vb.net timer and exception (try... catch) and memory leak

Scenario: I've hundreds of applications instances running on client machines doing a certain job. Something like a cloud app.

Objective: When an error occur in any of them i want to report the error to an error-log database an quit silently the app to avoid user annoyance.

The problem: I've migrate开发者_开发技巧 to VB.NET recently and don't know yet wich is the best aproach to error handle the code. Those instances are runing a routine under a timer.

Private Sub timerLifeSignal_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles timerLifeSignal.Tick
    MAINSUB()
End Sub

Friend Sub MAINSUB()
    frmSAN.timerLifeSignal.Enabled = False
    ...
    'do the job
    ...
    frmSAN.timerLifeSignal.Enabled = True
end sub

At first glance i've put try/catch into every single function but it leads to a memory leak since, AFIK, the exception object created was not disposed correctly.

So is there a way to make try/catch do not memory leak under these circumstances?

Thx,

UPDATE: Basically what i was doing is something like:

Private Sub timerLifeSignal_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles timerLifeSignal.Tick
    MAINSUB()
End Sub

Friend Sub MAINSUB()
    Try
        frmSAN.timerLifeSignal.Enabled = False
        ...
        'do the job
        ...
        frmSAN.timerLifeSignal.Enabled = True

    Catch ex as Exception : gERRFUNC(" | MAIN | " & ex.Message) : End Try
end sub

friend sub dothejob
    try
        ...
        ' really do the job
        ...
    Catch ex as Exception : gERRFUNC(" | MAIN | " & ex.Message) : End Try
end sub

and so on... and finally (may here it's my mistake) another try/catch nested into here:

Public Sub gERRFUNC(Optional ByVal errorMSG As String = "")
    Try

        ' log message on database
        SQL = "INSERT INTO sanerrorlog VALUES (NULL, '" & currentMySQLTime() & "', '" & errorMSG & "');"
' function that open conn and execute the sql... working fine           
' NOTE THAT INSIDE THE DORS FUNCTION THERE'S ALSO A TRY/CATCH USING THE SAME EX OBJECT. 
        DORS(SQL) 
        ' clean up things
        SQL = "DELETE FROM sannie WHERE sid=" & gMyID
        DORS(SQL)
        For i = 0 To UBound(gCONN)
            If gCONN(i).State = ConnectionState.Open Then gCONN(i).Close()
        Next

        frmSAN.nfi.Visible = False
        gWWB = Nothing
        End
    Catch E As Exception:   End:        End Try
End Sub

So... if i do this:

    Private Sub timerLifeSignal_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles timerLifeSignal.Tick
Try
        MAINSUB()
Catch ex as Exception : gERRFUNC(" | MAIN | " & ex.Message) : End Try
    End Sub

Means all exceptions inside mainsub should be catched?

---

You have another way..

You can attach events to the app domain and main thread, in case it fails, to catch the errors.

Something like:

    AppDomain.CurrentDomain.UnhandledException +=
     CurrentDomain_UnhandledException;
    Application.ThreadException +=
      Application_ThreadException;
    Application.ApplicationExit += Application_ApplicationExit;

with this in mind, every time an exception occurs, anywhere that it hasn't a catch by itself, will fall trough any of this ones...

---

Try/Catches by themselves don't cause memory leaks. Not finalizing something after a failure, which triggers a catch can however. By removing your try/catches, you've apparently exposed something else that does finalize, even though informally, the object which was causing a memory leak.

Ask yourself this, how could a directive in your code cause a memory leak? Try, nor Catch are references to an object, and thus could not cause memory consumption issue by themselves -- only by the logical path of the code they control.

---

Just for reference the memory leak problem occurs because of nested try/catch loops wich (by my mistake) uses the same variable as exception object. To be more clear take the following example:

Public Sub gERRFUNC(Optional ByVal errorMSG As String = "")
    Try
      // do something wrong here
    Catch E As Exception: gERRFUNC(ex.Message): End Try
End Sub

friend Sub gERRFUNC(msg as string)
    Try
        // call another external sub (wich eventually may also throw an execption)
        // take note that the var 'E' is also referenced here and everywhere
        // so as 'E' is set it enters on a Exception loop causing the 'memory leak' problem.
    Catch E as Exception: End: End Try
End Sub

By removing the nested try/catch or by using a well structured error 'flow' may avoid these type of problem.

Best Regards, Paulo Bueno.