cond.go

// original: http://mattn.kaoriya.net/software/lang/go/20140625223125.htm
package main

import (
    "fmt"
    "runtime"
    "sync"
    "time"
)

func main() {
    runtime.GOMAXPROCS(runtime.NumCPU())

    l := new(sync.Mutex)
    c := sync.NewCond(l)

    // at first, creating 10 goroutine.
    for i:= 0; i < 10; i++ {
        go func(i int) {
            fmt.Printf("waiting %d\n", i)
            l.Lock()
            defer l.Unlock()
            c.Wait()
            fmt.Printf("go %d\n", i)
        }(i)
    }

    // after, process one by one
    for i := 0; i < 10; i++ {
        time.Sleep(1 * time.Second)
        // Signal dispatch each routines. 
        c.Signal()
    }
    time.Sleep(1 * time.Second)
}