VB.net Windows窗体中的尝试-多线程

当线程第一次命中SetLabelText2时,InvokeRequired将为true,因此

Invoke(New UpdateDelegate(AddressOf SetLabelText2))

将被调用。

现在,Invoke调用内部实际发生的情况是,您的线程将把委托作为任务传递给UI线程。因此,对SetLabelText2的第二个递归调用将由UI线程完成,而您的线程只是坐着等待UI线程从SetLabelText2返回。因此,您的UI会阻塞,因为UI线程将处于循环中,设置标签文本并休眠,并且没有机会处理消息/事件。

作为一种解决方案,您可以在循环中调用Application.DoEvents(),而不是Sleep(200),但这可能会产生副作用,不建议这样做。

更好的解决方案是将Invoke限制为严格必要的UI调用,在您的示例中:

Private Sub SetLabelText2()
    For i = 1 To 110
        'Label2.Text = Text
        Invoke(MyDelegateThatDoesNothingButSettingTheLabelText)
        Threading.Thread.Sleep(200)
    Next
End Sub

现在,睡眠将由您的线程完成,并且您的用户界面保持响应。

您的第一个问题是,由于Invoke,SetLabelText2中的Sleep是在UI线程上调用的,而不是在后台线程上调用。这将导致UI显示为锁定状态。新线程仅用于启动SetLabel,但工作几乎立即返回到调用线程。相反,您需要调用循环内部的后台任务,并为每次标签更新委派回UI。

其次,在这个例子中,您不应该创建显式线程。从.Net 4开始,您应该使用Tasks。要模拟使用Thread.Sleep时长时间运行的操作,请使用Task.Delay(200),然后Await或call。显式等待。请记住在后台线程上安排延迟,并委托回UI更新。

好吧,多亏了本节的评论和一些研究的帮助,我终于明白了。

我有点作弊,因为我运行UI线程,只为了在循环或短时间内完成繁重的工作,这里有一些代码-希望这能帮助其他人。

Public t2 As Threading.Thread ' Instantiating the Thread. I do this in my Modules
                              ' You will want to do this for all threads needed.

'You would then go through your program like normal until you hit a heavy process eating point,
'For me it was when i was converting images and sending them / moving them across the network

'So to get what i wanted i used this in the middle of my public Function

    For Each s As String In sFiles
        c += 1 'This was just a simple file counter for the prg bar

CheckAgain:
        If t3 Is Nothing Then
            t3 = New Thread(New ParameterizedThreadStart(AddressOf DoWork))
            t3.Start(s)
            GoTo NextOne
        ElseIf t4 Is Nothing Then
            t4 = New Thread(New ParameterizedThreadStart(AddressOf DoWork))
            t4.Start(s)
            GoTo NextOne
        ElseIf t5 Is Nothing Then
            t5 = New Thread(New ParameterizedThreadStart(AddressOf DoWork))
            t5.Start(s)
            GoTo NextOne
        ElseIf t6 Is Nothing Then
            t6 = New Thread(New ParameterizedThreadStart(AddressOf DoWork))
            t6.Start(s)
            GoTo NextOne
        ElseIf t7 Is Nothing Then
            t7 = New Thread(New ParameterizedThreadStart(AddressOf DoWork))
            t7.Start(s)
            GoTo NextOne
        ElseIf t8 Is Nothing Then
            t8 = New Thread(New ParameterizedThreadStart(AddressOf DoWork))
            t8.Start(s)
            GoTo NextOne
        ElseIf t9 Is Nothing Then
            t9 = New Thread(New ParameterizedThreadStart(AddressOf DoWork))
            t9.Start(s)
            GoTo NextOne
        Else
            GoTo CheckAgain
        End If
NextOne:
    Next

Sub DoWork(ByVal s As Object)

        ChangeCompression("Variables for my Function that did alot of work")
        'System.Threading.Thread.Sleep(10)

    'This is how i disposed of my threads

    If Not (t3 Is Nothing) Then
        t3 = Nothing
    ElseIf Not (t4 Is Nothing) Then
        t4 = Nothing
    ElseIf Not (t5 Is Nothing) Then
        t5 = Nothing
    ElseIf Not (t6 Is Nothing) Then
        t6 = Nothing
    ElseIf Not (t7 Is Nothing) Then
        t7 = Nothing
    ElseIf Not (t8 Is Nothing) Then
        t8 = Nothing
    ElseIf Not (t9 Is Nothing) Then
        t9 = Nothing
    End If

End Sub

这就是全部:)-希望这能帮助到别人,并感谢所有人帮助我完成我的多线程,是的。。。我知道有更好的方法,但这一种对我有效:)