Cannot update textbox vb.net -crossthreading - vb.net

Question

I am trying to make an application to run multiple (adb specially) commands and get the output and display in a label.
First of all, i need to start the process to execute the commands. Thanks to stackoverflow and #pasty I found this (second reply): How to get Output of a Command Prompt Window line by line in Visual Basic?
Well, i thought that because it outputted to the console, it would be simple to just write it to the label. BIG MISTAKE! It gives me a cross threading error!
A little bit of googling and stack overflow I found this: vb.net accessed from a thread other than the thread it was created on
Well, i tried to implement that, but the program just crashes freezes.
Here is the code:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
' store error output lines
Dim executable As String() = {"adb", "adb"}
Dim arguments As String() = {"help", "reboot"}
For i As Integer = 0 To 0
Dim process = New Process()
process.StartInfo = createStartInfo(executable(i), arguments(i))
process.EnableRaisingEvents = True
AddHandler process.Exited, Sub(ByVal sendera As Object, ByVal ea As System.EventArgs)
Console.WriteLine(process.ExitTime)
Console.WriteLine(". Processing done.")
'UpdateTextBox(ea)
End Sub
' catch standard output
AddHandler process.OutputDataReceived, Sub(ByVal senderb As Object, ByVal eb As DataReceivedEventArgs)
If (Not String.IsNullOrEmpty(eb.Data)) Then
Console.WriteLine(String.Format("{0}> {1}", DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss"), eb.Data))
'UpdateTextBox(eb.Data)
End If
End Sub
' catch errors
AddHandler process.ErrorDataReceived, Sub(ByVal senderc As Object, ByVal ec As DataReceivedEventArgs)
Console.WriteLine(String.Format("! {0}", ec.Data))
Dim a As String = String.Format("! {0}", ec.Data)
'UpdateTextBox(a)
End Sub
' start process
Dim result = process.Start()
' and wait for output
process.BeginOutputReadLine()
' and wait for errors :-)
process.BeginErrorReadLine()
process.WaitForExit()
Next
End Sub
Private Sub UpdateTextBox(ByVal a As String)
If Me.InvokeRequired Then
Dim args() As String = {a}
Me.Invoke(New Action(Of String)(AddressOf UpdateTextBox), args)
Return
End If
Label1.Text += "a"
End Sub
Private Function createStartInfo(ByVal executable As String, ByVal arguments As String) As ProcessStartInfo
Dim processStartInfo = New ProcessStartInfo(executable, arguments)
processStartInfo.WorkingDirectory = Path.GetDirectoryName(executable)
' we want to read standard output
processStartInfo.RedirectStandardOutput = True
' we want to read the standard error
processStartInfo.RedirectStandardError = True
processStartInfo.UseShellExecute = False
processStartInfo.ErrorDialog = False
processStartInfo.CreateNoWindow = True
Return processStartInfo
End Function
And the source code: https://github.com/iAmAOpenSource/SyncfusionWindowsFormsApplication3

Answer 1

The call to process.WaitForExit() will block the UI thread until the spawned process exits, but while processing the output in the process.OutputDataReceived event you are calling Me.Invoke which tries to run the code on the UI thread, which is blocked, so the program freezes. You could move the logic in Button1_Click onto another thread, e.g.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Task.Run(
Sub()
... current logic
End Sub
)
End Sub
That way the UI thread won't be blocked and the Me.Invoke call won't cause a deadlock.