UI Threading

RealistSpy

Hi,

How are you all?
I have been having a bit of problems regarding multi threading.
Basically how do I cross threads safely because i need to get/set informations to the UI controls.

Without thread the UI freezes till work is finished while showing "not responding" with threading it still shows "not responding" but the UI is not frozen.

Rough Work

Snippit - Button Click - UI Thread

Dim oThread As Threading.Thread = New Threading.Thread(New Threading.ThreadStart(AddressOf work))

        If Not saveFilePath = Nothing Then
            If ComboBox1.Text = Nothing Then
                MessageBox.Show("Select Your Character", "Reader", MessageBoxButtons.OK, MessageBoxIcon.Stop)
            Else
                ToolStripStatusLabel2.Text = "Loading"
                Application.DoEvents()
                oThread.Start()

Snippit - Work Thread

Public Sub work() 'As Object
        If ComboBox1.InvokeRequired Then
            ComboBox1.Invoke(New MethodInvoker(AddressOf work))
        Else
            TextBox1.Text = ReadModule.readCLevel(saveFilePath, ComboBox1.Text).ToString
            Dim tempCoin As Integer = ReadModule.readCCoins(saveFilePath, ComboBox1.Text)

            If tempCoin > 9999999 = True Then
                NumericUpDown2.Value = NumericUpDown2.Maximum
            Else
                NumericUpDown2.Value = tempCoin
            End If
            TextBox2.Text = ComboBox1.Text
            TextBox3.Text = ComboBox1.Text
            TextBox4.Text = ComboBox1.Text

            If Integer.Parse(TextBox1.Text) = 30 Then
                NumericUpDown1.Value = 30
            Else
                NumericUpDown1.Value = Integer.Parse(TextBox1.Text) + 1
            End If
            ' Return Nothing
        End If

    End Sub

stevenmu

Your worker thread shouldn't referring to your UI controls directly, I'm not sure but I guess that's why you're still getting the 'Not Responding' message.

Your UI thread should contain a method for updating your UI controls, it takes in whatever values needed as parameters. Your UI thread can then pass it as a delegate to your worker thread which calls it passing the values as needed.

fasty

Since you call work on another thread, then check if an invoke is required to update the combo box, which is always is, you then invoke do work on the UI main thread anyway, defeating the purpose of threading!

It should be something like this:

Pass all params needed to background thread, so values from UI etc
Do work
Check if invoke required on controls you want to update
If so, use invoke pattern to update controls
return

stevenmu wrote: »

Your worker thread shouldn't referring to your UI controls directly, I'm not sure but I guess that's why you're still getting the 'Not Responding' message.

Your UI thread should contain a method for updating your UI controls, it takes in whatever values needed as parameters. Your UI thread can then pass it as a delegate to your worker thread which calls it passing the values as needed.

If you try to update UI components in .Net without using the invoke pattern, it'll throw an InvalidOperation exception rather than cause the app to become unresponsive.