Is This App Running?

[Semen Matusovski]

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

#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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[Lance Edmonds]

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>

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.