databarracks
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Parallel for Each VB or C# sending email issue with attachments
Hi Guys,
I am facing an issue with Parallel for each and adding attachments from a database. What appears to be happening is that the parralel for each starts before the attachment data has been created entirely thus causing the attachments to not have fully been written to memory.
So as an example you will find that if I was sending out 3 emails via parallel for each, the first 2 will have different file sizes (in term of the attachments) and only the last one will have the complete file?
Ok then here is the code that generates the attachments which are stored in a SQL Filetable:
TemplateAttachments is an ObservableCollection of another table in my application
THen the code for actually sending and the Async SMTP SendCompleted Event:
I appreciate that there are variables that you may not get or understand,however the crux of my problem is not that but more of how to ensure that my attachments have been fully loaded prior to starting the parallel for each?
Solutions in C# are more than welcome.
Thank you in advance
I am facing an issue with Parallel for each and adding attachments from a database. What appears to be happening is that the parralel for each starts before the attachment data has been created entirely thus causing the attachments to not have fully been written to memory.
So as an example you will find that if I was sending out 3 emails via parallel for each, the first 2 will have different file sizes (in term of the attachments) and only the last one will have the complete file?
Ok then here is the code that generates the attachments which are stored in a SQL Filetable:
TemplateAttachments is an ObservableCollection of another table in my application
Dim AttachmentFiles As Attachment
Public Sub CreateAttachments()
Dim fileData As Byte() = Nothing
Dim filename As String = Nothing
If TemplateAttachments.Count > 0 Then
TemplateAttachments.ToList().ForEach(Function(i)
Dim conn As New SqlConnection(ConfigurationManager.ConnectionStrings("MyConnectionString").ConnectionString)
Dim strSQL As String = String.Format("SELECT stream_id, file_stream, name, path_locator, parent_path_locator, file_type, cached_file_size, creation_time, last_write_time, last_access_time, is_directory, is_offline, is_hidden, is_readonly, is_archive, is_system, is_temporary FROM dbo.MyFiles WHERE stream_id ='{0}'", i.stream_string_ID)
Dim da As New SqlDataAdapter(strSQL, conn)
Dim ds As New DataSet
da.Fill(ds, "GetStream")
fileData = DirectCast(ds.Tables("GetStream").Rows(0).Item(1), Byte())
filename = ds.Tables("GetStream").Rows(0).Item(2)
Dim ms As New MemoryStream(fileData)
ms.Seek(0, SeekOrigin.Begin)
Dim contentType As New ContentType() With {.MediaType = MediaTypeNames.Application.Octet, .Name = filename}
AttachmentFiles = New Attachment(ms, contentType)
Return AttachmentFiles
End Function)
End If
End Sub
THen the code for actually sending and the Async SMTP SendCompleted Event:
Public Sub SendMethod()
IsSendDialogOpen = False
IsCancelEnabled = False
contacts = (From TblAddresses In _ctx.tblAddresses Where TblAddresses.list_ID = SelectedList.list_ID And TblAddresses.enabled = True And Not TblAddresses.email Is Nothing).ToList
Dim subject As String = SelectedMessage.subject
Dim body As String = "Hi there, This is a test"
CreateAttachments()
Dim po As New ParallelOptions()
_cancelToken = New CancellationTokenSource()
po.CancellationToken = _cancelToken.Token
po.MaxDegreeOfParallelism = System.Environment.ProcessorCount * 2
Try
Parallel.ForEach(contacts.Cast(Of Object), po,
Function(row)
Return SendEmail(row.email, subject, body)
po.CancellationToken.ThrowIfCancellationRequested()
End Function)
Catch e As OperationCanceledException
MessageBox.Show("Your submission was canceled")
Finally
_cancelToken.Cancel()
_cancelToken.Dispose()
_cancelToken = Nothing
End Try
IsSendEnabled = False
IsFinishedEnabled = True
AttachmentsReady = False
End Sub
Private Function SendEmail(recipient As String, subject As String, body As String) As Boolean
Dim mm As New MailMessage(SelectedSMTP.smtp_sender_email, recipient)
mm.Subject = subject
mm.IsBodyHtml = True
mm.Body = body
If IsBCC = True Then
mm.Bcc.Add(SelectedSMTP.smtp_sender_email)
End If
If AttachmentFiles IsNot Nothing Then
mm.Attachments.Add(AttachmentFiles)
End If
Dim smtp As New SmtpClient()
smtp.Host = smtp_name
'smtp.EnableSsl = True
Dim state As [Object] = mm
AddHandler smtp.SendCompleted, AddressOf smtpClient_SendCompleted
Try
smtp.SendAsync(mm, state)
Catch ex As Exception
MsgBox(ex.ToString)
End Try
Return True
End Function
Private Sub smtpClient_SendCompleted(sender As Object, e As System.ComponentModel.AsyncCompletedEventArgs)
Dim token As MailMessage = TryCast(e.UserState, MailMessage)
If e.Cancelled Then
Exit Sub
End If
If e.Error IsNot Nothing Then
Application.Current.Dispatcher.BeginInvoke(DirectCast(Sub() SteppedCollection.Add(New FailedContactList() With {
.FailedEmail = token.To.ToString & " (" & e.Error.Message & ")"
}), Action))
TotalFailed = TotalFailed + 1
Else
TotalSent = TotalSent + 1
End If
End Sub
End Class
I appreciate that there are variables that you may not get or understand,however the crux of my problem is not that but more of how to ensure that my attachments have been fully loaded prior to starting the parallel for each?
Solutions in C# are more than welcome.
Thank you in advance
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