SpringCloudHystrix熔断器使用方法介绍

2023-03-20 11:03:53 介绍熔断器使用方法

Hystrix(hi si ju ke si)概述

Hystix 是 Netflix 开源的一个延迟和容错库，用于隔离访问远程服务、第三方库，防止出现级联失败（雪崩）。

雪崩：一个服务失败，导致整条链路的服务都失败的情形。

Hystix 主要功能

隔离
降级
熔断
限流

隔离

线程池隔离
信号量隔离

Hystrix 降级

Hystix 降级：当服务发生异常或调用超时，返回默认数据

Hystrix降级-服务提供方

在服务提供方，引入 hystrix 依赖
定义降级方法
使用 @HystrixCommand 注解配置降级方法
在启动类上开启Hystrix功能：@EnableCircuitBreaker

初始化程序和Fiegn程序一致

需要修改的程序

package com.itheima.provider;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@EnableEurekaClient //该注解 在新版本中可以省略
@SpringBootApplication
@EnableCircuitBreaker ///开启Hystrix功能
public class ProviderApp {
    public static void main(String[] args) {
        SpringApplication.run(ProviderApp.class,args);
    }
}

测试的程序

package com.itheima.provider.controller;
import com.itheima.provider.domain.Goods;
import com.itheima.provider.service.GoodsService;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.WEB.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.Date;

@RestController
@RequestMapping("/goods")
public class GoodsController {
    @Autowired
    private GoodsService goodsService;
    @Value("${server.port}")
    private int port;
    
    @GetMapping("/findOne/{id}")
    @HystrixCommand(fallbackMethod = "findOne_fallback",commandProperties = {
            //设置Hystrix的超时时间 默认1s
            @HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds",value = "3000")
    })///指定降级后的方法
    public Goods findOne(@PathVariable("id") int id)  {
        ///1 造个异常
        //int i =3/0;
        try {
            Thread.sleep(2000);//sleep interrupted
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        Goods goods = goodsService.findOne(id);
        goods.setTitle(goods.getTitle() + ":" + port);//将端口号，设置到了 商品标题上
        return goods;
    }
    
    public Goods findOne_fallback(int id) {
        Goods goods = new Goods();
        goods.setTitle("降级了~~~");
        return goods;
    }
}

指定坐标

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

Hystrix降级-服务消费方

feign 组件已经集成了 hystrix 组件。
定义feign 调用接口实现类，复写方法，即降级方法
在 @FeignClient 注解中使用 fallback 属性设置降级处理类。
配置开启 feign.hystrix.enabled = true

provider与Fiegin一致

application.yml修改

server:
port: 9000

eureka:
instance:
hostname: localhost # 主机名
client:
service-url:
defaultZone: Http://localhost:8761/eureka
spring:
application:
name: hystrix-consumer # 设置当前应用的名称。将来会在eureka中Application显示。将来需要使用该名称来获取路径
#开启feign对hystrix支持
feign:
hystrix:
enabled: true

ConsumerApp修改

package com.itheima.consumer;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
@EnableDiscoveryClient // 激活DiscoveryClient
@EnableEurekaClient
@SpringBootApplication
@EnableFeignClients //开启Feign的功能
public class ConsumerApp {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerApp.class,args);
    }
}

修改GoodsFeignClient方法

package com.itheima.consumer.feign;
import com.itheima.consumer.domain.Goods;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
@FeignClient(value = "HYSTRIX-PROVIDER",fallback = GoodsFeignClientFallback.class)
public interface GoodsFeignClient {
    @GetMapping("/goods/findOne/{id}")
    public Goods findGoodsById(@PathVariable("id") int id);
}

复写方法

package com.itheima.consumer.feign;
import com.itheima.consumer.domain.Goods;
import org.springframework.stereotype.Component;

@Component
public class GoodsFeignClientFallback implements  GoodsFeignClient{
    @Override
    public Goods findGoodsById(int id) {
        Goods goods = new Goods();
        goods.setTitle("又被降级了~~");
        return goods;
    }
}

Hystrix 熔断

Hystrix 熔断机制，用于监控微服务调用情况，当失败的情况达到预定的阈值（5秒失败20次），会打开断路器，拒绝所有请求，直到服务恢复正常为止。

circuitBreaker.sleepWindowInMilliseconds：监控时间
circuitBreaker.requestVolumeThreshold：失败次数
circuitBreaker.errorThresholdPercentage：失败率

//设置Hystrix的超时时间 默认1s
@HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds",value = "3000"),
//监控的时间 默认5000ms
@HystrixProperty(name="circuitBreaker.sleepWindowInMilliseconds",value = "1000"),
//失败次数，默认20次
@HystrixProperty(name="circuitBreaker.requestVolumeThreshold",value = "2"),
//失败率 百分之50
@HystrixProperty(name="circuitBreaker.errorThresholdPercentage",value = "100")

Hystrix 熔断监控

Hystrix 提供了 Hystrix-dashboard 功能，用于实时监控微服务运行状态。
但是Hystrix-dashboard只能监控一个微服务。
Netflix 还提供了 Turbine ，进行聚合监控。

Turbine聚合监控

搭建监控模块

1. 创建监控模块

创建hystrix-monitor模块，使用Turbine聚合监控多个Hystrix dashboard功能,

2. 引入Turbine聚合监控起步依赖

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>hystrix-parent</artifactId>
        <groupId>com.itheima</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>hystrix-monitor</artifactId>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
    	<!--单独熔断监控-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId>
        </dependency>
		<!--聚合熔断监控-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-turbine</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

3. 修改application.yml

spring:
application.name: hystrix-monitor
server:
port: 8769
turbine:
combine-host-port: true
# 配置需要监控的服务名称列表
app-config: hystrix-provider,hystrix-consumer
cluster-name-expression: "'default'"
aggregator:
cluster-config: default
#instanceUrlSuffix: /actuator/hystrix.stream
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/

4. 创建启动类

@SpringBootApplication
@EnableEurekaClient
@EnableTurbine //开启Turbine 很聚合监控功能
@EnableHystrixDashboard //开启Hystrix仪表盘监控功能
public class HystrixMonitorApp {
    public static void main(String[] args) {
        SpringApplication.run(HystrixMonitorApp.class, args);
    }
}

修改被监控模块

需要分别修改 hystrix-provider 和 hystrix-consumer 模块：

1、导入依赖：

		<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>

2、配置Bean

此处为了方便，将其配置在启动类中。

@Bean
    public ServletReGIStrationBean getServlet() {
        HystrixMetriCSStreamServlet streamServlet = new HystrixMetricsStreamServlet();
        ServletRegistrationBean registrationBean = new ServletRegistrationBean(streamServlet);
        registrationBean.setLoadOnStartup(1);
        registrationBean.addUrlMappings("/actuator/hystrix.stream");
        registrationBean.setName("HystrixMetricsStreamServlet");
        return registrationBean;
    }

3、启动类上添加注解@EnableHystrixDashboard

@EnableDiscoveryClient
@EnableEurekaClient
@SpringBootApplication
@EnableFeignClients 
@EnableHystrixDashboard // 开启Hystrix仪表盘监控功能
public class ConsumerApp {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerApp.class,args);
    }
    @Bean
    public ServletRegistrationBean getServlet() {
        HystrixMetricsStreamServlet streamServlet = new HystrixMetricsStreamServlet();
        ServletRegistrationBean registrationBean = new ServletRegistrationBean(streamServlet);
        registrationBean.setLoadOnStartup(1);
        registrationBean.addUrlMappings("/actuator/hystrix.stream");
        registrationBean.setName("HystrixMetricsStreamServlet");
        return registrationBean;
    }
}

启动测试

1、启动服务：

eureka-server
hystrix-provider
hystrix-consumer
hystrix-monitor

2、访问：

在浏览器访问http://localhost:8769/hystrix/ 进入Hystrix Dashboard界面

界面中输入监控的Url地址 http://localhost:8769/turbine.stream，监控时间间隔2000毫秒和title，如下图

实心圆：它有颜色和大小之分，分别代表实例的监控程度和流量大小。如上图所示，它的健康度从绿色、黄色、橙色、红色递减。通过该实心圆的展示，我们就可以在大量的实例中快速的发现故障实例和高压力实例。
曲线：用来记录 2 分钟内流量的相对变化，我们可以通过它来观察到流量的上升和下降趋势。

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