WaitGroups {.en}

WaitGroups {.zh}

::: {.en} To wait for multiple goroutines to finish, we can use a wait group. :::

::: {.zh}

要等待多个 Go 协程完成，我们可以使用 wait group。

:::

package main
import (
    "fmt"
    "sync"
    "time"
)

::: {.en} This is the function we’ll run in every goroutine. Note that a WaitGroup must be passed to functions by pointer. :::

::: {.zh}

这是我们将在每个 Go 协程中运行的函数。请注意，WaitGroup 必须通过指针传递给函数。

:::

func worker(id int, wg *sync.WaitGroup) {
    fmt.Printf("Worker %d startingn", id)

::: {.en} Sleep to simulate an expensive task. :::

::: {.zh} 等待 1s 来模拟一个耗时的任务。

:::

    time.Sleep(time.Second)
    fmt.Printf("Worker %d donen", id)

::: {.en} Notify the WaitGroup that this worker is done. :::

::: {.zh}

通知 WaitGroup 此执行已完成。

:::

    wg.Done()
}
func main() {

::: {.en} This WaitGroup is used to wait for all the goroutines launched here to finish. :::

::: {.zh}

此 WaitGroup 用于等待此处启动的所有 Go 协程完成。

:::

    var wg sync.WaitGroup

::: {.en} Launch several goroutines and increment the WaitGroup counter for each. :::

::: {.zh}

启动几个 Go 协程并为每个 Go 协程增加 WaitGroup 计数器。

:::

    for i := 1; i <= 5; i++ {
        wg.Add(1)
        go worker(i, &wg)
    }

::: {.en} Block until the WaitGroup counter goes back to 0; all the workers notified they’re done. :::

::: {.zh}

在 WaitGroup 计数器返回 0 之前阻塞；所有工作人员都通知他们已完成。

:::

    wg.Wait()
}

$ go run waitgroups.go
Worker 5 starting
Worker 3 starting
Worker 4 starting
Worker 1 starting
Worker 2 starting
Worker 4 done
Worker 1 done
Worker 2 done
Worker 5 done
Worker 3 done

::: {.en} The order of workers starting up and finishing is likely to be different for each invocation. :::

::: {.zh}

每次调用时，worker 启动和完成的顺序可能不同。

:::