Running a simple server, but the counter seems to go up by 3, why?

I have this little server here. The intent is that if I visit localhost:8000/* it should increase counter by 1, and if I go to localhost:8000/count, it should show me the current number of counter.

A weird thing happening is that it seems like every time I visit localhost:8000, the counter goes up by 3. So I'd go to localhost:8000/count and the counter would be at 3, and then I visit localhost:8000, and then localhost:8000/count again, counter would now be at 6. Why does that happen? Is there something weird with net/http?

Also, why is it that when I refresh localhost:8000/count, the count goes up 1 by 1? The counter func doesn't increment count, yet count still goes up - why is that? Does handler get added to the localhost:8000/count route as well?

package main

import (
        "fmt"
        "log"
        "net/http"
        "sync"
)

var mu sync.Mutex
var count int

func main() {
        http.HandleFunc("/", handler)
        http.HandleFunc("/count", counter)
        log.Fatal(http.ListenAndServe("localhost:8000", nil))
}

// handler echoes the Path component of the requested URL.
func handler(w http.ResponseWriter, r *http.Request) {
        mu.Lock()
        count++
        mu.Unlock()
        fmt.Fprintf(w, "URL.Path = %q\n", r.URL.Path)
}

// counter echoes the number of calls so far.
func counter(w http.ResponseWriter, r *http.Request) {
        mu.Lock()
        fmt.Fprintf(w, "Count %d\n", count)
        mu.Unlock()
}

The extra requests are your browser trying to access /favicon.ico

You can see this, for example, if you print the http.Request to stdout in your handler funcs.

The issue is that your handler is serving extra static content like favicon and such. If you log the request, you'll see your browser is probably also requesting
/favicon.ico, which is being passed to that same handler.

To serve static content one way is to create your own ServeMux:

package main

import (
    "fmt"
    "net/http"
    "strings"
)   

var chttp = http.NewServeMux()

func main() {

    chttp.Handle("/", http.FileServer(http.Dir("./")))

    http.HandleFunc("/", HomeHandler) // homepage
    http.ListenAndServe(":8080", nil)
}   

func HomeHandler(w http.ResponseWriter, r *http.Request) {

    if (strings.Contains(r.URL.Path, ".")) {
        chttp.ServeHTTP(w, r)
    } else {
        fmt.Fprintf(w, "HomeHandler")
    }   
} 

https://stackoverflow.com/questions/14086063/serve-homepage-and-static-content-from-root