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Old June 10th, 2003, 08:26 AM
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Default Problems with threads. Threads disappearing?

Hello,
I have made an application to send and receive big amounts of XML files from and to a lot of other PC's. All these PC's (workstations) act like an FTP server. So basically I have to put and get all the recent XML files to and from these workstations (these workstations are equipped with Windows XP CE). We have in total about 20 workstations now, but this will evolve to about 150 workstations.
We use the FTP .NET component from DART.
Basically I made a class (called FTPCollection), each class has an Arraylist containing IP addresses to some of the workposts. Every FTPCollection has his own BeginPut and EndPut public method. With BeginPut and Endput we launch a separate thread in which an infinite loop (while not EndRequested) sends or receives the files (and deleting them on server or client side) from every workstation.
So when this collection has e.g. three workstations we first get the files from the first, then from the second, then from the third. Again from the first, then the second, then from the third. And so on... Same thing for sending (put).
After the last workstation has been updated I put the thread to sleep for 10 seconds (to save a bit on network traffic) and write some stuff to a log file.

We have no more than 5 collections running (so basically 10 FTP instances).

Now our problem: it seems that after a time (more than a day) our threads disappear. I don't have exceptions, I'm not notified of the infinite loop being ended (would be logged, but I see nothing).

I'm not a big expert on threading yet (I'm reading about it for the moment, but this thing is bugging us for weeks. Does anyone has an idea?

Thanks,
Dries

Hereunder is the code for the class:

Imports System.Threading
Imports Dart.PowerTCP.Ftp.Ftp

Public Class FTPCollection

#Region "Shared members"
    Private Shared NumberOfProcesses As Integer = 0
#End Region

#Region "Inhereted properties and methods"
    Public Collection As System.Collections.ArrayList
#End Region

#Region "Constructors"
    Public Sub New(ByVal Index As Integer)
        Collection = New System.Collections.ArrayList()
        CollectionIndex = Index
        PutStopped = True
        GetStopped = True
    End Sub
#End Region

#Region "Private EventHandlers"
    Public Event EndPutCollection(ByVal CollectionIndex As Integer)
    Public Event EndGetCollection(ByVal CollectionIndex As Integer)
#End Region

#Region "Private variables"
    Private CollectionIndex As Integer
    Private Put_Thread As Thread
    Private Get_Thread As Thread
    Private FTPGet As Dart.PowerTCP.Ftp.Ftp = New Dart.PowerTCP.Ftp.Ftp()
    Private FTPPut As Dart.PowerTCP.Ftp.Ftp = New Dart.PowerTCP.Ftp.Ftp()
    Private StopGetFlag As Boolean
    Private StopPutFlag As Boolean
    Private PutStopped As Boolean
    Private GetStopped As Boolean
#End Region

#Region "Public methods"
    Public Sub StartPut()
        StopPutFlag = False
        PutStopped = False
        Dim Put_Thread As New Thread(AddressOf Me.PutEntries)
        Put_Thread.Start()
    End Sub

    Public Sub StartGet()
        StopGetFlag = False
        GetStopped = False
        Dim Get_Thread As New Thread(AddressOf Me.GetEntries)
        Get_Thread.Start()
    End Sub

    Public Sub StopPut()
        StopPutFlag = True
    End Sub

    Public Sub StopGet()
        StopGetFlag = True
    End Sub

    Public Function PutFTPStopped() As Boolean
        Return PutStopped
    End Function

    Public Function GetFTPStopped() As Boolean
        Return GetStopped
    End Function
#End Region

#Region "Private methods"
    Private Sub PutEntries()
        Dim myEnumerator As System.Collections.IEnumerator = Collection.GetEnumerator()
        Dim PutCarFiles() As Dart.PowerTCP.Ftp.FtpFile
        Dim PutCarFile As Dart.PowerTCP.Ftp.FtpFile
        Dim EntryID As String

        While Not StopPutFlag 'Only stop this loop when we're changing this flag value
            While myEnumerator.MoveNext() And Not StopPutFlag
                If CType(myEnumerator.Current, HMI_Entry).Online Then 'Only put files via FTP if the remote host is online
                    Try
                        EntryID = CType(myEnumerator.Current, HMI_Entry).HMI_ID.ToString
                        FTPPut = New Dart.PowerTCP.Ftp.Ftp()
                        FTPPut.Server = CType(myEnumerator.Current, HMI_Entry).IP
                        FTPPut.Username = System.Configuration.ConfigurationSettings.AppSett ings("FTPUser")
                        FTPPut.Password = System.Configuration.ConfigurationSettings.AppSett ings("FTPPassword")
                        FTPPut.Timeout = CInt(System.Configuration.ConfigurationSettings.Ap pSettings("FTPEOLTimeOut"))
                        FTPPut.ServerPort = 21
                        FTPPut.FileType = Dart.PowerTCP.Ftp.FileType.Image
                        PutCarFiles = FTPPut.Put(System.Configuration.ConfigurationSetti ngs.AppSettings("Car2HMIPath") & "\" & EntryID & "\", "*.xml", "IP/IN/", False)

                        If Not (PutCarFiles Is Nothing) Then
                            For Each PutCarFile In PutCarFiles
                                frmMain.AddFTPText(EntryID & " - " & PutCarFile.LocalFileName.Substring(PutCarFile.Loca lFileName.LastIndexOf("\") + 1) & " was " & PutCarFile.Status.ToString, frmMainForm.FTPTextDirection.Car2HMI, EntryID)
                                If (PutCarFile.Status = Dart.PowerTCP.Ftp.FtpFileStatus.TransferCompleted And PutCarFile.Exception Is Nothing) Then

                                    'If needed we will backup this file
                                    If CType(System.Configuration.ConfigurationSettings.A ppSettings("BackupCar2HMIFiles"), Boolean) Then
                                        If WaitForExclusiveAccessToFile(PutCarFile.LocalFileN ame) Then
                                            Try
                                                BackupFile(PutCarFile.LocalFileName, System.Configuration.ConfigurationSettings.AppSett ings("Car2HMIBackupPath").ToString & "\" & EntryID, "bak")
                                            Catch BackupEx As Exception
                                                System.IO.File.Delete(PutCarFile.LocalFileName)
                                            Exit Sub
                                            End Try
                                        End If
                                    Else
                                        System.IO.File.Delete(PutCarFile.LocalFileName)
                                    End If
                                End If
                            Next
                            PutCarFile = Nothing
                        End If
                        PutCarFiles = Nothing
                        FTPPut.Close()
                        FTPPut = Nothing
                    Catch ex As System.Net.Sockets.SocketException
                        'FTPHost was unreachable
                        CType(myEnumerator.Current, HMI_Entry).Online = False
                        FTPPut = Nothing
                    Catch ex As Exception
                        FTPPut = Nothing
                        'Unspecified error
                    End Try
                Else
                    WriteFTPPutLog(EntryID & " seems off line", CollectionIndex)
                End If
            End While
            myEnumerator.Reset()

            While myEnumerator.MoveNext And Not StopPutFlag
                If Not CType(myEnumerator.Current, HMI_Entry).Online Then
                    Try
                        If Echo(CType(myEnumerator.Current, HMI_Entry).IP) Then
                            CType(myEnumerator.Current, HMI_Entry).Online = True
                            'WriteFTPPutLog("Ping to: " & CType(myEnumerator.Current, HMI_Entry).IP.ToString & " was a success!", CollectionIndex)
                        Else
                            'WriteFTPPutLog("Ping to: " & CType(myEnumerator.Current, HMI_Entry).IP.ToString & " failed!", CollectionIndex)
                        End If
                    Catch ex As Exception
                        'WriteFTPErrorLog(CollectionIndex, " Algemene exception tijdens het pingen van: " & EntryID & ": " & ex.ToString & ex.Message.ToString, False)
                    End Try
                End If
            End While
            myEnumerator.Reset()

            WriteFTPErrorLog(CollectionIndex, "gaat in de sleep", False)
            System.Threading.Thread.CurrentThread.Sleep(CInt(S ystem.Configuration.ConfigurationSettings.AppSetti ngs("FTPSendTimerInterval")))
            WriteFTPErrorLog(CollectionIndex, "uit de sleep", False)

        End While
        PutStopped = True 'If we get here, it means we stopped PUT files
    End Sub

    Private Sub GetEntries()
        Dim myEnumerator As System.Collections.IEnumerator = Collection.GetEnumerator()
        Dim GetCarFiles() As Dart.PowerTCP.Ftp.FtpFile
        Dim GetCarFile As Dart.PowerTCP.Ftp.FtpFile
        Dim EntryID As String

        While Not StopGetFlag 'Only stop this loop when we're changing this flag value
            While myEnumerator.MoveNext() And Not StopGetFlag
                If CType(myEnumerator.Current, HMI_Entry).Online Then 'Only put files via FTP if the remote host is online
                    Try
                        EntryID = CType(myEnumerator.Current, HMI_Entry).HMI_ID.ToString
                        FTPGet = New Dart.PowerTCP.Ftp.Ftp()
                        While FTPGet.Busy
                            Dim SleepCounter As Integer
                            System.Threading.Thread.Sleep(100)
                            SleepCounter += 1
                            If SleepCounter >= 10 Then
                                'WriteFTPErrorLog(CollectionIndex, "FTPGet closes not fast enough", True)
                                Exit While
                            End If
                        End While

                        FTPGet.Server = CType(myEnumerator.Current, HMI_Entry).IP
                        FTPGet.Username = System.Configuration.ConfigurationSettings.AppSett ings("FTPUser")
                        FTPGet.Password = System.Configuration.ConfigurationSettings.AppSett ings("FTPPassword")
                        FTPGet.Timeout = CInt(System.Configuration.ConfigurationSettings.Ap pSettings("FTPEOLTimeOut"))
                        FTPGet.ServerPort = 21
                        FTPGet.FileType = Dart.PowerTCP.Ftp.FileType.Image

                        GetCarFiles = FTPGet.Get("IP/OUT/", "*.xml", System.Configuration.ConfigurationSettings.AppSett ings("HMI2CarPath") & "\" & EntryID, False)

                        If Not (GetCarFiles Is Nothing) Then
                            For Each GetCarFile In GetCarFiles
                                frmMain.AddFTPText(EntryID & " - " & GetCarFile.LocalFileName.Substring(GetCarFile.Loca lFileName.LastIndexOf("\") + 1) & " was " & GetCarFile.Status.ToString, frmMainForm.FTPTextDirection.HMI2Car, EntryID)
                                If (GetCarFile.Status = Dart.PowerTCP.Ftp.FtpFileStatus.TransferCompleted And GetCarFile.Exception Is Nothing) Then
                                    Try
                                        FTPGet.Delete(GetCarFile.RemoteFileName, True, False)
                                    Catch ex As Exception
                                        'WriteFTPErrorLog(CollectionIndex, "Error during Deleting file from " & EntryID & " " & GetCarFile.LocalFileName, True)
                                    End Try
                                End If
                            Next
                            GetCarFile = Nothing
                        End If
                        GetCarFiles = Nothing
                        FTPGet.Close()
                        FTPGet = Nothing
                    Catch ex As System.Net.Sockets.SocketException
                        FTPGet.Close()
                        FTPGet = Nothing
                        WriteFTPErrorLog(CollectionIndex, "SocketException tijdens het getten van: " & EntryID & ": " & ex.ToString & ex.Message.ToString, True)
                        'FTPHost was unreachable
                        'CType(myEnumerator.Current, HMI_Entry).Online = False
                    Catch ex As Exception
                        WriteFTPErrorLog(CollectionIndex, " Algemene exception tijdens het getten van: " & EntryID & ": " & ex.ToString & ex.Message.ToString & "FtpGet.Busy =" & FTPGet.Busy.ToString, True)
                        FTPGet.Close()
                        FTPGet = Nothing
                        'Unspecified error
                        'WAT HIER DOEN?
                    End Try
                Else
                    'WriteFTPGetLog(EntryID & " seems off line", CollectionIndex)
                End If
            End While
            myEnumerator.Reset()
            'MessageBox.Show("Maak hier mechanisme die de foutieve HMI's gaat pingen")
            WriteFTPErrorLog(CollectionIndex, "gaat in Sleep", True)
            System.Threading.Thread.CurrentThread.Sleep(CInt(S ystem.Configuration.ConfigurationSettings.AppSetti ngs("FTPReceiveTimerInterval")))
            WriteFTPErrorLog(CollectionIndex, "uit de sleep", True)
        End While

        GetStopped = True 'If we get here, it means we stopped GET files
        WriteFTPErrorLog(CollectionIndex, "GetStopped = true. We stoppen de FTPGet van deze collectie. Laatste HMI was : " & EntryID & ":" & GetCarFile.LocalFileName, True)
    End Sub

#End Region
End Class
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