Goroutine 并发

示范 1 ：main goroutin同步阻塞等待 3 个 goroutine 结束：

func main() {
    var wg sync.WaitGroup
    wg.Add(3)
    go doSomething(1, &wg)
    go doSomething(2, &wg)
    go doSomething(3, &wg)
    wg.Wait()
}
func doSomething(id int, wg *sync.WaitGroup) {
    defer wg.Done()
    log.Printf("before do job:(%d) \n", id)
    time.Sleep(3 * time.Second)
    log.Printf("after do job:(%d) \n", id)
}

范例 2：专用于Go通道的Select：

func main() {
    chStr := make(chan string)
    chInt := make(chan int)
    go strWorker(chStr)
    go intWorker(chInt)
    for {
        select {
        case <-chStr:
            fmt.Println("get value from strWorker")
        case <-chInt:
            fmt.Println("get value from intWorker")
        }
        fmt.Println("one worker catched")
    }
}
func strWorker(ch chan string) {
    for i := 0; i < 10; i++ {
        time.Sleep(3 * time.Second)
        ch <- "str" + strconv.Itoa(i)
    }
}
func intWorker(ch chan int) {
    time.Sleep(5 * time.Second)
    ch <- 1
}

定时器与Goroutine:

tick := time.Tick(3 * time.Second)
boom := time.After(10 * time.Second)
for {
    select {
    case <-tick:
        fmt.Println("tick.")
    case <-boom:
        fmt.Println("BOOM!")
        return
    default:
        fmt.Println("    .")
        time.Sleep(time.Second)
    }
}