Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

1.7.3

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"

What did you do?

fileSink, err := os.OpenFile("./text.txt", os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0655)
	if err != nil {
		return
	}

	csv := csv.NewWriter(fileSink)
	csv.Write([]string{"haha"})
	csv.Flush()
	//fileSink.Sync()
	time.Sleep(time.Minute)

After csv.Flush, the file doesn't Sync.

Shouldn't sync after csv.Flush?