<span style="font-size:18px;color:#3333ff;">package main import ( "golang.org/x/net/context" "log" "math/rand" "time" ) func test(is_first *bool, prev_map *map[string]string) { rand.Seed(int64(time.Now().Nanosecond())) ch := make(chan bool) ctx, _ := context.WithTimeout(context.Background(), 50*time.Millisecond) go func() { if *is_first { (*prev_map)["a"] = "1" } else { (*prev_map)["a"] = "2" } time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond) ch <- true }() select { case <-ch: *is_first = false (*prev_map)["b"] = "fast" return case <-ctx.Done(): *is_first = true (*prev_map)["b"] = "slow" return } } func main() { is_first := true prev_map := make(map[string]string) for { test(&is_first, &prev_map) time.Sleep(time.Second) log.Println(prev_map, is_first) } }</span>
<span style="font-size:18px;color:#3333ff;">[work@localhost test]$ go run main.go 2016/08/18 23:22:26 map[a:1 b:fast] false 2016/08/18 23:22:27 map[a:2 b:slow] true 2016/08/18 23:22:28 map[a:1 b:slow] true 2016/08/18 23:22:29 map[a:1 b:fast] false 2016/08/18 23:22:30 map[b:fast a:2] false 2016/08/18 23:22:31 map[b:slow a:2] true 2016/08/18 23:22:32 map[a:1 b:fast] false 2016/08/18 23:22:33 map[a:2 b:slow] true 2016/08/18 23:22:34 map[a:1 b:slow] true 2016/08/18 23:22:35 map[a:1 b:slow] true 2016/08/18 23:22:36 map[a:1 b:slow] true ^Csignal: interrupt</span>