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17 07 月 2020

雪崩效应与熔断机制

雪崩效应：服务提供者的不可用原因导致服务调用者的不可用结果，并且不可用的状态逐渐放大的现象。

3.1、Hystrix熔断器

Hystrix（豪猪）是Netflix开源的熔断器组件，用于为微服务提供熔断机制预防雪崩，保护整体微服务架构的健康。

Hystrix功能

  • 预防微服务由于故障，请求长时间等待导致Web容器线程崩溃
  • 提供故障备选方案，通过回退（fallback)机制提供”服务降级”
  • 提供监控仪表盘，实时监控运行状态

Hystrix工作原理

Hystrix组件用于调用者一方，如上图，在工资核算调用员工管理微服务，Hystrix配置在工资核算服务中。Hystrix有三种状态：Closed、OPEN、HALF-OPEN，默认状态是Closed，一个Rolling Window(滑动窗口）的时间内（默认：10秒），最近20次请求中，错误率(服务降级)若超过50%,则触发熔断5秒，期间快速失败。此时Hystrix状态会变为Open，当5秒熔断窗口期过了，此时工资核算服务向员工管理服务发送一个请求，此时Hystrix状态转为HALF-OPEN，如果此次请求成功（1s内），则Hystrix状态转为CLOSED,反之则重新转为OPEN。

触发服务降级的情况

  • FAILURE: 执行失败，抛出异常
  • TIMEOUT: 执行超时（默认1秒）
  • SHORT_CIRCUITED: 熔断器状态为Open
  • THREAD_POOL_REJECTED: 线程池拒绝
  • SEMAPHORE_REJECTED: 信号量拒绝
3.2、RestTemplate与Hystrix整合

模拟业务场景：图书到货通知，会员管理服务，请求短信服务发送短信通知会员，新书已到。

创建短信服务

  1. 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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.15.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.codesofun</groupId>
    <artifactId>message-service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>message-service</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR6</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </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>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.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>

  2. application.properties配置

    spring.application.name=message-service
eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

  3. 启动类中添加注解@EnableEurekaClient

    package com.codesofun.messageservice;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient
public class MessageServiceApplication {

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

  4. 实体类CallBackResult

    package com.codesofun.messageservice.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
 * @ClassName CallBackResult
 * @Description
 * @Author mozhijun
 * @Date 2020/7/7 14:35
 * @Version 1.0
 **/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class CallBackResult {
    private Integer code;
    private String message;
}

  5. controller层

    package com.codesofun.messageservice.controller;

import com.codesofun.messageservice.entity.CallBackResult;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.Random;

/**
 * @ClassName MessageController
 * @Description
 * @Author mozhijun
 * @Date 2020/7/7 14:33
 * @Version 1.0
 **/
@RestController
public class MessageController {

    /**
     * 描述: 模拟发送短信
     * @Author mozhijun
     * @Date 15:09 2020/7/7
     * @param mobile 手机号
     * @param message 发送的消息
     * @return com.codesofun.messageservice.entity.CallBackResult
     */
    @GetMapping("/sendMessage")
    public CallBackResult sendMessage(String mobile,String message){
        //模拟堵塞的情景（雪崩效应）
        int seconds = new Random().nextInt(3000);
        try {
            Thread.sleep(seconds);
            if (seconds > 1000) {
                return new CallBackResult(-1,"fail");
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return new CallBackResult(0,"success");
    }
}

**Member-Service**服务中修改

  1. pom.xml添加依赖

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

  2. 创建实体类CallBackResult

    package com.codesofun.memberservice.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
 * @ClassName CallBackResult
 * @Description
 * @Author mozhijun
 * @Date 2020/7/7 14:35
 * @Version 1.0
 **/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class CallBackResult {
    private Integer code;
    private String message;
}

  3. 启动类中添加注解@EnableHystrix

  4. MemberController中添加接口

        /**
     * 模拟新书稻花短信通知客户的业务
     */
    @GetMapping("/snb")
    @HystrixCommand(fallbackMethod = "sendMessageError") //提供熔断与服务降级
    public String sendNewBook(String mobile,String bookname){
        String message = "[CODESOFUN]您预购的" + bookname + "已到货，明日将送到您府上";
        CallBackResult result = restTemplate.getForObject("http://message-service/sendMessage?mobile=" +mobile+"&message=" + message , CallBackResult.class);
        if (result.getCode().equals(0)){
            return "短信已成功送达，服务返回：" +result.getMessage();
        }else {
            return "短信发送失败，失败原因:" + result.getMessage();
        }
    }

    public String sendMessageError(String mobile,String bookname){
        return "短信发送失败，失败原因：消息服务无法正常运行，请稍后再试";
    }

  5. 浏览器请求：http://localhost:9000/snb?mobile=11111&bookname=xxxx进行测试

3.3、OpenFeign与Hystrix整合

使用步骤

  • OpenFeign内置Hystrix，feign.hystrix.enable开启即可
  • 在@FeignClient增加fallback属性说明Fallback类
  • Fallback类要实现相同接口，重写服务降级业务逻辑

**Member-Service-Openfeign**服务中修改

  1. application.properties中添加配置

    #开启熔断机制，feign 组件中默认整合hystrix组件，需要开启
feign.hystrix.enabled=true

  2. 创建实体类CallBackResult

    package com.codesofun.memberservice.openfeign.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
 * @ClassName CallBackResult
 * @Description
 * @Author mozhijun
 * @Date 2020/7/7 14:35
 * @Version 1.0
 **/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class CallBackResult {
    private Integer code;
    private String message;
}

  3. 创建MessageService服务

    package com.codesofun.memberservice.openfeign.service;

import com.codesofun.memberservice.openfeign.entity.CallBackResult;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

/**
 * @Author: 小莫
 * @Date: 2020-07-07 16:20
 * @Description TODO
 */
@FeignClient(value = "message-service",fallback = MessageServiceFallback.class)
public interface MessageService {

    @GetMapping("/sendMessage")
    CallBackResult sendMessage(@RequestParam("mobile") String mobile, @RequestParam("message") String message);
}

  4. Fallback类要实现相同接口，重写服务降级业务逻辑

    package com.codesofun.memberservice.openfeign.service;

import com.codesofun.memberservice.openfeign.entity.CallBackResult;
import org.springframework.stereotype.Component;

/**
 * @ClassName MessageServiceFallback
 * @Description
 * @Author mozhijun
 * @Date 2020/7/7 16:22
 * @Version 1.0
 **/
@Component
public class MessageServiceFallback implements MessageService{

    /**
     * 熔断机制，返回提示
     */
    @Override
    public CallBackResult sendMessage(String mobile, String message) {
        return new CallBackResult(-1,"消息服务无法正常运行，请稍后再试");
    }
}

  5. MemberServiceOpenfeignController中新增接口

        /**
     * 模拟新书稻花短信通知客户的业务
     */
    @GetMapping("/snb")
    public String sendNewBook(String mobile,String bookname){
        String message = "[CODESOFUN]您预购的" + bookname + "已到货，明日将送到您府上";
        CallBackResult result =  messageService.sendMessage(mobile,message);
        if (result.getCode().equals(0)){
            return "短信已成功送达，服务返回：" +result.getMessage();
        }else {
            return "短信发送失败，失败原因:" + result.getMessage();
        }	
    }

  6. 浏览器请求：http://localhost:9000/snb?mobile=11111&bookname=xxxx进行测试

3.4、Hystrix超时设置
超时配置选项说明
feign.client.config.[微服务ID\default].connectTimeoutRibbon连接超时时间默认1秒，建议1秒内
feign.client.config.[微服务ID\default]Ribbon读取超时时间默认1秒，按业务处理时间设置
hystrix.command.[commandKey\default].execution.isolation.thread.timeoutInMillisecondsHystrix熔断超时时间默认1秒
hystrix.command.[commandKey\default].circuitBreaker.forceOpen强制打开熔断器默认关闭，服务下线时手动开启

**备注：**熔断器超时时间 ≥ connectTimeout(连接时间) + readTimeout（业务处理/读取时间）

3.5、Hystrix熔断设置项
超时选项说明
hystrix.command.default.circuitBreaker.requestVolumeThreshold最近调用次数，默认: 20
hystrix.command.default.circuitBreaker.errorThresholdPercentage请求错误率，默认：50
hystrix.command.default.metrics.rollingStats.timeInMilliseconds滑动窗口期，默认：10000
hystrix.command.default.circuitBreaker.sleepWindowInMilliseconds熔断持续时间：5000

**application.properties**中配置如下：

############# 连接时长1000毫秒，等待响应时间（业务处理）设置 4000毫秒，熔断机制设置时间 1000毫秒，哪个时间timeout就会触发熔断
#开启熔断机制，feign 组件中默认整合hystrix组件，需要开启
feign.hystrix.enabled=true
#客户端向微服务发起连接的最长等待时间
feign.client.config.default.connect-timeout=500
#连接后，等待响应返回的最长时间 (3000-2500)/3000 = 16.7% ; (1000-500)/1000 = 50%
feign.client.config.default.read-timeout=500
#指定具体的message-service微服务设置熔断时间，格式：类名#方法名(参数类型1,参数类型2...参数类型n)
hystrix.command.MessageService#sendMessage(String,String).execution.isolation.thread.timeoutInMilliseconds=1000
#所有微服务默认熔断时间
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds=6000
#指定具体的book-service微服务设置连接以及相应时间
feign.client.config.book-service.connect-timeout=5000
feign.client.config.book-service.read-timeout=5000
#强制熔断器处于open状态，即设置服务不可用，直接服务降级。默认为false,这里注意：当服务正常以后需要设置为false
hystrix.command.circuitBreaker.forceOpen=true

#最近50次调用请求
hystrix.command.MessageService#sendMessage(String,String).circuitBreaker.requestVolumeThreshold=50
#请求错误率超过60%
hystrix.command.MessageService#sendMessage(String,String).circuitBreaker.errorThresholdPercentage=60
#触发熔断10秒
hystrix.command.MessageService#sendMessage(String,String).circuitBreaker.sleepWindowInMilliseconds=10000
#最近20秒统计
hystrix.command.MessageService#sendMessage(String,String).metrics.rollingStats.timeInMilliseconds=20000

#hystrix 默认熔断参数配置（在最近20秒内，请求错误率超过百分之六十，则触发熔断10秒，期间快速失败）
#最近50次调用请求
hystrix.command.default.circuitBreaker.requestVolumeThreshold=50
#请求错误率超过60%
hystrix.command.default.circuitBreaker.errorThresholdPercentage=60
#触发熔断10秒
hystrix.command.default.circuitBreaker.sleepWindowInMilliseconds=10000
#最近20秒统计
hystrix.command.default.metrics.rollingStats.timeInMilliseconds=20000
3.6、部署Hystrix Dashboard监控

Hystrix Dashboard使用步骤

  • Hystrix Client依赖hystrix-metrics-event-stream
  • Hystrix Client注册HystrixMetricsStreamServlet
  • 监控微服务依赖spring-cloud-starter-netflix-hystrix-dashboard
  • 监控微服务利用@EnableHystrixDashboard开启仪表盘

  1. pom.xml配置依赖

            <dependency>
            <groupId>com.netflix.hystrix</groupId>
            <artifactId>hystrix-metrics-event-stream</artifactId>
            <version>1.5.18</version>
        </dependency>

  2. 注册HystrixMetricsStreamServlet

        /**
     * hystrix对外提供数据接口
     */
    @Bean
    public ServletRegistrationBean hystrixServlet(){
        HystrixMetricsStreamServlet servlet = new HystrixMetricsStreamServlet();
        ServletRegistrationBean bean = new ServletRegistrationBean(servlet);
        //url
        bean.addUrlMappings("/hystrix.stream");
        //实例名称
        bean.setName("HystrixMetricsStreamServlet");
        //启动顺序
        bean.setLoadOnStartup(1);
        return bean;
    }

  3. 监控微服务依赖spring-cloud-starter-netflix-hystrix-dashboard

    pom.xml中添加依赖

    <?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.15.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.codesofun</groupId>
    <artifactId>hystrix-dashboard</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>hystrix-dashboard</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR6</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.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中添加配置

    server.port=8081
spring.application.name=hystrix-dashboard
eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

    监控微服务利用@EnableHystrixDashboard开启仪表盘，启动类中添加注解@EnableHystrixDashboard

    package com.codesofun.hystrix.dashboard;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;

@SpringBootApplication
@EnableHystrixDashboard
public class HystrixDashboardApplication {

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

详细代码见仓库：https://gitee.com/xmlvhy/springcloud-learn 参考链接：http://www.itlaoqi.com/

本文作者： AI码真香

本文标题： SpringCloud入门系列之雪崩效应与熔断机制

本文网址： https://www.xmlvhy.com/article/90.html

版权说明： 自由转载-非商用-非衍生-保持署名 署名-非商业性使用4.0 国际 (CC BY-NC 4.0)

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