Spring Alibaba Sentinel实现集群限流demo

1.背景

1.什么是单机限流？

小伙伴们或许遇到过下图这样的限流配置

又或者是这样的Nacos动态配置限流规则：

以上这些是什么限流？没错，就是单机限流，那么单机限流有什么弊端呢？

假设我们集群部署3台机器（NodeA/NodeB/NodeC），在某时刻，同时有25个请求进来，假设NodeA收到12个请求，NodeB 8个，NodeC 5个，并且每个单机限流qps=10，那么这个时候，NodeA将会触发限流，有两个请求BLOCK掉，这是由于可能发生的流量不均导致NodeA节点流量过高导致限流，这是因为每个机器都是自己管自己，有没有一种方法能够统筹调度呢？这就得提到集群限流了

2.什么是集群限流

集群限流就是，弄一台Token Server，每个客户端机器作为Token Client，有请求进来，Token Client就会向Token Server拿令牌，拿到令牌则不限流，反正则限流。其中Token Server可以作为独立运行的项目，也可以内嵌式内嵌至每个节点中（需将其中一台机器设置为Token Server，如果Token Server节点所在机器宕机，可以将其他Client节点设置成server，sentinel有相关api提供该操作）

例如上面的例子，集群内有3个节点，如果每个节点能承受10的请求，那么加起来就是3x10=30个请求。也就是说只要qps不超过30个请求都不会触发限流。

2.sentinel实现集群限流

1. 以spring-boot项目构建 sentinel-token-server

pom.xml

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion> <groupId>com.lee.sentinel.tokenserver</groupId><artifactId>sentinel-token-server</artifactId><version>0.0.1-SNAPSHOT</version><name>sentinel-token-server</name><description>Demo project for Spring Boot</description><properties><java.version>1.8</java.version><spring-boot.version>2.3.7.RELEASE</spring-boot.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId><exclusions><exclusion><groupId>com.alibaba.spring</groupId><artifactId>spring-context-support</artifactId></exclusion></exclusions></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId> </dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><!--slf4j--><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId></dependency> <!--nacos配置中心--><dependency><groupId>com.alibaba.boot</groupId><artifactId>nacos-config-spring-boot-starter</artifactId><version>0.2.12</version><!--由于jar包冲突，此处排除冲突jar，重新导入高版本jar--><!--nacos-spring-context-1.1.1.jar需要比spring-context-support-1.0.8.jar更高版本的jar--><exclusions><exclusion><groupId>com.alibaba.spring</groupId><artifactId>spring-context-support</artifactId></exclusion></exclusions></dependency><!--重新引入jar包--><dependency><groupId>com.alibaba.spring</groupId><artifactId>spring-context-support</artifactId><version>1.0.11</version></dependency><!--sentinel-cluster--><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-cluster-server-default</artifactId><version>1.8.5</version></dependency> <!--sentinel dashboard--><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-transport-simple-http</artifactId><version>1.8.5</version></dependency><!--sentinel dashboard -> nacos 配置动态感知--><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-datasource-nacos</artifactId><version>1.8.5</version></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>${spring-boot.version}</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

application.properties

server.port=9009
#应用名称
spring.application.name=sentinel-token-server
#nacos config center
nacos.config.server-addr=192.168.1.105:8848

ClusterServer启动类


import java.util.HashSet;
import java.util.Set;import com.alibaba.csp.sentinel.cluster.server.ClusterTokenServer;
import com.alibaba.csp.sentinel.cluster.server.SentinelDefaultTokenServer;
import com.alibaba.csp.sentinel.cluster.server.config.ClusterServerConfigManager;
import com.alibaba.csp.sentinel.cluster.server.config.ServerTransportConfig;public class ClusterServer {private static final int TOKEN_SERVER_PORT = 7777;private static final int IDLE_SECONDS = 600;public static void main(String[] args) throws Exception {ClusterTokenServer tokenServer = new SentinelDefaultTokenServer();ServerTransportConfig serverConfig = new ServerTransportConfig(TOKEN_SERVER_PORT, IDLE_SECONDS); ClusterServerConfigManager.loadGlobalTransportConfig( serverConfig ); //可以设置多个namespaceSet<String> namespaceSet = new HashSet<String>();namespaceSet.add("user-service"); //dataId=user-service-flow-rulesClusterServerConfigManager.loadServerNamespaceSet( namespaceSet ); tokenServer.start();}
}

SpringBoot启动类：

基于spring-boot SPI机制初始化限流规则：

ClusterTokenInitFunc：从

import java.util.List;import com.alibaba.csp.sentinel.cluster.flow.rule.ClusterFlowRuleManager;
import com.alibaba.csp.sentinel.datasource.ReadableDataSource;
import com.alibaba.csp.sentinel.datasource.nacos.NacosDataSource;
import com.alibaba.csp.sentinel.init.InitFunc;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;public class ClusterTokenInitFunc implements InitFunc {private String remoteAddress = "192.168.1.105:8848";// nacos配置中心地址private String groupId = "SENTINEL_GROUP";private String dataId_postfix = "-flow-rules";@Overridepublic void init() throws Exception {// TODO Auto-generated method stubloadFlowRuleByNacos();}private void loadFlowRuleByNacos() {// TODO Auto-generated method stub// 从Nacos上获取配置进行加载ClusterFlowRuleManager.setPropertySupplier(namespace -> {// namespace在ClusterServer.java中已配置String dataId = namespace + dataId_postfix; // user-service-flow-rules、 coupon-service-flow-rulesReadableDataSource<String, List<FlowRule>> readableDataSource = new NacosDataSource<>(remoteAddress,groupId, dataId, source -> JSON.parseObject(source, new TypeReference<List<FlowRule>>() {}));return readableDataSource.getProperty();});}}

其中，我的Nacos配置（dataId=user-service-flow-rules）设置如下：

[{"resource":"com.lee.demo.dubbo.demo.user.ISentinelService","grade":1,"count":2,"clusterMode":true,"clusterConfig":{"flowId":"1001","thresholdType":1,"fallbackToLocalWhenFail":true}},{"resource":"com.lee.demo.dubbo.demo.user.IHelloService","grade":1,"count":30,"clusterMode":true,"clusterConfig":{"flowId":"1002","thresholdType":1,"fallbackToLocalWhenFail":true}}
]

至此sentinel-token-server搭建完成，启动服务

2. 配置客户端Token Client

导包

        <!--nacos配置中心--><dependency><groupId>com.alibaba.boot</groupId><artifactId>nacos-config-spring-boot-starter</artifactId><version>0.2.12</version><!--由于jar包冲突，此处排除冲突jar，重新导入高版本jar--><!--nacos-spring-context-1.1.1.jar需要比spring-context-support-1.0.8.jar更高版本的jar--><exclusions><exclusion><groupId>com.alibaba.spring</groupId><artifactId>spring-context-support</artifactId></exclusion></exclusions></dependency><!--重新引入jar包--><dependency><groupId>com.alibaba.spring</groupId><artifactId>spring-context-support</artifactId><version>1.0.11</version></dependency><!--sentinel-dubbo-adapter --><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-apache-dubbo-adapter</artifactId><version>1.8.5</version></dependency><!--sentinel dashboard--><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-transport-simple-http</artifactId><version>1.8.5</version></dependency><!--sentinel dashboard -> nacos 配置动态感知--><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-datasource-nacos</artifactId><version>1.8.5</version></dependency><!--sentinel-token-cluster--><dependency><groupId>com.alibaba.csp</groupId><artifactId>sentinel-cluster-client-default</artifactId><version>1.8.5</version></dependency>

加载集群流控规则：

ClusterFlowRuleInitFunc.java

import java.util.List;import com.alibaba.csp.sentinel.cluster.ClusterStateManager;
import com.alibaba.csp.sentinel.cluster.client.config.ClusterClientAssignConfig;
import com.alibaba.csp.sentinel.cluster.client.config.ClusterClientConfig;
import com.alibaba.csp.sentinel.cluster.client.config.ClusterClientConfigManager;
import com.alibaba.csp.sentinel.datasource.Converter;
import com.alibaba.csp.sentinel.datasource.ReadableDataSource;
import com.alibaba.csp.sentinel.datasource.nacos.NacosDataSource;
import com.alibaba.csp.sentinel.init.InitFunc;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;public class ClusterFlowRuleInitFunc implements InitFunc{private static final String CLUSTER_SERVER_HOST = "localhost";private static final int CLUSTER_SERVER_PORT = 7777;private static final int REQUEST_TIME_OUT = 20000;private static final String remoteAddress = "192.168.1.105:8848";private static final String groupId = "SENTINEL_GROUP";  private static final String FLOW_POSTFIX="-flow-rules";private static final String APP_NAME="user-service";@Overridepublic void init() throws Exception {// TODO Auto-generated method stub//声明为Token ClientClusterStateManager.applyState(ClusterStateManager.CLUSTER_CLIENT);//加载集群限流Token Server loadClusterClientConfig(); //加载单机限流规则（如果Token Server不可用，退化到单机限流）initFlowRulesWithDatasource(); }/*** 集群限流规则* */private void loadClusterClientConfig() {ClusterClientAssignConfig assignConfig  = new ClusterClientAssignConfig();assignConfig.setServerHost(CLUSTER_SERVER_HOST);assignConfig.setServerPort(CLUSTER_SERVER_PORT);ClusterClientConfigManager.applyNewAssignConfig(assignConfig);ClusterClientConfig clientConfig = new ClusterClientConfig();clientConfig.setRequestTimeout(REQUEST_TIME_OUT);ClusterClientConfigManager.applyNewConfig(clientConfig);}/*** 单机限流规则* */private void initFlowRulesWithDatasource() {  String dataId = APP_NAME + FLOW_POSTFIX;
//		ReadableDataSource<String, List<FlowRule>> readableDataSource = new NacosDataSource<>(
//				remoteAddress, groupId, dataId
//				,source->JSON.parseObject(source,new TypeReference<List<FlowRule>>() {}));ReadableDataSource<String, List<FlowRule>> readableDataSource = new NacosDataSource<>(remoteAddress, groupId, dataId, new Converter<String, List<FlowRule>>() { @Overridepublic List<FlowRule> convert(String source) {// TODO Auto-generated method stubSystem.out.println("source:"+source); List<FlowRule> rules = JSON.parseObject(source,new TypeReference<List<FlowRule>>() {}); return rules;}});    FlowRuleManager.register2Property(readableDataSource.getProperty());} }

Controller:

至此，Token Client配置完成。

接下来启动3个客户端，模拟集群：

Sentinel-Dashboard上可以看到user-service有三台集群机器：

使用jmeter压测工具进行压测：

压测结果如下，可以看到com.lee.demo.dubbo.demo.user.ISentinelService.testSentinel() 接口的qps一直不会超过6个请求，这个峰值是怎么计算的来的呢？因为我上面提到的Nacos集群限流配置dataId=user-service-flow-rules中配置com.lee.demo.dubbo.demo.user.ISentinelService的qps=2，而我们总共有3台机器，因此集群限流max qps：2x3=6