closeStartIdx := loopCount / 2 // close the database at the middle of the execution
	var lastRunIndex int
	var closeFinishedAt int64

	wg.Add(1)
	go func(id uint) {
		defer wg.Done()
		defer close(closeValid)
		for lastRunIndex = 1; lastRunIndex <= loopCount; lastRunIndex++ {
			if lastRunIndex == closeStartIdx {
				closeValid <- struct{}{}
			}
			var tmp User
			now := time.Now().UnixNano()