官网：https://github.com/alibaba/Sentinel

中文：https://github.com/alibaba/Sentinel/wiki/%E4%BB%8B%E7%BB%8D

下载：https://github.com/alibaba/Sentinel/releases

运行：

1  初始化演示工程

1.1 大纲；

1.2  创建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>cloud2020</artifactId>
        <groupId>com.eiletxie.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloudalibaba-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><!-- 引用自己定义的api通用包，可以使用Payment支付Entity -->
            <groupId>com.eiletxie.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </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.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>
    </dependencies>
</project>

yml:

server:
  port: 8401

spring:
  application:
    name: cloudalibaba-sentinal-service
  cloud:
    nacos:
      discovery:
        #Nacos服务注册中心地址
        server-addr: localhost:8848
    sentinel:
      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
management:
  endpoints:
    web:
      exposure:
        include: ‘*‘

localhost:8080 控制台的地址，指定控制台后客户端会自动向该地址发送心跳包 

(默认8719) 客户端提供给Dashboard访问或者查看Sentinel的运行访问的参数

主启动类：

/**
 * @Author EiletXie
 * @Since 2020/3/17 12:52
 */
@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401 {

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

controller:

package com.eiletxie.springcloud.alibaba.controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.concurrent.TimeUnit;

/**
 * @Author EiletXie
 * @Since 2020/3/17 12:54
 */
@RestController
@Slf4j
public class FlowLimitController {

    @GetMapping("/testA")
    public String testA() {
        return "----testA";
    }

    @GetMapping("/testB")
    public String testB() {
        return "----testB";
    }
}

空空如也：

执行：

结果：

流控规则:

基本介绍

    超过 1次/s:将会报       

 1 直接：api达到限流条件时，直接限流

阀值类型的QPS和线程数的区别：

         QPS (每秒钟的请求数量) :当调用该api的QPS达到阈值的时候，进行限流

        线程数:当调用该api的线程数达到阈值的时候，进行限流

去掉暂停毫秒的代码，就是普通的QPS的模拟

2 关联: 当关联的资源达到阈值时，就限流自己

模拟访问B

结论：大批量线程高并发访问B，导致A失效了

流控效果:

2 预热:

应用场景：

3：排队等待

原文地址：https://www.cnblogs.com/leeego-123/p/12706774.html