0-pause.go

package main

import (
        "log"
        "time"
)

func main() {
        ch := make(chan int)
        go func() {
                for {
                        select {
                        case ch <- func() int {
                                log.Printf("reserved")
                                return 1
                        }():
                        default:
                                log.Printf("waited")
                                time.Sleep(1 * time.Second)
                        }
                }
        }()
        time.Sleep(5 * time.Second)
        log.Printf("got %d", <-ch)
}

1-output

2013/07/11 15:53:25 reserved
2013/07/11 15:53:25 waited
2013/07/11 15:53:26 reserved
2013/07/11 15:53:26 waited
2013/07/11 15:53:27 reserved
2013/07/11 15:53:27 waited
2013/07/11 15:53:28 reserved
2013/07/11 15:53:28 waited
2013/07/11 15:53:29 reserved
2013/07/11 15:53:29 waited
2013/07/11 15:53:30 reserved
2013/07/11 15:53:30 reserved
2013/07/11 15:53:30 waited
2013/07/11 15:53:30 got 1

2-desired

2013/07/11 15:53:25 waited
2013/07/11 15:53:26 waited
2013/07/11 15:53:27 waited
2013/07/11 15:53:28 waited
2013/07/11 15:53:29 waited
2013/07/11 15:53:30 reserved
2013/07/11 15:53:30 got 1