与Spring Cloud Alibaba 开源负责人一起深入理解 Sentinel实现熔断与限流
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：
2.流控规则:
基本介绍
超过 1次/s:将会报
2.1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
2.2 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
3.流控效果:
3.1预热
应用场景：
3.2.排队等待
降级规则：
1 RT
效果演示：
2：异常比例
效果演示：
3：异常数：
效果演示：
热点key限流：
官网：https://github.com/alibaba/Sentinel/wiki/热点参数限流
效果演示：
错误页面：（无blockHandler的兜底方法）
4.参数例外项
手动异常：
结论：
系统规则：(系统入口的限流，而非细粒度的rest)*
官网：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
@SentinelResource
增加的流控规则随着关闭8401,流控规则消失----------》解决需要规则持久化
无兜底方法;
客户自定义限流处理逻辑:
5.服务熔断功能（重要）
1：ribbon系列：
9003和9004的
ymL:
84:
案例2;
效果：
案例3：
两者都配的结论：在QPS的合理配置内，走fallback，一旦超出合理配置则走bloackHandler
2：feign系类：
大纲：
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
datasource:
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
主启动类：
业务代码：
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
熔断框架的区别:
3.规则持久化；
大纲：
修改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>
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
datasource:
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
快速访问测试接口:
停止8401再看sentinel:
重启8401：
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