等待多个 Backgroundworker 完成

Question

我必须处理多个大型二维数组（例如 1024 x 128），并且在我的代码的一部分中我需要转置一些（最多 12 个）。该过程需要相当长的时间，我正在尝试尽可能加快它的速度。知道 VB.NET 支持多线程，我在这里和那里阅读了不同的来源，并且可以在主子例程中提出以下代码：

RunXTransposingThreads(Arr1, Arr2, Arr3, ...)

使用 BackgroundWorkers 作为我的解决方案的一部分：

Private Sub RunXTransposingThreads(ParamArray ArraysToTranspose() As Array)
    Dim x = CInt(ArraysToTranspose.GetLength(0)) - 1
    Dim i As Integer
    For i = 0 To x
        Dim worker As New System.ComponentModel.BackgroundWorker
        AddHandler worker.DoWork, AddressOf RunOneThread
        AddHandler worker.RunWorkerCompleted, AddressOf HandleThreadCompletion
        worker.RunWorkerAsync(ArraysToTranspose(i))
    Next
End Sub

Private Sub RunOneThread(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs)
    Dim Transposed(,) As Single = Array.CreateInstance(GetType(Single), 0, 0) ' I need this to be like that in order to use other functions later
    Transposed = Transpose2dArray(CType(e.Argument, Single(,)))
    e.Result = Transposed
End Sub

Private Sub HandleThreadCompletion(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs)
    Debug.Print("Process complete")
End Sub

Function Transpose2dArray(Of Array)(ByVal inArray As Array(,)) As Array(,)

    Dim x = CInt(inArray.GetLength(1))
    Dim y = CInt(inArray.GetLength(0))
    Dim outArray(x - 1, y - 1) As Array

    For i = 0 To x - 1
        For j = 0 To y - 1
            outArray(i, j) = inArray(j, i)
        Next
    Next

    Transpose2dArray = outArray

End Function

线程似乎工作正常，因为在执行 RunXTransposingThreads 之后，我在屏幕上看到了一些 "Process complete"。问题是：如果我还没有转置数组，如何停止执行 main 中的代码？

Answer 1

您可以尝试使用build-in function复制数据

Array.Copy(inArray, outArray, CInt(inArray.GetLength(1)) * CInt(inArray.GetLength(0)))

还有一些 great example 如何使用 Parallel.ForEach。

Answer 2

正如其他人所说，BackgroundWorker 已过时。幸运的是，还有许多其他现代方法可以做到这一点。

因此，我不会向您展示可使您的代码与 BackgroundWorker 一起工作的内容。相反，我将向您展示如何使用现代方法之一的任务来完成同样的事情。希望对你有帮助。

Function RunXTransposingTasks(ParamArray ArraysToTranspose() As Array) As Array
    Dim taskList = New List(Of Task(Of Single(,))) ' our tasks returns Arrays

    For Each arr In ArraysToTranspose
        Dim r = arr
        taskList.Add(Task.Run(Function() Transpose2dArray(r)))
    Next

    Task.WhenAll(taskList) ' wait for all tasks to complete. 
    Return taskList.Select(Function(t) t.Result).ToArray()
End Function

Function Transpose2dArray(inArray As Array) As Single(,)
    Dim x = inArray.GetLength(1) - 1
    Dim y = inArray.GetLength(0) - 1
    Dim outArray(x, y) As Single

    For i = 0 To x
        For j = 0 To y
            outArray(i, j) = inArray(j, i)
        Next
    Next

    Return outArray
End Function

' Usage
' Dim result = RunXTransposingTasks(Arr1, Arr2, Arr3, ...)

等待多个 Backgroundworker 完成

Waiting for multiple Backgroundworkers to complete

vb.net

multithreading

backgroundworker

multidimensional-array