dnsbench

dnsbench.go

package main

import (
        "context"
        "flag"
        "fmt"
        "net"
        "time"
)

var (
        concurrency = flag.Int("c", 100, "concurrency requests")
        totalReq    = flag.Int("n", 10000, "total requests")
        slowSec     = flag.Float64("s", 5, "response larger than this value, considered as slow")
        host        = flag.String("d", "google.com", "host to query")
)

func main() {
        flag.Parse()

        slowCount := 0
        sem := make(chan bool, *concurrency)
        for i := 0; i < *totalReq; i++ {
                sem <- true
                go func() {
                        defer func() { <-sem }()
                        resolver := &net.Resolver{}
                        t := time.Now()
                        _, err := resolver.LookupIPAddr(context.Background(), *host)
                        if err != err {
                                fmt.Println(err)
                        }
                        cost := time.Since(t).Seconds()
                        if cost >= *slowSec {
                                slowCount += 1
                                fmt.Println("slow resp:", cost)
                        }
                }()
        }
        for i := 0; i < cap(sem); i++ {
                sem <- true
        }
        fmt.Println("slowCount:", slowCount)
}