【說一說】Hystrix停更不停用，慢慢進入維護時代

前言

最近在開發微服務，使用到了Hystrix組件，我們知道hystrix組件目前已經停止更新了，但是項目中使用的熱度不減少。下面進行深刨細挖，呈現他的魅力

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Hystrix

它是一個用於處理分佈式系統的延遲和容錯的開源庫,在分佈式系統裏，許多依賴不可避免的會調用失敗，比如超時，異常等，Hystrix能夠保證在一個依賴出問題的情況下，不會導致整體服務失敗，避免級聯故障，以提高分佈式系統的彈性。
“斷路器”本身是一種開關裝置，當某個服務單元發生故障之後，通過斷路器的故障監控（類似熔斷保險絲），向調用方返回一個符合預期的、可處理的備選響應（FallBack），而不是長時間的等待或者拋出調用方無法處理的異常，這樣保證了服務調用方的線程不會被長時間，不必要地佔用，從而避免了故障在分佈式系統中的蔓延，乃至雪崩。

• 維護公告：
  
  重要的概念：
• 服務降級
  哪些情況會出現降級呢：程序運行時異常、超時、服務熔斷觸發服務降級、線程池/信號量打滿也會導致服務降級
• 服務熔斷
• 服務限流

demo

• 構建Module
  
  
  
  

• 修改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>com.zcw.springcloud2020508</artifactId>
        <groupId>com.zcw</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><!--引入自己定義的api通用包，可以使用Payment支付Entity-->
            <groupId>com.zcw</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>

• 創建YML

server:
  port: 8001

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

eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      defaultZone:  http://server2:7008/eureka/,http://server1:7001/eureka/

• 修改啓動類

package com.zcw.springcloud;

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

/**
 * @ClassName : PaymentHystrixApplication
 * @Description :
 * @Author : Zhaocunwei
 * @Date: 2020-05-19 15:45
 */
@SpringBootApplication
@EnableEurekaClient
public class PaymentHystrixApplication {
    public static void main(String[] args) {
        SpringApplication.run(PaymentHystrixApplication.class,args);
    }
}

• 編寫業務類

package com.zcw.springcloud.service;

import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

/**
 * @ClassName : PaymentService
 * @Description :
 * @Author : Zhaocunwei
 * @Date: 2020-05-19 15:48
 */
@Service
public class PaymentService {

    public String paymentInfo_OK(Integer id){
        return "線程池： "+ Thread.currentThread().getName()+"         paymentInfo_OK，id:"+id+"\t"+"O(∩_∩)O哈哈~";
    }

    public String paymentInfo_TimeOut(Integer  id){
        try {
            TimeUnit.SECONDS.sleep(3);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return " 線程池：   "+Thread.currentThread().getName()+" paymentInfo_TimeOut,id:"+id+"\t"+"O(∩_∩)O哈哈~"+ "耗時3秒鐘";
    }
}

• 編寫controller

package com.zcw.springcloud.controller;

import com.zcw.springcloud.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;

/**
 * @ClassName : PaymentController
 * @Description :
 * @Author : Zhaocunwei
 * @Date: 2020-05-19 15:58
 */
@RestController
@Slf4j
public class PaymentController {
    @Resource
    private PaymentService paymentService;

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

    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id){
        String result = paymentService.paymentInfo_OK(id);
        log.info("************result======{}",result);
        return result;
    }
    @GetMapping("/payment/hystrix/timeout/{id}")
    public String payment_Timeout(@PathVariable("id")Integer id){
        String result = paymentService.paymentInfo_TimeOut(id);
        log.info("******result:"+result);
        return result;
    }
}

• 測試