VB.net多線程循環，並行線程

Question

我有一個簡單的形式與2個RichTextBoxes和1個按鈕，代碼抓取從RichTextBox1的URL地址和短語標題字段的頁面使用正則表達式並將其附加到RichTextBox2。我想以這樣的方式對所有東西進行多線程處理，以避免跳過所有url，並且可以設置線程數量（根據系統免費資源）。例如，假設10個線程並行運行。我搜索了一切，我設法做的最好的事情是在後臺工作中運行所有內容，並在工作時防止GUI凍結。短代碼示例將有很大的幫助，我是VB.net的初學者。

Public Class Form1 

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load 

    End Sub 

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
     For i = 0 To RichTextBox1.Lines.Length - 1 
      If RichTextBox1.Lines(i).Contains("http://") Then 
       Dim html As String = New System.Net.WebClient() _ 
        .DownloadString(RichTextBox1.Lines(i)) 
       Dim pattern As String = "(?<=\<title\>)([^<]+?)(?=\</title\>)" 
       Dim match As System.Text.RegularExpressions.Match = _ 
        System.Text.RegularExpressions.Regex.Match(html, pattern) 
       Dim title As String = match.Value 
       RichTextBox2.AppendText(title & vbCrLf) 
      End If 
     Next 
    End Sub 
End Class 

更新後的代碼（投擲「索引數組的範圍之外」的錯誤。）

Imports System 
Imports System.Threading 

Public Class Form1 
    Public Sub test(ByVal val1 As String, ByVal val2 As String) 
     Dim zrow As String 
     zrow = RichTextBox1.Lines(val1) 

     If zrow.Contains("http://") Then 
      Dim html As String = New System.Net.WebClient().DownloadString(zrow) 
      Dim pattern As String = "(?<=\<title\>)([^<]+?)(?=\</title\>)" 
      Dim match As System.Text.RegularExpressions.Match = System.Text.RegularExpressions.Regex.Match(html, pattern) 
      Dim title As String = match.Value 
      RichTextBox2.AppendText(val2 & title & vbCrLf) 
     End If 
    End Sub 

    Public Sub lastfor(ByVal number) 
     Dim start As Integer = number - 100 

     For x = start To number - 1 
      Try 
       test(x, x) 
       RichTextBox2.AppendText(x & RichTextBox1.Lines(x).Trim & vbCrLf) 
      Catch ex As Exception 
       'MsgBox(ex.Message) 
       RichTextBox3.AppendText(ex.Message & vbCrLf & vbCrLf) 
      End Try 
     Next 

    End Sub 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load 
     Control.CheckForIllegalCrossThreadCalls = False 
    End Sub 

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
     Dim TotalLines As String = RichTextBox1.Lines.Length - 1 
     Dim TotalThreads As Integer = 10 
     Dim LinesPerThread As Integer = TotalLines/TotalThreads 
     Dim increment As String = LinesPerThread 

     Dim zdata(TotalThreads) As String 
     For i = 0 To TotalThreads - 1 
      zdata(i) = increment 
      increment = increment + LinesPerThread 
     Next 





     Dim lst As New List(Of Threading.Thread) 
     For Each bump As String In zdata 
      Dim t As New Threading.Thread(Function(l As String) 
               'Do something with l 
               'Update GUI like this: 
               If bump = String.Empty Or bump Is Nothing Then 
               Else 

                lastfor(l) 
                'MsgBox(l) 
               End If 
              End Function) 
      lst.Add(t) 
      t.Start(bump) 
     Next 



     'test(1) 
    End Sub 
End Class 

Answer 1

有兩種方法2實現這一目標：

首先，如果你正在使用.NET 4.0，您可以使用Parallel.ForEach循環：

 Parallel.ForEach(RichTextBox1.Lines, Function(line As String) 
              ' Do something here 
              ' To update the GUI use: 
              Me.Invoke(Sub() 
                  ' Update GUI like this... 
                 End Sub) 
              Return Nothing 
             End Function) 

另一種方法是手動執行此操作（並且您w生病有稍微更多的控制）：

Dim lst As New List(Of Threading.Thread) 
    For Each line In RichTextBox1.Lines 
     Dim t As New Threading.Thread(Function(l As String) 
              'Do something with l 
              'Update GUI like this: 
              Me.Invoke(Sub() 
                 'Update Gui... 
                End Sub) 
             End Function) 
     lst.Add(t) 
     t.Start(line) 
    Next 

這兩個都是非常粗糙的，但將完成工作。

編輯：

這裏是一個示例代碼，將控制線程的數量：

Dim lst As New List(Of Threading.Thread) 
    Dim n As Integer = 1 ' Number of threads. 
    Dim npl As Integer = RichTextBox1.Lines/n 
    Dim seg As New List(Of String) 
    For Each line In RichTextBox1.Lines 
     For i = npl - n To npl 
      seg.Add(RichTextBox1.Lines.Item(i)) 
     Next 
     Dim t As New Threading.Thread(Function(l As String()) 
              For Each lin In l 
               ' TO-DO... 
              Next 
              'Do something with l 
              'Update GUI like this: 
              Me.Invoke(Sub() 
                 'Update Gui... 
                End Sub) 
             End Function) 
     lst.Add(t) 
     t.Start(seg.ToArray()) 
    Next 

* 上面的代碼可能有缺陷。