// +build ignore,OMIT package main import ( "fmt" "sync" ) func main() { const workers = 100 // what if we have 1, 2, 25? var wg sync.WaitGroup wg.Add(workers) m := map[int]int{} for i := 1; i <= workers; i++ { go func(i int) { for j := 0; j < i; j++ { m[i]++ // HL } wg.Done() }(i) } wg.Wait() fmt.Println(m) }