I have this following program where I am trying to store some final results based on each go-routine and the trick I am using to not have race condition is by designating a particular array index for each go-routine.

func TestHHH(t *testing.T) {
    arr := []int{1, 2, 3, 4, 5}
    result := make([]int, len(arr))

    wg := sync.WaitGroup{}
    for i, v := range arr {
       index := i
       val := v
       go func() {
          wg.Add(1)
          defer wg.Done()
          result[index] = val
       }()
    }
    wg.Wait()
    fmt.Println(result)
}

I understand I can use mutexes or channels to fix the race condition, but I am just wondering why the above code has a race condition. I wanted the go-routines to be faster instead of waiting for mutex locks or waiting for channel operations.

Isn’t it each go-routine pointing to different indexes that are mutually exclusive?