package main

import (

    "fmt"

    "sync"

)

type Singleton struct{}

var singleton *Singleton

var once sync.Once

func GetSingletonObj() *Singleton {

    once.Do(func() {

        fmt.Println("Create Obj")

        singleton = new(Singleton)

    })

    return singleton

}

func main() {

    var wg sync.WaitGroup

    for i := 0; i < 5; i++ {

        wg.Add(1)

        go func() {

            obj := GetSingletonObj()

            fmt.Printf("%p\n", obj)

            wg.Done()

        }()

    }

    wg.Wait()

}