profiler

package main

import (
    "flag"
    "time"
    "os"
    "log"
  "fmt"
    "net/http"
    "runtime"
    "encoding/csv"
)

var (
    addr         =  flag.String("addr", "localhost", "http service address")
    port         =  flag.String("port", "9082", "http service port")
)

func serveHome(m *runtime.MemStats) http.HandlerFunc {
    fn := func (w http.ResponseWriter, r *http.Request) {
    log.Println(r.URL)
    runtime.ReadMemStats(m)
    w.WriteHeader(200)
    w.Write([]byte("Server Stats\n"))

        t := time.Now()
    w.Write([]byte(fmt.Sprintf("Timestamp: %d\n", t.Unix())))
    w.Write([]byte(fmt.Sprintf("Alloc usage: %d KB\n", m.Alloc/1e3)))
    w.Write([]byte(fmt.Sprintf("TotalAlloc usage: %d KB\n", m.TotalAlloc/1e3)))
    w.Write([]byte(fmt.Sprintf("Sys usage: %d KB\n", m.Sys/1e3)))
    w.Write([]byte(fmt.Sprintf("Goroutine count: %d\n", runtime.NumGoroutine())))
  }
    return http.HandlerFunc(fn)
}

func main() {
    flag.Parse()
    var m   runtime.MemStats

    // monitoring
    file, errf := os.Create("stat.txt")
    if errf != nil {
        log.Fatal(errf)
    }
    defer file.Close()
    writer := csv.NewWriter(file)
    defer writer.Flush()

    errw := writer.Write([]string{"TIME", "ALLOC", "SYS"})
    if errw != nil {
        log.Fatal(errw)
    }

    ticker := time.NewTicker(10 * time.Second)
    quit := make(chan struct{})
    defer close(quit)
    go func(m *runtime.MemStats) {
        for {
       select {
        case <- ticker.C:
                    runtime.ReadMemStats(m)
                    errw = writer.Write([]string{fmt.Sprintf("%d", time.Now().Unix()), string(fmt.Sprintf("%d", m.Alloc)), string(fmt.Sprintf("%d", m.Sys))})
                    if errw != nil {
                        log.Fatal(errw)
                    }
                    writer.Flush()
        case <- quit:
            ticker.Stop()
            return
        }
    }
    }(&m)

    http.HandleFunc("/", serveHome(&m))
    err := http.ListenAndServe(*addr + ":" + *port, nil)
    if err != nil {
        log.Fatal("ListenAndServe: ", err)
    }

}