VB.net多线程for循环，并行线程

Question

我有一个带有 2 个 RichTextBox 和 1 个按钮的简单表单，代码从 RichTextBox1 中获取 url 地址，并使用正则表达式为标题字段的页面添加短语，并将其附加到 RichTextBox2。我想以这样的方式对所有内容进行多线程处理，即不跳过任何 url 并且可以设置线程数(根据系统可用资源)例如，假设 10 个线程并行运行。我搜索了所有内容，我设法做的最好的事情就是在后台工作程序中运行所有内容，并防止 GUI 在工作时卡住。一个简短的代码示例会有很大帮助，我是 VB.net 的初学者。

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

更新了代码(抛出“Index was outside the bounds of the array.”错误。)

    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

有两种实现方式:

首先，如果您使用的是 .NET 4.0，则可以使用 Parallel.ForEach 循环:

        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)

另一种方法是手动执行此操作(您将拥有更多控制权):

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

这两个都非常粗糙，但可以完成工作。

编辑:

下面是一个控制线程数的示例代码:

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

*上面的代码可能有错误。