Hystrix断路器

Hystrix断路器

分布式系统面临的问题：复杂分布式体系结构中的应用程序有数十个依赖关系，每个依赖关系在某些时候将不可避免的失败。

Hystirx是一个用于处理分布式系统的延迟和容错的开源库，在分布式系统里，许多依赖不可避免的会调用失败，比如超时、异常等，Hystirx能够保证在一个依赖出问题的情况下，不会导致整体服务失败，避免级联故障，以提高分布式系统的弹性。

“断路器”本身是一种开关装置，当某个服务单元发生故障之后，通过断路器的故障监控，向调用方返回一个符合预期的、可处理的备选响应(FallBack)，而不是长时间的等待或者抛出调用方无法处理的异常，这样就保证了服务调用方的线程不会被长时间、不必要的占用，从而避免了故障在分布式系统中的蔓延，乃至雪崩。

服务降级

  • 服务器忙，请稍后再试，不让客户端等待并立即返回一个友好提示，fallback

  • 程序运行异常、超时、服务熔断触发服务降级、线程池/信号量打满也会导致服务降级。

服务熔断

  • 类似保险丝达到最大服务访问后，直接拒绝，拉闸限电，然后调用服务降级的方法并返回友好提示。

服务限流

  • 秒杀高并发等操作，严禁一窝蜂的过来拥挤，大家排队，一秒钟N个，有序进行。

Hytrix微服务架构

创建一个子项目(cloud-provider-hystrix-payment8001)

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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>cloud2020</artifactId>
        <groupId>com.atguigu.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-provider-hystrix-payment8001</artifactId>
    <dependencies>
        <!--hystrix-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <!--eureka client-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!--web-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>com.atguigu.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <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>

创建application.yml配置文件

server:
  port: 8001


spring:
  application:
    name: cloud-provider-hystrix-payment

eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka

创建主启动类(PaymentHystrixMain8001)

package com.atguigu.springcloud;

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

@SpringBootApplication
@EnableEurekaClient
public class PaymentHystrixMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentHystrixMain8001.class,args);
    }
}

创建PaymentService

package com.atguigu.springcloud.service;

import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

@Service
public class PaymentService {

    public String paymentInfo_OK(Integer id){
        return "线程池： "+Thread.currentThread().getName()+",id"+id+"***";
    }
    public String paymentInfo_Timeout(Integer id){
        int timeNumber = 3;
        try {
            TimeUnit.SECONDS.sleep(3);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "线程池： "+Thread.currentThread().getName()+",id"+id+"***,耗时"+timeNumber;
    }
}

创建PaymentController

package com.atguigu.springcloud.controller;

import com.atguigu.springcloud.service.PaymentService;
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.RestController;

import javax.annotation.Resource;

@RestController
public class PaymentController {
    @Resource
    private PaymentService paymentService;
    @Value("${server.port}")
    private String serverPort;

    @GetMapping(value = "/payment/hytrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id) {
        String result = paymentService.paymentInfo_OK(id);
        return result;
    }
    @GetMapping(value = "/payment/hytrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id) {
        String result = paymentService.paymentInfo_Timeout(id);
        return result;
    }
}

创建一个子项目(cloud-consumer-feign-hystrix-order80)

pom.xml文件

<dependencies>
        <!--openfeign-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!--hystrix-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <!--eureka client-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
        <dependency>
            <groupId>com.atguigu.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <!--web-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!--一般基础通用配置-->
        <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>

配置文件application.yml

server:
  port: 7999
eureka:
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka

主启动类OrderHystrixMain80

package com.atguigu.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableFeignClients
public class OrderHystrixMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderHystrixMain80.class,args);
    }
}

写接口PaymentHystrixService

package com.atguigu.springcloud.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT")
public interface PaymentHystrixService {
    @GetMapping(value = "/consumer/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id);
    @GetMapping(value = "/consumer/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id);
}

写业务类OrderHystrixController

package com.atguigu.springcloud.controller;

import com.atguigu.springcloud.service.PaymentHystrixService;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
@RestController
public class OrderHystrixController {
    @Resource
    private PaymentHystrixService paymentHystrixService;
    @GetMapping(value = "/consumer/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id){
        String result = paymentHystrixService.paymentInfo_OK(id);
        return result;
    }
    @GetMapping(value = "/consumer/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id){
        String result = paymentHystrixService.paymentInfo_TimeOut(id);
        return result;
    }
}

运行

服务降级

子项目(cloud-provider-hystrix-payment8001)的PaymentService进行修改

package com.atguigu.springcloud.service;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

@Service
public class PaymentService {

    public String paymentInfo_OK(Integer id){
        return "线程池： "+Thread.currentThread().getName()+",id"+id+"***";
    }
    @HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler",commandProperties = {
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "3000")
    })
    public String paymentInfo_Timeout(Integer id){
        int timeNumber = 5;
        try {
            TimeUnit.SECONDS.sleep(3);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "线程池： "+Thread.currentThread().getName()+",id"+id+"***,耗时"+timeNumber;
    }
    public String paymentInfo_TimeOutHandler(Integer id) {
        return "线程池： "+Thread.currentThread().getName()+"系统繁忙请稍后再试";
    }
}

在主启动类上添加注解

package com.atguigu.springcloud;

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;

@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
public class PaymentHystrixMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentHystrixMain8001.class,args);
    }
}

运行

image-20201031100915378

客户端服务降级

子项目(cloud-consumer-feign-hystrix-order80)修改配置文件application.yml

feign:
  hystrix:
    enabled: true

修改OrderHystrixController

package com.atguigu.springcloud.controller;

import com.atguigu.springcloud.service.PaymentHystrixService;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
@RestController
public class OrderHystrixController {
    @Resource
    private PaymentHystrixService paymentHystrixService;
    @GetMapping(value = "/consumer/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id){
        String result = paymentHystrixService.paymentInfo_OK(id);
        return result;
    }
    @GetMapping(value = "/consumer/payment/hystrix/timeout/{id}")
    @HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler",commandProperties = {
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "1500")
    })
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id){
        String result = paymentHystrixService.paymentInfo_TimeOut(id);
        return result;
    }
    public String paymentInfo_TimeOutHandler(Integer id) {
        return "我是80消费者，支付系统繁忙请稍后重试";
    }
}

在主启动类上加上注解

@SpringBootApplication
@EnableFeignClients
@EnableHystrix
public class OrderHystrixMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderHystrixMain80.class,args);
    }
}

运行

image-20201031102822446

全局服务降级

子项目(cloud-consumer-feign-hystrix-order80)的OrderHystrixController

package com.atguigu.springcloud.controller;

import com.atguigu.springcloud.service.PaymentHystrixService;
import com.netflix.hystrix.contrib.javanica.annotation.DefaultProperties;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
@RestController
@DefaultProperties(defaultFallback = "payment_Global_FallbackMethod")
public class OrderHystrixController {
    @Resource
    private PaymentHystrixService paymentHystrixService;
    @GetMapping(value = "/consumer/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id){
        String result = paymentHystrixService.paymentInfo_OK(id);
        return result;
    }
    @GetMapping(value = "/consumer/payment/hystrix/timeout/{id}")
    /*@HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler",commandProperties = {
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "1500")
    })*/
    @HystrixCommand
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id){
        String result = paymentHystrixService.paymentInfo_TimeOut(id);
        return result;
    }
    public String paymentInfo_TimeOutHandler(Integer id) {
        return "我是80消费者，支付系统繁忙请稍后重试";
    }
    public String payment_Global_FallbackMethod() {
        return "Gloable异常处理信息，请稍后再试";
    }
}

运行

image-20201031103943963

统配服务降级

在子项目(cloud-consumer-feign-hystrix-order80)新建一个PaymentFallbackService

package com.atguigu.springcloud.service;

import org.springframework.stereotype.Component;

@Component
public class PaymentFallbackService implements PaymentHystrixService {
    @Override
    public String paymentInfo_OK(Integer id) {
        return "paymentInfo_OK,时间超时";
    }

    @Override
    public String paymentInfo_TimeOut(Integer id) {
        return "paymentInfo_TimeOut,时间超时";
    }
}

在PaymenthystrixService类中添加注解

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT",fallback = PaymentFallbackService.class)
public interface PaymentHystrixService {
    @GetMapping(value = "/consumer/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id);
    @GetMapping(value = "/consumer/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id);
}

运行

image-20201031150521988

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原文地址：https://www.cnblogs.com/striver20/p/13966754.html