Golang使用断路器hystrix

断路器的相关原理可参考：https://skaygo.blog.youkuaiyun.com/article/details/110442898

hystrix-go的源码地址：https://github.com/afex/hystrix-go

下载：go get github.com/afex/hystrix-go/hystrix

 

开启一个简单的http服务svc

请求 /hello 会返回 hello,world

相关代码如下（svc.go）：

package main

import (
	"io"
	"log"
	"net/http"
)

func main() {
	http.HandleFunc("/hello",helloServer)
	log.Fatal(http.ListenAndServe(":18080",nil))
}


func helloServer(w http.ResponseWriter, req *http.Request) {
	log.Println("request remote addr",req.RemoteAddr)
	io.WriteString(w, "hello,world")
}

 

 

go run svc.go

运行之后浏览器中请求

 

http客户端client使用断路器hystrix

相关代码如下(client.go)：

package main

import (
	"log"
	"time"
	"errors"
	"io/ioutil"
	"net/http"
	
	"github.com/afex/hystrix-go/hystrix"
)

func main() {
	httpURL := "http://localhost:18080/hello"

	//初始化hystrix配置
	hystrix.ConfigureCommand("svc1", hystrix.CommandConfig{
		MaxConcurrentRequests : 5,  //设置请求的并发数量
		RequestVolumeThreshold : 4,  //配置断路器断开需要的最少请求失败数量
	})


	for i := 0 ; i < 10 ; i++ {
		for j := 0 ; j< 10 ; j++ {
			go func() {
				req,err := httpDo(httpURL)
				if err != nil {
					log.Println("http request error :",err.Error())
				}else {
					log.Println("http request success:",string(req))
				}
			}()
		}
		time.Sleep(time.Second*5)
	}

}

//http请求
func httpDo(url string) (respBytes []byte, err error) {
	var resp *http.Response
	err = hystrix.Do("svc1",func() error {
		resp,err = http.Get(url)
		if err != nil {
			return err
		}
		respBytes,err = ioutil.ReadAll(resp.Body)
		if err !=nil {
			return err
		}

		return nil
	}, func(error) error {
		return errors.New("http request error")
	})

	return
}

 

go run client.go

可以看到断路器在这10次请求中反复被打开

 

思考：

1.可以将MaxConcurrentRequests改成7，观察断路器是否会被打开，

2. 将MaxConcurrentRequests的值改为10，在client运行过程中关闭svc，过一会儿再打开svc，观察情况