《SpringCloud专题16》-Hystrix熔断器

1.概述

1.1.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10个依赖关系,每个依赖关系在某些时候将不可避免地失败

1.2.是什么

1.3.能干嘛

服务降级
服务熔断
接近实时的监控      

1.4.官网资料

​​https://github.com/Netflix/hystrix/wiki​​​

1.5.官宣,停更进维

​​https://github.com/Netflix/hystrix​​​

被动修复bugs
不再接受合并请求
不再发布新版本      

2.HyStrix重要概念

2.1.服务降级

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

2.2.哪些情况会发出降级

程序运行异常
超时
服务熔断触发服务降级
线程池/信号量也会导致服务降级      

2.3.服务熔断

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

就是保险丝

服务的降级->进而熔断->恢复调用链路      

2.4.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

3.hystrix案例

3.1.构建

新建cloud-provider-hystrix-payment8001

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>springcloud2020</artifactId>
        <groupId>com.itxiongmao.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>

        <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-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

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


        <dependency>
            <groupId>com.itxiongmao.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>1.0-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>

    </dependencies>


</project>      

YML

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,http://eureka7002.com:7002/eureka      

主启动

package com.itxiongmao;

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

/**
 * @BelongsProject: springcloud2020
 * @BelongsPackage: com.itxiongmao
 * @CreateTime: 2020-11-22 12:37
 * @Description: TODO
 */
@SpringBootApplication
@EnableEurekaClient
public class PaymentHystrixMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentHystrixMain8001.class, args);
    }
}      

业务类

service

package com.itxiongmao.service;

/**
 * @BelongsProject: springcloud2020
 * @BelongsPackage: com.itxiongmao.service
 * @CreateTime: 2020-11-22 12:39
 * @Description: TODO
 */
public interface PaymentService {

    String getPaymentInfo_OK(Integer id);
    
   String paymentInfo_TimeOut(Integer id);
}      

package com.itxiongmao.service.impl;

import com.itxiongmao.service.PaymentService;
import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

/**
 * @BelongsProject: springcloud2020
 * @BelongsPackage: com.itxiongmao.service.impl
 * @CreateTime: 2020-11-22 12:39
 * @Description: TODO
 */
@Service
public class PaymentServiceImpl implements PaymentService {

    /*
     * 正常访问
     * @param id
     * @return
     */
    @Override
    public String getPaymentInfo_OK(Integer id) {
        return "线程池:" + Thread.currentThread().getName() + " paymentInfo_OK,id:" + id + "\t" + "O(∩_∩)O哈哈~";
    }

    /**
     * 超时访问
     *
     * @param id
     * @return
     */
    @Override
    public String paymentInfo_TimeOut(Integer id) {
        int timeNumber = 3;
        try {
            // 暂停3秒钟
            TimeUnit.SECONDS.sleep(timeNumber);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "线程池:" + Thread.currentThread().getName() + " paymentInfo_TimeOut,id:" + id + "\t" +
                "O(∩_∩)O哈哈~  耗时(秒)" + timeNumber;
    }
}      

PaymentController

package com.itxiongmao.controller;


import com.itxiongmao.service.PaymentService;
import lombok.extern.slf4j.Slf4j;
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;
import java.util.concurrent.TimeUnit;

@RestController
@Slf4j
public class PaymentController {

    @Resource
    private PaymentService paymentService;

    @Value("${server.port}")
    private String servicePort;

    /**
     * 正常访问
     *
     * @param id
     * @return
     */
    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id) {
        String result = paymentService.getPaymentInfo_OK(id);
        log.info("*****result:" + result);
        return result;
    }

    /**
     * 超时访问
     *
     * @param id
     * @return
     */
    @GetMapping("/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id) {
        String result = paymentService.paymentInfo_TimeOut(id);
        log.info("*****result:" + result);
        return result;

    }
}      

3.2.正常测试

启动eureka7001
启动eureka-provider-hystrix-payment8001      

访问

success的方法

​​​ http://localhost:8001/payment/hystrix/ok/31​​

每次调用耗费5秒钟

​​​ http://localhost:8001/payment/hystrix/timeout/31​​