为什么fetch一个不存在的网址，程序不会timeout

```package main

import ( "bufio" "fmt" "io" "io/ioutil" "net/http" "os" "time" )

func main() { start := time.Now() ch := make(chan string) urls := loadUrls("urls.txt") for _, url := range urls { go fetch(url, ch) } for range urls { fmt.Println(<-ch) } fmt.Printf("%.3fs elapsed\n", time.Since(start).Seconds()) }

func loadUrls(filename string) []string { f, err := os.Open("urls.txt") if err != nil { fmt.Fprintln(os.Stderr, err) os.Exit(1) } input := bufio.NewScanner(f) urllist := make([]string, 0, 16) for input.Scan() { urllist = append(urllist, "http://"+input.Text()) } f.Close() return urllist }

func fetch(url string, ch chan<- string) { t := time.NewTimer(10 * time.Second) select { case <-t.C: ch <- fmt.Sprint("time out:", url) default: start := time.Now() resp, err := http.Get(url) if err != nil { ch <- fmt.Sprint(err) return } nbytes, err := io.Copy(ioutil.Discard, resp.Body) resp.Body.Close() if err != nil { ch <- fmt.Sprintf("while reading %s: %v", url, err) return } secs := time.Since(start).Seconds() ch <- fmt.Sprintf("%.3fs %8d %s", secs, nbytes, url) } } ```