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Is This App Running?

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  • Is This App Running?

    Does anyone know how to detect if an application is 'Running'? The NT Task Manager lists all Apps and if they are 'Running' or 'Not Responding'.

    I would like to create a program that starts an App. and then monitors it so that if it hangs, posts an error or whatever the App. can be stopped and restarted.

  • #2
    I think the most common method is to use SendMessageTimeout() and if the app does not respond after a reasonable period, the app is considered as "frozen" or "not responding".

    It is interesting to note that if one app hogs the CPU, the others face CPU starvation, and sometimes become labeled by Task Manager as "Not responding", and then will come back to life again. Essentially, determining if an app has really frozen is not an exact science.

    Another way to approach the problem (since you are using NT) could be to write the app as an NT Service, and let NT do the monitoring, and optionally notify and/or reboot if the app fails.

    There is some example code in the Source Code forum showing how to create an NT service.

    ------------------
    Lance
    PowerBASIC Support
    mailto:[email protected][email protected]</A>
    Lance
    mailto:[email protected]

    Comment


    • #3
      Larry --
      If it's interesting, you can test one fragment from my "hot reserve".
      This code is based on undocumented functions in User32.Dll.

      Code:
      #Compile Exe
      #Dim All
      #Register None
      #Include "Win32Api.Inc"
      $AppTitle = "Ltr" ' <--------------- Change me
      
      Declare Function MySubCall(hWnd As Long) As Long
      
      Function PbMain
      
      Dim hWnd As Long, hUser32 As Long
      Do
         hWnd = FindWindow (ByVal %Null, $AppTitle)
         If IsWindow(hWnd) = %False Then Exit Do
         hUser32 = GetModuleHandle("user32.dll")
         If hUser32 = 0 Then Exit Do
         Dim IsHungAppWindow As Dword, IsHungThread As Dword
      
         Dim os As OSVERSIONINFO
         os.dwOSVersionInfoSize = SizeOf(os)
         GetVersionEx ByVal VarPtr(os)
         Dim IsHung As Long
         If IsTrue(os.dwPlatformId = %VER_PLATFORM_WIN32_NT) Then
            IsHungAppWindow = GetProcAddress(hUser32, "IsHungAppWindow")
            If IsHungAppWindow = 0 Then Exit Do
            Call Dword IsHungAppWindow Using MySubCall(100) To IsHung
         Else
            IsHungThread = GetProcAddress(hUser32, "IsHungThread")
            If IsHungThread = 0 Then Exit Do
            Dim ThreadId As Long
            ThreadId = GetWindowThreadProcessId(hWnd, %Null)
            Call Dword IsHungThread Using MySubCall(ThreadId) To IsHung
         End If
         If IsTrue(IsHung) Then IsHung = 2 Else IsHung = 1
         Exit Do
      Loop
      Select Case IsHung
        Case 0: MsgBox "Not found"
        Case 1: MsgBox "Running"
        Case 2: MsgBox "Not responding"
      End Select
      
      End Function
      ------------------

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