App "NOT RESPONDING" on opening some other window

All Time Programming

Hi, I have devloped an desktop application in Vb.NET somthing of importing/updating data with SQL server. App works fine as expected, but when the databse process is going on & if I open any other window then the application shows "Not Responding" on top, part of app window that has components turns white, text/components r not visible or doesn't show update in TextBox BUT the application is running in back & updating the data lying on server. Due to this I can't know the status of the Import + "Not Responding" on title bar gives the msg that something has gone wrong & an error has occured (but actually no error has occured). Can anyone tell why does this happen & how to overcome this problem. Any help/guidance is highly appreciated.

Thanks & Regards,

Dave Kreskowiak

This usually happens because you have a long running process executing on the UI thread, namely, your database processing. You have to move that processing to a background thread in order to keep the UI responsive and painting itself (the white window goes away).

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Dave Kreskowiak

All Time Programming

Thanks Dave, but the UI is related to DB processing. On updating DB, msg is shown on Textbox, so textbox updating is related to db processing. Then yet, in that case will the threading be useful ? My code is such : sub StartProcessing() ' Perform Main Main_Processing() ' Perform Other Other_Processing() ' Item Processing Item_Processing() return End sub sub Main_Processing() .... .... cmd.Execute("Update .......") statusTxt.AppendText("Updated document # ...") end sub How & where do I add Thread.Run....

Thanks & Regards,

Dave Kreskowiak

StartProcessing would launch the thread that executes everything else. Any UI updates (TextBox messages) would have to be Invoke a method on the UI thread that updates the control. Read this article[^]

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Dave Kreskowiak

All Time Programming

Hi Dave, Learning from the article you provided, I did sme homework. I think I am going somewhere wrong, Can you please check it. Actually have never worked with Threading with .NEt, have worked with Java. Private Delegate Sub ControlStringConsumer(ByVal control As Control, ByVal text As String) ' defines a delegate type ' SetTextData to update text of TextBox (statusTxt) Private Sub SetTextData(ByVal control As Control, ByVal text As String) If (control.InvokeRequired) Then control.Invoke(New ControlStringConsumer(AddressOf SetTextData), New Object() {control, text}) Else control.Text = text End If End Sub ' Update Imported Private Sub updateBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles updateBtn.Click If (ValidateInputs()) Then importAdd = False ' ADDED THREADING EXECUTION FOR Start_Processing Dim myThreadDelegate As New ThreadStart(AddressOf Start_Processing) Dim myThread As New Thread(myThreadDelegate) myThread.Start() 'Start_Processing() End If End Sub Private Sub Start_Processing() 'statusTxt.AppendText(vbCrLf + "Initializing...." + vbCrLf + "Loading Data........." + vbCrLf) dim s as string = vbCrLf + "Initializing...." + vbCrLf + "Loading Data........." + vbCrLf SetTextData(statusTxt, s) ......... Endif I feel the Threading part is correct - maybe can remove ThreadStart & straight away give AddOf to Thread(). But feel their is somethign wrong with SetTextData. Here I want to AppendText & not only set some new value to it. If this is the right way to do, then everytime I will have to call it as :- dim s as string = statusTxt.Text + vbcrlf + " MY NEW TExT" + vbcrlf SetTextData(statusTxt, s) OR is it so that I should overwrite AppendText instead of SetText & SetText should be used & not SetTextData ???? What do u say, am I going anywher wrong. Don't know why, but this time feeling scared to run without confirmity. Maybe b'coz using Threads. I know how unsafe threads can be if not operated properly.

Thanks & Regards,

Luc Pattyn

Your code looks basically OK, assuming SetTextData() is not directly manipulating a GUI Control. Similar to (from the article):

public void SetText(Control control, string text) {
if (control.InvokeRequired) {
control.Invoke(new ControlStringConsumer(SetText), new object[]{control, text}); // invoking itself
} else {
control.Text=text; // the "functional part", executing only on the main thread
}
}

you should do:

public void AppendText(TextBox control, string text) {
if (control.InvokeRequired) {
control.Invoke(new ControlStringConsumer(AppendText), new object[]{control, text}); // invoking itself
} else {
control.AppendText(text); // the "functional part", executing only on the main thread
}
}

:)

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All Time Programming

Thanks Dave & Luc. But am getting error : ERROR: Cross-thread operation not valid: Control 'statusTxt' accessed from a thread other than the thread it was created on Luc, I added AppendText as you mentioned ad removed SetTextData which was wrong. Same way added Thread, and my code is as below :

Private Delegate Sub ControlStringConsumer(ByVal control As Control, ByVal text As String)    ' defines a delegate type

Private Sub importNewBtn\_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles importNewBtn.Click
    If (ValidateInputs()) Then
        'Start\_Processing()
        Dim myThreadDel As New ThreadStart(AddressOf Start\_Processing)
        Dim myThread As New Thread(myThreadDel)
        myThread.Start()
    End If
End Sub

Public Sub AppendText(ByVal control As TextBox, ByVal text As String)
    If (control.InvokeRequired) Then
       ' invoking itself SHOWS WARNING - IMPLICIT CONVERSION FROM CRONTROL TO TEXTBOX
        control.Invoke(New ControlStringConsumer(AddressOf AppendText), New Object() {control, text})  
    Else
        control.AppendText(text)      ' the "functional part", executing only on the main thread    
    End If
End Sub

Private Sub Start\_Processing()
    EnableComponents(False)
    statusTxt.Clear()  ' ---- GENERATING ERROR

    statusTxt.AppendText(vbCrLf + "Initializing...." + vbCrLf + "Loading Data........." + vbCrLf)
    ' Load all required basic Data
    If (setUp() = False) Then
        Return
    End If

    statusTxt.AppendText(vbCrLf + "Generating....." + vbCrLf)
    GenerateQueries()
    statusTxt.AppendText(vbCrLf + "Data Set Up Completed - " + Now.ToString + vbCrLf)

    ' ADD ALL RECORDS OF main TO REGISTER
    statusTxt.AppendText(vbCrLf + "Processing Main transactions ..... " + Now.ToString + vbCrLf)
    MainProcessing()

    ' Update UFV records to Register
    statusTxt.AppendText(vbCrLf + "Processing UFV transactions ..... " + Now.ToString + vbCrLf)
    UFVProcessing()

    ' Update Item records to Register
    statusTxt.AppendText(vbCrLf + "Processing Item transactions ..... " + Now.ToString + vbCrLf)
    ItemProcessing()

    ' Update Tax records to register
    statusTxt.AppendText(vbCrLf + "Processing Tax transactions ..... " + Now.ToString + vbCrLf)
    TaxProcessing()

    ' Update Qty, Rate records to Register

Luc Pattyn

1. So you added my Sub AppendText, however you are not calling it anywhere. All statusTxt.AppendText(someString) have to be replaced by AppendText(statusTxt, someString), I thought that was obvious to anyone who read my article. 2. statusTxt.Clear() is also forbidden, it needs similar treatment. 3. the warning is my fault, you have to define (and use) new delegates, so make an almost clone of ControlStringConsumer. I suggest you read the article again until you understand what should and shouldn't be done with Controls. :)

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modified on Monday, September 27, 2010 2:13 PM