var ok, errs int
	var wg sync.WaitGroup
	var mu sync.Mutex
	wg.Add(n)
	for i := 0; i < n; i++ {
		go func() {
			defer wg.Done()
			// Sync start.
			<-start
			if err := obj.MakeBucket(GlobalContext, bucketName1, MakeBucketOptions{}); err != nil {
				if _, ok := err.(BucketExists); !ok {
					t.Logf("unexpected error: %T: %v", err, err)
					return
				}
				mu.Lock()
				errs++
				mu.Unlock()