sentinel 热点限流

官网：https://sentinelguard.io/zh-cn/docs/parameter-flow-control.html

热点限流

sentinel使用lru算法统计最近最常使用的热点参数，结合令牌桶算法进行限流

# 热点数据限流：统计热点参数，根据配置的限流阈值与模式，对包含热点参数的资源进行限流
参数为商品id，统计一段时间内最常购买的商品ID并进行限制
参数为用户id，针对一段时间内频繁访问的用户ID进行限制

***********

基本使用

相关依赖

        <!-- spring-cloud-alibaba-starter-sentinel中有该依赖 --><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-parameter-flow-control</artifactId><version>x.y.z</version></dependency>

ParamFlowRule

public class ParamFlowRule extends AbstractRule {private int grade = 1;              //限流模式：QPS（默认）、并发线程数private Integer paramIdx;           //热点参数索引private double count;               //限流阈值private int controlBehavior = 0;    //流控行为：快速失败（默认）、匀速排队模式private int maxQueueingTimeMs = 0;  //匀速排队模式时排队等待时间private int burstCount = 0;         //处理突发流量private long durationInSec = 1L;    //限流窗口时长，默认1sprivate List<ParamFlowItem> paramFlowItemList = new ArrayList();//针对指定的参数值单独设置限流阈值，不受count影响//仅支持基本类型和字符串类型private Map<Object, Integer> hotItems = new HashMap();private boolean clusterMode = false;  //是否为集群模式，集群模式传入的参数只支持基本类型和字符串类型private ParamFlowClusterConfig clusterConfig;  //集群限流配置public ParamFlowRule() {}public ParamFlowRule(String resourceName) {this.setResource(resourceName);}

AbstractRule

public abstract class AbstractRule implements Rule {private String resource;    //需要限流的资源名称private String limitApp;    //特定资源、default（不限资源）、otherpublic AbstractRule() {}

ParamFlowClusterConfig

public class ParamFlowClusterConfig {private Long flowId;                    //热点参数集群流控id，需保证全局唯一private int thresholdType = 0;          //阀值模式：0（单机均摊）、1（全局模式）private boolean fallbackToLocalWhenFail = false;  //client连接失败或通信失败时，是否退化到本地的限流模式private int sampleCount = 10;           //窗口数量private int windowIntervalMs = 1000;    //窗口统计时长，默认1spublic ParamFlowClusterConfig() {}

设置热点参数规则

    private static void initParamFlowRules() {// QPS mode, threshold is 5 for every frequent "hot spot" parameter in index 0 (the first arg).ParamFlowRule rule = new ParamFlowRule(RESOURCE_KEY).setParamIdx(0).setGrade(RuleConstant.FLOW_GRADE_QPS)//.setDurationInSec(3)//.setControlBehavior(RuleConstant.CONTROL_BEHAVIOR_RATE_LIMITER)//.setMaxQueueingTimeMs(600).setCount(5);// We can set threshold count for specific parameter value individually.// Here we add an exception item. That means: QPS threshold of entries with parameter `PARAM_B` (type: int)// in index 0 will be 10, rather than the global threshold (5).ParamFlowItem item = new ParamFlowItem().setObject(String.valueOf(PARAM_B)).setClassType(int.class.getName()).setCount(10);rule.setParamFlowItemList(Collections.singletonList(item));ParamFlowRuleManager.loadRules(Collections.singletonList(rule));}

使用示例

***********

相关依赖

        <!-- 服务注册与发现 --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!-- 服务调用 --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-dubbo</artifactId></dependency><!-- sentinel dubbo适配器 --><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-apache-dubbo-adapter</artifactId><version>1.8.0</version></dependency><!-- dubbo应用向控制台传输数据 --><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-transport-simple-http</artifactId><version>1.8.0</version></dependency><!-- 热点限流 --><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-parameter-flow-control</artifactId><version>1.8.0</version></dependency>

***********

服务端

application.yml

spring:application:name: nacos-providercloud:nacos:discovery:server-addr: localhost:8848dubbo:protocol:name: dubboport: -1

HelloService

public interface HelloService {String hello(String name);
}

HelloServiceImpl

@DubboService
public class HelloServiceImpl implements HelloService {@Overridepublic String hello(String name) {return "hello " + name;}
}

DemoApplication

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

***********

消费端

application.yml

spring:application:name: nacos-consuemrcloud:nacos:discovery:server-addr: localhost:8848dubbo:protocol:name: dubboport: -1server:port: 8081

HelloService

public interface HelloService {String hello(String name);
}

HelloController

@RestController
public class HelloController {@DubboReferenceprivate HelloService helloService;@RequestMapping("/hello")public String hello(){System.out.println(helloService.hello("瓜田李下"));return "success";}
}

***********

本地限流配置

CustomParamFlowRule

public class CustomParamFlowRule implements InitFunc {@Overridepublic void init() throws Exception {ParamFlowRule paramFlowRule = new ParamFlowRule("com.example.demo.service.HelloService:hello(java.lang.String)");paramFlowRule.setParamIdx(0).setGrade(RuleConstant.FLOW_GRADE_QPS).setCount(2);ParamFlowItem paramFlowItem = new ParamFlowItem();paramFlowItem.setObject("瓜田李下")    //name=瓜田李下的限流阀值是4//name为其他值的限流阀值是2.setClassType(String.class.getName()).setCount(4);paramFlowRule.setParamFlowItemList(Collections.singletonList(paramFlowItem));ParamFlowRuleManager.loadRules(Collections.singletonList(paramFlowRule));}
}

META-INF/services/com.alibaba.csp.sentinel.init.InitFunc

com.example.demo.config.CustomParamFlowRule

jmeter测试

***********

控制台限流配置

控制台启动

java -Dserver.port=8000 -Dcsp.sentinel.dashboard.server=localhost:8000 -Dproject.name=sentinel-dashboard -jar sentinel-dashboard.jar参数说明：
-Dserver.port=8080：指定控制台启动端口
-Dcsp.sentinel.dashboard.server：指定控制台地址和端口
-Dproject.name=sentinel-dashboard：指定控制台项目名称

服务端启动

-Dserver.port=8080 -Dcsp.sentinel.dashboard.server=localhost:8000 -Dproject.name=nacos-provider

消费端启动

-Dserver.port=8081 -Dcsp.sentinel.dashboard.server=localhost:8000 -Dproject.name=nacos-consumer

sentinel 控制台：localhost:8000

jmeter 测试