只运行一次

package main

import (
    "fmt"
    "sync"
)

type Singleton struct {
}

var singleInstance *Singleton
var once sync.Once

func GetSingletionObj() *Singleton {

    once.Do(func() {
        fmt.Println("Createa Singleton")
        singleInstance = new(Singleton)
    })
    return singleInstance
}

func main() {
    var wg sync.WaitGroup
    for i := 0; i < 10; i++ {
        wg.Add(1)
        go func() {
            obj := GetSingletionObj()
            fmt.Printf("%p\n", obj)
            wg.Done()
        }()
    }
    wg.Wait()

}


// result:
Createa Singleton
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