Golang concurrent cache breakdown or merge request

package main

import (
	"golang.org/x/sync/singleflight"
	"log"
	"time"
)

func main() {
    
	var singleSetCache singleflight.Group

	getAndSetCache := func(requestID int, cacheKey string) (string, error) {
    
		value, _, _ := singleSetCache.Do(cacheKey, func() (ret interface{
    }, err error) {
     //do Input key, You can use cached key, So the same cache , Only one program will read DB
			log.Printf("requestid Do it once  %v ", requestID)
			return "VALUE", nil
		})
		return value.(string), nil
	}

	cacheKey := "cacheKey"
	for i := 1; i < 10; i++ {
     // Simulate multiple concurrent requests 
		go func(requestID int) {
    
			value, _ := getAndSetCache(requestID, cacheKey)
			//_ = value
			log.Printf("requestID %v get  value : %v", requestID, value)
		}(i)
	}
	time.Sleep(20 * time.Second)
}