如何等待 go-routines 完成？

Question

下面是场景：inputCh := g(abc) // return <- chan []stringslice := make([]map[string][]string, 0)m := sync.Mutex{}for whatever := range inputCh {    go func(whatever []string) {        matches := f(xyz, whatever) // returns map[string][]string        m.Lock()        slice = append(slice, matches)        m.Unlock()    }(whatever)}z := merge(slice...)我们不知道的地方，何时inputCh关闭（close(inputCh)）merge(slice...)我们只需要在所有 go-routines 完成和更新后调用slice不确定，如果sync.WaitGroup可以使用。如何确保只有在所有 go-routines 更新merge(slice...)后才被调用？slice

Answer 1

使用sync.WaitGroup并检查通道何时关闭

var wg sync.WaitGroup

for {

    whatever, ok := <-inputCh

    if !ok { // check inputCh is close

        break

    }

    // add delta

    wg.Add(1)

    go func(whatever []string) {

        matches := f(xyz, whatever)

        m.Lock()

        slice = append(slice, matches)

        m.Unlock()

        // goroutine is done

        wg.Done()

    }(whatever)

}

// waits until all the goroutines call "wg.Done()"

wg.Wait()

Answer 2

您可以使用sync.WaitGroup.

// create a work group

var wg sync.WaitGroup

// add delta

wg.Add(len(inputCh))

slice := make([]map[string][]string, 0)

m := sync.Mutex{}

for whatever := range inputCh {

    go func(whatever []string) {

        matches := f(xyz, whatever) // returns map[string][]string

        m.Lock()

        slice = append(slice, matches)

        m.Unlock()

        // signal work group that the routine is done

        wg.Done()

    }(whatever)

}

// waits until all the go routines call wg.Done()

wg.Wait()