如何在同一台服务器上休息api和websocket？

I have a restful api. I integrate a route to opening a websocket when the user receives a new notification or message. Once socket is open, API doesn't work, it no longer receives any request.

this is my main func

func initWebSocket(){
    http.HandleFunc("/websocket", websocketHandler)
}
func main() {

    // init api's routes
    initRoutes()

    //init rethinkDB
    api.InitRethinkDB()

    //init opening websocket's route.
    initWebSocket()

    config := swagger.Config{
        WebServices:    restful.RegisteredWebServices(), // you control what services are visible
        WebServicesUrl: "http://localhost:9000",
        ApiPath:        "/apidocs.json",

        // Optionally, specifiy where the UI is located
        SwaggerPath:     "/apidocs/",
        SwaggerFilePath: "swagger-ui/dist"}

    swagger.InstallSwaggerService(config)

    http.ListenAndServe(":9000", nil)

}

websocker handler :

func handleChangeNotification(socket *websocket.Conn, userID string, err chan string){
    res, errr := r.Table("Notifications").
              Filter(r.Row.Field("UserId").
              Eq(userID)).
              Changes().
              Run(api.Sess)

    var value HandleChange
    if errr != nil {
        err <- errr.Error()
    }
    for res.Next(&value){
        var notif Notification
        mapstructure.Decode(value.NewVal, &notif)
        errr := socket.WriteJSON(notif)
        if errr != nil {
            err <- errr.Error()
        }
    }
}

func websocketHandler(w http.ResponseWriter, r *http.Request){
    socket, _ := upgrader.Upgrade(w, r, nil)
    err := make(chan string)
    run := false

    go func(){
        for {
            if run == false {
                go handleChangeNotification(socket, id, err)
                run = true        
            }
            if len(err) > 0 {
                break
            }
        }
        socket.Close()
    }()
}

How can I do to run the websocket and API on the same server?