testdrainup.go

package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"sync"
	"time"

	"github.com/gin-gonic/gin"
)

const (
	numRoutine = 100
	numRequest = 100
)

func startServer() {
	r := gin.New()
	r.GET("/ping", func(c *gin.Context) {
		c.JSON(200, gin.H{
			"message": "pong",
			"ab":      "cd",
		})
	})
	go r.Run() // listen and serve on 0.0.0.0:8080
}

func doGetWithDrainup() {
	start := time.Now()

	// multiple call
	var wg sync.WaitGroup
	for i := 0; i < numRoutine; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()

			client := http.DefaultClient
			for j := 0; j < numRequest; j++ {
				resp, err := client.Get("http://localhost:8080/ping")
				if err != nil {
					return
				}
				io.CopyN(ioutil.Discard, resp.Body, 512)
				resp.Body.Close()
			}
		}()
	}
	wg.Wait()

	fmt.Printf("With drainup: %.3f\n", time.Since(start).Seconds())
}

func doGetWithoutDrainup() {
	start := time.Now()

	// multiple call
	var wg sync.WaitGroup
	for i := 0; i < numRoutine; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()

			client := http.DefaultClient
			for j := 0; j < numRequest; j++ {
				resp, err := client.Get("http://localhost:8080/ping")
				if err != nil {
					return
				}
				resp.Body.Close()
			}
		}()
	}
	wg.Wait()

	fmt.Printf("Without drainup: %.3f\n", time.Since(start).Seconds())
}

func main() {
	startServer()

	// wait server start
	time.Sleep(time.Second)
	doGetWithDrainup()

	time.Sleep(time.Second)
	doGetWithoutDrainup()
}