a sendasync mail function, do you see any potential memory leak? - vb.net

Question

I have that code running into a windows service and the service seem to have a memory leak, something is wrong for sure.
After looking at the whole code, I think it might be inside one of these function but I cannot seem to find where it could be.
Anyone could take a look and could let me know if something is wrong?
thanks for any kind of help.
Public Function sendEmail(Optional ByVal msg As String = "") As Boolean
Dim mailSent As Boolean = False
Dim mail As Net.Mail.MailMessage = Nothing
Dim smtp As Net.Mail.SmtpClient = Nothing
Try
mail = New Net.Mail.MailMessage
mail.From = New Net.Mail.MailAddress("myemail#myaddress.com")
mail.Priority = Net.Mail.MailPriority.High
mail.To.Add("1#1.1")
mail.To.Add("2#1.1")
mail.To.Add("3#1.1")
mail.Subject = "test"
mail.Body = msg
Dim stream As IO.MemoryStream = createReport(Of IO.MemoryStream)()
mail.Attachments.Add(New Net.Mail.Attachment(stream, "Report.html", "text/html"))
smtp = New Net.Mail.SmtpClient("my.smtp.server")
AddHandler smtp.SendCompleted, AddressOf SendCompletedCallback
smtp.SendAsync(mail, mail)
mailSent = True
Catch ex As Exception
Debug.Print(ex.Message)
End Try
If mail IsNot Nothing Then
mail = Nothing
End If
If smtp IsNot Nothing Then
smtp = Nothing
End If
Return mailSent
End Function
Private Sub SendCompletedCallback(ByVal sender As Object, ByVal e As ComponentModel.AsyncCompletedEventArgs)
Try
Dim i As Integer
Dim mail As Net.Mail.MailMessage = CType(e.UserState, Net.Mail.MailMessage)
If e.Cancelled Then
Throw New Exception("Send mail got cancelled")
ElseIf e.Error IsNot Nothing Then
Throw e.Error
End If
For i = (mail.Attachments.Count - 1) To 0 Step -1
mail.Attachments(i).Dispose()
Next
mail.Dispose()
RemoveHandler CType(sender, Net.Mail.SmtpClient).SendCompleted, AddressOf SendCompletedCallback
Catch ex As Exception
Debug.Print(ex.Message)
End Try
End Sub
Public Function createReport(Of dataType)() As dataType
Dim result As Object = Nothing
Dim ds As DataSet = Nothing
Dim xmlDoc As Xml.XmlDocument = Nothing
Dim xslTran As Xml.Xsl.XslCompiledTransform = Nothing
Try
Dim i As Integer
ds = New dsEventLog ''dataset
If IO.File.Exists("c:\myxmlfile") Then
ds.Tables(0).ReadXml("c:\myxmlfile")
For i = ds.Tables(0).Rows.Count - 1 To 0 Step -1
If CDate(ds.Tables(0).Rows(i).Item("LocalTime")) < Now.AddDays(-5) Then
ds.Tables(0).Rows.RemoveAt(i)
End If
Next
End If
xmlDoc = New Xml.XmlDataDocument(ds)
xslTran = New Xml.Xsl.XslCompiledTransform
xslTran.Load("c:\myxslfile")
If GetType(dataType) Is GetType(String) Then
'doesn't matter
ElseIf GetType(dataType) Is GetType(IO.MemoryStream) Then
Dim stream = New IO.MemoryStream
Dim sw As IO.StreamWriter = New IO.StreamWriter(stream)
xslTran.Transform(xmlDoc, Nothing, sw)
stream.Position = 0
result = stream
sw = Nothing
stream = Nothing
Else
Throw New Exception("Incorrect ""Of dataType"" used!")
End If
Catch ex As Exception
Debug.Print(ex.Message)
End Try
If ds IsNot Nothing Then
ds.Dispose()
End If
ds = Nothing
xslTran = Nothing
xmlDoc = Nothing
Return CType(result, dataType)
End Function

Answer 1

You should dispose of the memory stream, by calling the Dispose method. You should also dispose of objects of any class that implements IDisposable to release unmanaged memory.
Also, you don't have to set variables to Nothing. This can actually keep objects in memory longer than they have to.
Edit:
If I'm not mistaken the attachments are disposed but not the stream itself...
Also if you look at the example on MSDN, the mail message is disposed in the main code, not in the callback.
Other problem: If the mail cannot be sent, no Dispose is called. If there is an exception, you don't call dispose either. You should put your Dispose calls in finally blocks so that unmanaged resources are disposed in all cases. Or even better, use Using blocks when you can.