This is interesting and I still don't get why it's not working. I modified the code a bit and expected it to immediately break out of select but it still waits for http calls to finish
https://play.golang.org/p/z1mmqpQtOre package main import ( "errors" "fmt" "net/http" "net/http/httptest" "time" ) func main() { ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { time.Sleep(1 * time.Second) w.WriteHeader(http.StatusOK) })) defer ts.Close() req, _ := http.NewRequest(http.MethodGet, ts.URL, nil) f := func(r *http.Request, n int) error { fmt.Println("Making the http call ", n) _, err := http.DefaultClient.Do(r) return err } ch := make(chan error, 1) timeout := 1 * time.Millisecond select { case ch <- errors.New("immediate timeout"): case ch <- f(req, 1): case ch <- f(req, 2): case <-time.After(timeout): fmt.Println("Timeout being called") ch <- errors.New("timeout") } err1 := <-ch fmt.Println("Received first error", err1) close(ch) // Output: // Making the http call 1 // Making the http call 2 // Received first error immediate timeout } On Monday, May 21, 2018 at 10:25:08 PM UTC-7, Burak Serdar wrote: > > On Mon, May 21, 2018 at 12:13 PM, <gopher...@gmail.com <javascript:>> > wrote: > > timeout := 1 * time.Millisecond > > select { > > case ch <-f(req): > > case <-time.After(timeout): > > ch <- errors.New("timeout") > > } > > The instant 'select' is evaluated, ch is writable. Also time.After() > is called, and returns a channel that will be ready to be read in a > millisecond, i.e. not readable immediately. So it'll write to ch, and > will never timeout. > > To do what you described, you need to run the request piece in a > goroutine, and write the result to a channel: > > go func() { > _,err:=http.DefaultClient.Do(...) > ch<-err > }() > > Then, wait for the error to arrive on ch, or timeout: > > select { > case err:=<-ch: > case <-time.After(timeout): > } > > > > err:= <-ch > > close(ch) > > fmt.Println(err) // outputs <nil>, not timeout > > // Output: > > // timeout > > } > > > > > > -- > > You received this message because you are subscribed to the Google > Groups > > "golang-nuts" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to golang-nuts...@googlegroups.com <javascript:>. > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
