

以上配置导致业务代码和处理代码混合，每个方法都需要配置，导致代码膨胀，改造如下:

提出单独的Handler处理规则，注意方法参数值和返回类型要一致

package com.consumer.Handler;

import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.commons.Entity.Result;

public class BlockHandler {
    public static Result error1(BlockException blockException){
        return new Result(404,blockException.getClass().getName()+"异常访问1","404");
    }

    public static Result error2(BlockException blockException){
        return new Result(404,blockException.getClass().getName()+"异常访问2","404");
    }
}

更改注解配置： @SentinelResource(value = "getRate" ,blockHandlerClass = BlockException.class,blockHandler = "error1")

package com.consumer.Controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.commons.Entity.Result;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class RateLimitController {

    @GetMapping("/getRate")
    @SentinelResource(value = "getRate" ,blockHandlerClass = BlockException.class,blockHandler = "error1")
    public Result get(){
        return new Result(200,"正常访问","200");
    }
    
}

在这里插入图片描述
Sentinel核心API：Sphu（定义资源）、Tracer（定义统计）、ContextUtil（定义上下文）

6、整合

6.1 Ribbon搭建

pom.xml

 <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            <version>0.9.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
            <version>2.2.7.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>0.9.0.RELEASE</version>
        </dependency>

application.yml

spring:
  application:
    name: consumer-nacos
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
      config:
        server-addr: localhost:8848
        file-extension: yaml
    sentinel: #配置******************************
      transport:
        dashboard: localhost:8080
        port: 8719 #默认为8719，如果占用会从8719+1开始扫描寻找未占用端口

management: #暴露监控
  endpoints:
    web:
      exposure.include: '*'

主启动

package com.consumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class NacosConsumerDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(NacosConsumerDemoApplication.class, args);
    }

}

业务Controller

package com.consumer.Controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.commons.Entity.Result;
import com.sun.deploy.security.BlockedException;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;

@RestController
@RequestMapping("nacos/")
@RefreshScope //动态刷新
public class ConsumerController {

    @Resource
    private RestTemplate restTemplate;

    @Value("${spring.datasource.username}")
    private String configInfo;

    @Value("${service-url.nacos-user-service}")
    private String url;

    @GetMapping("/{id}")
    @SentinelResource(value = "nacosId")
    public Result saveEntity(@PathVariable("id") Integer id,
                             @RequestParam(value = "p1",required = false) String p1,
                             @RequestParam(value = "p2",required = false) String p2) {

        return restTemplate.getForObject(url+"/nacos/"+id,Result.class);
    }

}

RestTemplate配置

package com.consumer.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 RestTemplateConfig {

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

在这里插入图片描述

6.2 fallback处理运行时异常，blockHandler处理配置违规

只改造业务Controller，其他相同

package com.consumer.Controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.commons.Entity.Result;
import com.sun.deploy.security.BlockedException;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;

@RestController
@RequestMapping("nacos/")
@RefreshScope //动态刷新
public class ConsumerController {

    @Resource
    private RestTemplate restTemplate;

    @Value("${spring.datasource.username}")
    private String configInfo;

    @Value("${service-url.nacos-user-service}")
    private String url;

    @GetMapping("/{id}")
    //fallback处理运行时异常，blockHandler处理配置违规
    @SentinelResource(value = "nacosId",fallback = "dealHandler1" ,blockHandler = "dealHandler2")
    public Result saveEntity(@PathVariable("id") Integer id,
                             @RequestParam(value = "p1",required = false) String p1,
                             @RequestParam(value = "p2",required = false) String p2) {

        return restTemplate.getForObject(url+"/nacos/"+id,Result.class);
    }

    public Result dealHandler1(Integer id, String p1, String p2, BlockException blockException){
        Result result = new Result(404,"/","1");
        return result;
    }

    public Result dealHandler2(Integer id, String p1, String p2, BlockException blockException){
        Result result = new Result(404,"/","2");
        return result;
    }
}

当二者同时出现方法调用时，blockHandler 优先级高于fallback ；

异常忽略 exceptionsToIgnore

  @GetMapping("/{id}")
    @SentinelResource(value = "nacosId",fallback = "dealHandler1" ,blockHandler = "dealHandler2",
    exceptionsToIgnore = {IllegalArgumentException.class})
    public Result saveEntity(@PathVariable("id") Integer id,
                             @RequestParam(value = "p1",required = false) String p1,
                             @RequestParam(value = "p2",required = false) String p2) {

        return restTemplate.getForObject(url+"/nacos/"+id,Result.class);
    }

配置该属性之后，如果发生IllegalArgumentException异常不会执行fallback 指定方法；

断路方式对比

Sentinel	Hystrix
信号量隔离	线程池、信号量隔离
基于响应时间、异常比率、异常数	基于异常比率
基于QPS、调用关系限流	有限的限流支持

7 、规则持久化

重启服务，配置的规则回消失，需要将规则持久化保存；
可以通过eureka、nacos、consul、redis等持久化媒介实现，官方推荐nacos。

7.1 实现

pom.xml

        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-datasource-nacos</artifactId>
        </dependency>

<?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>cloud2022</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.consumer8083</groupId>
    <artifactId>cloud-alibaba-consumer8083</artifactId>

    <dependencies>
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-datasource-nacos</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            <version>0.9.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
            <version>2.2.7.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>0.9.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.commons</groupId>
            <artifactId>commons</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>
        <!--mysql-connector-java-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--jdbc-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <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-autoconfigure</artifactId>
        </dependency>

    </dependencies>

</project>

application.yml

   #数据数据源
      datasource: 
        ds1: #数据源1
          nacos:
            server-addr: localhost:8848 #nacos地址
            dataId: cloudalibaba-sentinel-service  #dataId名称
            groupId: DEFAULT_GROUP #分组名称
            data-type: json #文件类型
            rule-type: flow

server:
  port: 8083

spring:
  application:
    name: consumer-nacos
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
      config:
        server-addr: localhost:8848
        file-extension: yaml
    sentinel: #配置
      transport:
        dashboard: localhost:8080
        port: 8719 #默认为8719，如果占用会从8719+1开始扫描寻找未占用端口
        #数据数据源
      datasource:
        ds1: #数据源1
          nacos:
            server-addr: localhost:8848 #nacos地址
            dataId: cloudalibaba-sentinel-service  #dataId名称
            groupId: DEFAULT_GROUP #分组名称
            data-type: json #文件类型
            rule-type: flow

management: #暴露监控
  endpoints:
    web:
      exposure.include: '*'

 #激活feign对sentinel支持
feign:
  sentinel:
    enabled: true

主启动

package com.consumer;

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 NacosConsumerDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(NacosConsumerDemoApplication.class, args);
    }


}

Nacos设置规则

在这里插入图片描述

    resourcenacosId：资源名称
    limitAppdefalut： 来源应用
    grade：阈值类型：0-线程数 1-QPS
    count：单机阈值
    strategy： 流控模式 0-直接 1-关联 2-链路
    controlBehavior：流控效果：0-快速失败 2-WarmUp 3-表示排队等待
    clusterModefalse ：是否集群

Sentinel流控规则
需要调用接口触发，否则此处为空；

总结