Monitoring processes to see if they've crashed in vb6

Question

I've got a program that tends to crash quite often while I'm asleep and I need to keep it running. So I thought I might writeup a vb6 application that monitors the process list, if something disappears it will relaunch it. Anyone know of an easy way?

Answer 1

Use WMI.

If you're stuck with VB6, search the web for WMI+VB6.
Otherwise, interfacing c# and WMI is much easier.

Answer 2

I've used scheduled task (running at each 10 min), starting cmd file with next content:

tasklist |find "myapp.exe" >nul || c:\mypath\myapp.exe

You can execute such command file from VB6 Shell or just use Task Scheduler :)

Answer 3

I use a program that runs other programs. That way you can poll the process handle to see if the application is still running. If not you can launch it again. It does require API programming.

Answer 4

You could use EnumProcesses to list every process in the system at the moment you're running you could use this declaration to use it

Public Declare Function EnumProcesses Lib "psapi.dll" ( _
                                      ByRef idProcess As Long, ByVal cb As Long, _
                                      ByRef cbNeeded As Long) As Long

Prior using it you should define an array of Long to pass as an argument to EnumProcesses with enough space to read all processes ids. You could call EnumProcesses twice to discover how large that array should be. After the second call you could start looping through that array and opening the processes obtaining that way a handle which used appropriately can tell you the name of the process executable and comparing that data with the name of the executable you're searching you are done. Otherwise if what you're looking for is a DLL for example you could EnumProcessModules for that process handle searching for each running process for the dll you're looking for. the declaration of EnumProcessModules is this

    Public Declare Function EnumProcessModules Lib "psapi.dll" ( _
                                               ByVal hProcess As Long, ByRef lphModule As Long, _
                                               ByVal cb As Long, ByRef cbNeeded As Long) As Long

and the probable code you'd need would be something like this

Option Explicit

Private Declare Function OpenProcess Lib "Kernel32.dll" ( _
                                    ByVal dwDesiredAccessas As Long, ByVal bInheritHandle As Long, _
                                    ByVal dwProcId As Long) As Long
Private Declare Function EnumProcesses Lib "psapi.dll" ( _
                                      ByRef lpidProcess As Long, ByVal cb As Long, _
                                      ByRef cbNeeded As Long) As Long
Private Declare Function GetModuleFileNameExA Lib "psapi.dll" ( _
                                             ByVal hProcess As Long, ByVal hmodule As Long, _
                                             ByVal moduleName As String, ByVal nSize As Long) As Long
Private Declare Function EnumProcessModules Lib "psapi.dll" ( _
                                           ByVal hProcess As Long, ByRef lphModule As Long, _
                                           ByVal cb As Long, ByRef cbNeeded As Long) As Long
Private Declare Function TerminateProcess Lib "kernel32" (ByVal hProcess As Long, ByVal uExitCode As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long

Private Const PROCESS_ALL_ACCESS         As Long = &H1F0FFF

Public Function IsModuleRunning(ByVal theModuleName As String) As Boolean
    Dim aProcessess(1 To 1024)  As Long ' up to 1024 processess?'
    Dim bytesNeeded             As Long
    Dim i                       As Long
    Dim nProcesses              As Long
    Dim hProcess                As Long
    Dim found                   As Boolean

    EnumProcesses aProcessess(1), UBound(aProcessess), bytesNeeded
    nProcesses = bytesNeeded / 4
    For i = 1 To nProcesses

        hProcess = OpenProcess(PROCESS_ALL_ACCESS, False, aProcessess(i))
        If (hProcess) Then
            Dim hmodule(1 To 1024)  As Long ' no more than 1024 modules per process?'
            bytesNeeded = 0
            If EnumProcessModules(hProcess, hmodule(1), 1024 * 4, bytesNeeded) Then
                Dim nModules    As Long
                Dim j           As Long
                Dim moduleName  As String

                moduleName = Space(1024)   ' module name should have less than 1024 bytes'

                nModules = bytesNeeded / 4
                For j = 1 To nModules
                    Dim fileNameLen As Long
                    fileNameLen = GetModuleFileNameExA(hProcess, hmodule(j), moduleName, 1024)
                    moduleName = Left(moduleName, fileNameLen)
                    If Right(LCase(moduleName), Len(theModuleName)) = LCase(theModuleName) Then
                        found = True
                        Exit For
                    End If
                Next
            End If
        End If
        CloseHandle hProcess
        If found Then Exit For
    Next
    IsModuleRunning = found
End Function

Private Sub Form_Load()
    MsgBox IsModuleRunning("explorer.exe")
End Sub

function code is a little long but calling it is a little function, you may use it if you want to test it a little :)