VB.NET Progress status while run a EXE file

[Andraw Tang]

I found only if I clearly call p.Kill(), the Exited event will be triggered, but when I should call the .Kill() for a process? if I use p.WaitForExit(5400000), the program will be hanged to wait for process to exit, the progressbar form will be hanged.

[Dave Kreskowiak]

The process will drop by itself. You shouldn't have to call Kill on it at all. Once the process you launched quits on its own, the Exited event will be raised. 5400000?? Really? 90 minutes?? You do realize WaitForExit is a blocking call, right? No other code will execute so long as WaitForExit is waiting. Remove this line and just let it run. When the target app is finished, your event handler will get called.

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Dave Kreskowiak

[Andraw Tang]

That's the whole codes when "Run" is clicked. Yes, I need to waiting for the process to exit, I need to get the return string and display them in the form. That's why I use p.WaitForExit(5400000). But use p.WaitForExit(5400000) will hang progressbar form, if don;t use p.WaitForExit(5400000), when should I close the progressbar form?

 Private Sub OnProcesited(ByVal sender As Object, ByVal e As System.EventArgs)
    Dim p As System.Diagnostics.Process
    p = sender

    Dim rtnStr As String = String.Empty
    **rtnStr = p.StandardOutput.ReadToEnd()**

    If rtnStr.Contains(" FAST terminated normally.") = True Then
        rtnStr = rtnStr & vbCrLf & "Please click Postprocess -> View Output File in menu to view the file."
        updateViewMenu()
    End If
    '''progBarFrm.Close()
    '''progBarFrm.Dispose()
    **
    Dim frm As New FormShowFASTResult
    frm.txtFASTResult.Text = rtnStr
    frm.Button1.Select()
    frm.ShowDialog()**
  End Sub

[Andraw Tang]

Progressbar value should be updated using timer inside the form, after call SHOW of the form, the timer will be started, sure you cannot see these codes from inside the function which create the form.

[Andraw Tang]

Sorry calculation error, I already comment out that line. Now I modify the source codes, also remove the event. When "Run" menu is clicked, it will call Run_Tool() inside which it start a precess and open a form, I also show the codes for progressbar form below, but the progressbar color is grayed, no value is shown. Would you please take a look where is wrong? thanks!

  Private Sub Run\_Tool()

    Dim sAppPath As String = ".\\xxxx.exe"
    Dim fileName As String = "XXXXXX.TXT"
    Dim p As New System.Diagnostics.Process()

    Dim rtnStr As String = String.Empty

    p.StartInfo.FileName = Application.StartupPath & "\\" & sAppPath
    p.StartInfo.Arguments = fileName

    'Do not use the system shell to start the program this is so we can hide the command dos window
    p.StartInfo.UseShellExecute = False
    p.StartInfo.WorkingDirectory = strOutputFilePath
    ' Show no dos window if false
    p.StartInfo.CreateNoWindow = True
    p.StartInfo.RedirectStandardOutput = True

    Dim progBarFrm As New FormProgressBar
    progBarFrm.Show()


    Try
        p.Start()
    Catch ex As Exception
        ShowValidationMessage("Unexception error is caught, please close and try again.", "Error")
        'p.Kill()
        progBarFrm.Close()
        Return
    End Try


    rtnStr = p.StandardOutput.ReadToEnd()

    ''p.WaitForExit(120000)   '= 1.5 min: 1000 millisecond = 1 second
    ' if the process doesn't complete within 5400 seconds, kill it
    ''If Not p.HasExited Then
    ''p.Kill()
    ''End If

    If rtnStr.Contains(" FAST terminated normally.") = True Then
        rtnStr = rtnStr & vbCrLf & "Please click Postprocess -> View Output File in menu to view the file."
        updateViewMenu()
    End If
    progBarFrm.Close()

    Dim frm As New FormShowFASTResult
    frm.txtFASTResult.Text = rtnStr
    frm.Button1.Select()
    frm.ShowDialog()      

End Sub

Source code for the progressbar form as the following

Public Class FormProgressBar

Private Sub FormProgressBar\_Disposed(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Disposed
    Timer1.Stop()
End Sub



Private Sub FormProgressBar\_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Me.CenterToScreen()
    ProgressBar1.Mi

[Andraw Tang]

If I don't start the process, the progressbar in the form works fine. So the p.Start action hang the progressbar form.

 Private Sub Run\_FAST\_Tool()

    Dim sAppPath As String = ".\\FAST.exe"
    Dim fileName As String = objFASTPrimaryData.FASTPrimaryFileName\_FST
    Dim p As New System.Diagnostics.Process()

    Dim rtnStr As String = String.Empty

    p.StartInfo.FileName = Application.StartupPath & "\\" & sAppPath
    p.StartInfo.Arguments = fileName

    'Do not use the system shell to start the program this is so we can hide the command dos window
    p.StartInfo.UseShellExecute = False
    p.StartInfo.WorkingDirectory = strOutputFilePath
    ' Show no dos window if false
    p.StartInfo.CreateNoWindow = True
    p.StartInfo.RedirectStandardOutput = True

    Dim progBarFrm As New FormProgressBar
    progBarFrm.Show()
end sub

[Dave Kreskowiak]

First, ReadToEnd isn't going to give you what you're looking for. It'll block until the console has to something to return, and even then, it'll return block of text, most likely NOT all of the text your app output to the console, and it will only read ONE block of text. Now, if you want to gather all the text the app outputs, and still have a responsive UI (such as the progress bar redrawing itself), you'll have to read the console output asynchronously. Something like:

Private Sub StartConsoleRead(ByRef st As Stream)
Dim rdo As New ReadData
'rdo.s = _conStream.BaseStream
rdo.s = st

    Dim consoleReadAsyncCallback As New AsyncCallback(AddressOf ConsoleReadCallback)
    \_conStream.BaseStream.BeginRead(rdo.buffer, 0, rdo.buffer.Length, consoleReadAsyncCallback, rdo)
End Sub

Private Sub ConsoleReadCallback(ByVal asyncResult As IAsyncResult)
    Dim rdo As ReadData = DirectCast(asyncResult.AsyncState, ReadData)
    Dim bytesRead As Integer = rdo.s.EndRead(asyncResult)
    Dim enc As Encoding = Encoding.ASCII
    Dim s As String = enc.GetString(rdo.buffer, 0, bytesRead)

    CmdOutput.Invoke(UpdateCmdOutputDelegate, New Object() {s})
    StartConsoleRead(rdo.s)
End Sub

Public Class ReadData
Public buffer(20480) As Byte
Public s As Stream
End Class

Also, you're Timer.Interval on the progress bar form should not be 1. Make it something more reasonable, like 250 to 500 (quarter to half a second). Setting it to one will just make your app hog the CPU.

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Dave Kreskowiak

[Dave Kreskowiak]

The reason why your UI thread blocks is not because you started the process. It's blocking because of another line AFTER your call to Start. Your executing some statement that blocks, like WaitForExit, freezing your UI. You cannot do that and expect your UI to update itself.

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Dave Kreskowiak

[Andraw Tang]

Thanks, David. After I remove calling WaitForExit() and ReadToEnd(), the progressbar works now, but the Exited event function OnProcesited is not called, so the progressbar is always shown. How can I make OnProcesited() be called?

Private Sub OnProcesited(ByVal sender As Object, ByVal e As System.EventArgs)
Dim p As System.Diagnostics.Process
p = sender

    Dim rtnStr As String = String.Empty
    rtnStr = p.StandardOutput.ReadToEnd()

    If rtnStr.Contains(" FAST terminated normally.") = True Then
        rtnStr = rtnStr & vbCrLf & "Please click Postprocess -> View Output File in menu to view the file."
        updateViewMenu()
    End If
    progBarFrm.Close()
    progBarFrm.Dispose()

    Dim frm As New FormShowFASTResult
    frm.txtFASTResult.Text = rtnStr
    frm.Button1.Select()
    frm.ShowDialog()

End Sub


Private Sub Run\_Tool()

    Dim sAppPath As String = ".\\XXXXX.exe"
    Dim fileName As String = "XXXXX.txt"
    Dim p As New System.Diagnostics.Process()



    p.StartInfo.FileName = Application.StartupPath & "\\" & sAppPath
    p.StartInfo.Arguments = fileName

    'Do not use the system shell to start the program this is so we can hide the command dos window
    p.StartInfo.UseShellExecute = False
    p.StartInfo.WorkingDirectory = strOutputFilePath
    ' Show no dos window if false
    p.StartInfo.CreateNoWindow = True
    p.StartInfo.RedirectStandardOutput = True
    p.EnableRaisingEvents = True
    AddHandler p.Exited, AddressOf OnProcesited


    progBarFrm = New FormProgressBar

    Try
        p.Start()

        progBarFrm.Show()
        progBarFrm.Refresh()            
    Catch ex As Exception
        ShowValidationMessage("Unexception error is caught, please close and try again.", "Error")
        
        Return
    End Try    

End Sub

[Dave Kreskowiak]

You can't force it. Your external process just hasn't stopped yet for some reason. Does your external process wait for the user to "Press any key to exit"?? I sure hope not!

A guide to posting questions on CodeProject[^]
Dave Kreskowiak