hystrix和sentinel简笔

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hystrix和sentinel简笔

简介
技术栈
熔断
- 导入maven
- yml配置
- 配置启动相关数据
- 代码演示
- 验证正确性
限流
- 下载监控
- 添加配置
- 代码演示
- 验证代码
源码
参考文献

简介

在分布式系统开发时，会面临一序列问题，比如雪崩效应。特别是高并发没法处理请求或者接口异常情况下，我们需要降级请求，防止出现雪崩效应。此外，在一些并发系统的情况下，个别接口需要进行限流，防止大量并发占用别的接口服务资源，基于此个人便捷记录熔断和限流笔记！

技术栈

hystrix
java
hystrix-dashboard
maven
idea pc
sentinel

熔断

目前居于原有项目的user-center模块开发，分支为feat/hystrix

导入maven

目前使用hystrix和dashboard，因此此时需要导入actuator

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-hystrix</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId></dependency>

yml配置

需要配置暴露地址和hystrix熔断时间以及代理允许监控的上报服务器ip

hystrix:dashboard:proxy-stream-allow-list: localhostmetrics:enabled: truecommand:default:execution:isolation:thread:timeoutInMilliseconds: 5000
management:endpoints:web:base-path: /actuatorexposure:include: '*'

配置启动相关数据

需要@EnableHystrixDashboard启动仪表，@EnableCircuitBreaker启动熔断，此外，由于仪表需要页面，目前新版本没有启动。

@SpringBootApplication
@MapperScan("com.lgh.mapper")
@EnableSwagger2
@EnableFeignClients
@EnableEurekaClient
@EnableHystrixDashboard
@EnableCircuitBreaker
public class RunApplication {public static void main(String[] args) {SpringApplication.run(RunApplication.class, args);}
}

新版本@EnableHystrixDashboard在启动类配置外，还需要配置web页面

 @Overridepublic void addResourceHandlers(ResourceHandlerRegistry registry) {registry.addResourceHandler("/static/**").addResourceLocations("classpath:/static/");registry.addResourceHandler("swagger-ui.html").addResourceLocations("classpath:/META-INF/resources/");registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/");registry.addResourceHandler("/hystrix/**").addResourceLocations("classpath:/static/hystrix/");}

代码演示

目前注解@HystrixCommand启动熔断，使用fallbackMethod友好降级。

@Service
public class HystrixDemoImpl implements IHystrixDemo {@HystrixCommand(fallbackMethod = "fallbackMethod")@Overridepublic String test(String inputStr) {try {System.out.println("test Hystrix");Thread.sleep(4000);} catch (InterruptedException e) {e.printStackTrace();}return "SUCCESS";}public String fallbackMethod(String inputStr) {System.out.println("fallbackMethod");return "Time out" + inputStr;}
}@Api(tags = "熔断限流测试")
@RestController
@RequestMapping("/hystrixtest")
public class HystrixController {@Autowiredprivate IHystrixDemo iHystrixDemo;@GetMapping("/test")public String test(String inputStr) {return iHystrixDemo.test(inputStr);}
}

验证正确性

查看hystrix-dashboard是否生效http://localhost:8088/hystrix，接着输入监控地址：http://localhost:8088/actuator/hystrix.stream，点击Monitor Stream即可，若没数据，则需要请求才有数据，如下图
在这里插入图片描述
接下来使用jmeter并发请求，具体下载地址：jmeter配置完直接执行

查看控制台日志或者打断点看熔断情况：

限流

限流比较简单使用，具体可以参考alibaba官网。sentinel

下载监控

直接官网下载sentinel-dashboard，具体操作官网有详解。打包完jar包后，启动命令：

java -Dserver.port=8080  -Dcsp.sentinel.dashboard.server=localhost:8080  -Dproject.name=sentinel-dashboard  -jar target/sentinel-dashboard.jar

浏览监控http://localhost:8080/
在这里插入图片描述

添加配置

主要pom导入和限流aop配置，具体如下(更多版本参考https://mvnrepository.com/)
pom：

  <dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-sentinel</artifactId><version>2.2.5.RELEASE</version></dependency>

SentinelResourceAspect配置

import com.alibaba.csp.sentinel.annotation.aspectj.SentinelResourceAspect;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;@Configuration
public class SentinelConfig {@Beanpublic SentinelResourceAspect sentinelResourceAspect() {return new SentinelResourceAspect();}
}

上报sentinel-dashboard的配置，sentinel-dashboard上可动态配置规则

spring:cloud:sentinel:transport:dashboard: 127.0.0.1:8080enabled: true

代码演示

这里主要处理限流异常处理类和实现注解@SentinelResource
阻塞异常处理：

package com.lgh.exception;import com.alibaba.csp.sentinel.slots.block.BlockException;public class ExceptionUtil {public static String handleException(String inputStr, BlockException ex) {System.out.println("Oops: " + ex.getClass().getCanonicalName());return "Fail";}
}

异常实现类HystrixDemoImpl

package com.lgh.service.impl;import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.lgh.exception.ExceptionUtil;
import com.lgh.service.IHystrixDemo;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.stereotype.Service;@Service
public class HystrixDemoImpl implements IHystrixDemo {@SentinelResource(value = "testSentinel",blockHandler = "handleException", blockHandlerClass = ExceptionUtil.class)@Overridepublic String testSentinel(String inputStr) {try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}return "SUCCESS";}
}

controller请求处理HystrixController

package com.lgh.controller;import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.lgh.service.IHystrixDemo;
import io.swagger.annotations.Api;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@Api(tags = "熔断限流测试")
@RestController
@RequestMapping("/hystrixtest")
public class HystrixController {@Autowiredprivate IHystrixDemo iHystrixDemo;@GetMapping("/testSentinel")public String testSentinel(String inputStr) {return iHystrixDemo.testSentinel(inputStr);}
}