挑战Go方式“不要通过共享内存来通信，而是通过通信来共享内存。”

Question

我试图遵循 Go 的“不要通过共享内存来通信，而是通过通信来共享内存”的方式，使用通道来异步地传达要完成的任务，并发送回处理任务的结果。

为了简单起见，我已将通道类型更改为 int，而不是它们真正的结构。并用

time.Sleep()

代替了漫长的处理。

如何在发回所有任务结果后关闭

producedResults

，以便此代码不会卡在最后

for

？

    quantityOfTasks:= 100
    quantityOfWorkers:= 60
    remainingTasks := make(chan int)
    producedResults := make(chan int)

    // produce tasks
    go func() {
        for i := 0; i < quantityOfTasks; i++ {
            remainingTasks <- 1
        }
        close(remainingTasks)
    }()

    // produce workers
    for i := 0; i < quantityOfWorkers; i++ {
        go func() {
            for taskSize := range remainingTasks {
                // simulate a long task
                time.Sleep(time.Second * time.Duration(taskSize))
                // return the result of the long task
                producedResults <- taskSize
            }
        }()
    }

    // read the results of the tasks and agregate them
    executedTasks := 0
    for resultOfTheTask := range producedResults { //this loop will never finish because producedResults never gets closed
        // consolidate the results of the tasks
        executedTasks += resultOfTheTask
    }

Answer 1

您希望在写入该通道的所有 goroutine 返回后关闭该通道。您可以为此使用 WaitGroup：

wg:=sync.WaitGroup{}

for i := 0; i < quantityOfWorkers; i++ {
        wg.Add(1)
        go func() {
            defer wg.Done()
            for taskSize := range remainingTasks {
                //simulate a long task
                time.Sleep(time.Second * time.Duration(taskSize))
                //return the result of the long task
                producedResults <- taskSize
            }
        }()
}

go func() {
  wg.Wait()
  close(producedResults)
}()

Answer 2

等待worker完成后关闭通道。

var wg sync.WaitGroup
wg.Add(quantityOfWorkers)
go func() {
    wg.Wait()
    close(producedResults)
}()

for i := 0; i < quantityOfWorkers; i++ {
    go func() {
        defer wg.Done()
    ...

https://go.dev/play/p/kdgemc5Unsy