Question

I have the following script which creates 2 threads as you can see.The thing is I would like this code to be tidy-er and the thread making better (such as a loop) but I haven’t been able to manage to create it.

Now i dim thread1 and thread 2 and have separate functions for both.
I am really new to vb.net so please dont shoot be down.

How would I make a public MaxThreads as integer = 2 (or whatever)
and then be able to
for i as 1 to MaxThreads
‘ what now is in function startthread1
next

Public Class UnCheckedItemReader
    Public ForceStop As Boolean = False ' to force shutdown in case the application is Closed
    Public UnCheckedItems As Integer ' to check and report
    Public QueueList As New Dictionary(Of Integer, Integer) ' this list will contain the addressbook ID and the number of the thread holding it
    Public QueueProcessed As New Dictionary(Of Integer, Integer) ' this will aloow us to update the Clientlistview

    Private ds As New DataSet
    Private da As SqlCeDataAdapter = New SqlCeDataAdapter()
    Private connection As New ConnectionClass
    Private table As String = "uncheckItems"

    'threads section - we have 2 threads
    Dim Thread1 As Threading.Thread
    Dim Thread2 As Threading.Thread

    Public Sub Controller()

        Do While ForceStop = False
            If QueueList.Count < 1 Then
                GetDatabaseSqlClientListUnCheckedItems()
                PopulateQueueList()
                StartThreads()
            End If
            Threading.Thread.Sleep(5000)
            Console.WriteLine("New Round")
        Loop


    End Sub



    Private Sub StartThreads()
        StartThread1()
        StartThread2()
    End Sub

    Private Sub StartThread1()
        Dim DS As New RelianProcess
        DS.id = 5
        DS.ThreadId = 1
        DS.QueueList = QueueList

        AddHandler DS.ShowError, AddressOf ShowErrorThread1
        AddHandler DS.Stopit, AddressOf StopThread1
        Thread1 = New System.Threading.Thread(AddressOf DS.StartTimer)
        Thread1.IsBackground = True

        Try
            Thread1.Start()
        Catch e As ThreadStateException
            Console.WriteLine("Caught: {0}", e.Message)
        Catch ex As Exception
            Console.WriteLine("Caught: {0}", ex.Message)
        End Try
    End Sub

    Private Sub StartThread2()
        Dim DS As New RelianProcess
        DS.id = 5
        DS.ThreadId = 2
        DS.QueueList = QueueList

        AddHandler DS.ShowError, AddressOf ShowErrorThread1
        AddHandler DS.Stopit, AddressOf StopThread1
        Thread2 = New System.Threading.Thread(AddressOf DS.StartTimer)
        Thread2.IsBackground = True

        Try
            Thread2.Start()
        Catch e As ThreadStateException
            Console.WriteLine("Caught: {0}", e.Message)
        Catch ex As Exception
            Console.WriteLine("Caught: {0}", ex.Message)
        End Try
    End Sub




    Private Sub ShowErrorThread1(ByVal e As Exception, ByVal id As Integer)
        Console.Write(e.ToString)
        QueueList.Remove(id)

        Console.Write(vbCrLf + "Removed from Mother queuelist " + CStr(id))
        QueueProcessed.Add(id, CInt(GetCurrentUnixTimestamp()))
        Console.Write(vbCrLf + "Added to processed list " + CStr(id))
    End Sub

    Private Sub ShowErrorThread2(ByVal e As Exception, ByVal id As Integer)
        Console.Write(e.ToString)
        QueueList.Remove(id)

        Console.Write(vbCrLf + "Removed from Mother queuelist " + CStr(id))
        QueueProcessed.Add(id, CInt(GetCurrentUnixTimestamp()))
        Console.Write(vbCrLf + "Added to processed list " + CStr(id))
    End Sub

    Private Sub StopThread1()
        Thread1.Abort()
    End Sub

    Private Sub StopThread2()
        Thread2.Abort()
    End Sub


    Private Sub PopulateQueueList()
        Dim i As Integer = 1
        If ds.Tables(table).Rows.Count > 0 Then
            For Each irow As DataRow In ds.Tables(table).Rows
                Try
                    If QueueList.ContainsKey(CInt(irow(0))) = False Then
                        i = i + 1
                        If i = 3 Then 
                            i = 1
                        End If

                        QueueList.Add(CInt(irow(0)), i)
                        Console.WriteLine(ControlChars.NewLine + "Added item {0} to thread {1}", irow(0), i)

                    End If
                Catch e As Exception
                    Console.WriteLine(ControlChars.NewLine + "Exception Raised. The following error occured : {0}", e.Message)
                End Try
            Next
        End If
    End Sub

Answer 1

Instead of declaring each thread individually, use a Collection of Threads. Something along these lines:

    Dim m_threads As New List(Of Threading.Thread)
Dim m_maxThreads As Int32 = 5

Private Sub StartAllThreads()


    For pos As Int32 = 1 To m_maxThreads
        StartThread(pos)
    Next
End Sub

Private Sub StartThread(p_threadID As Int32)
    Dim tempThread As Threading.Thread
    Dim DS As New RelianProcess


    DS.id = 5
    DS.ThreadId = p_threadID
    DS.QueueList = QueueList

    tempThread = New System.Threading.Thread(AddressOf DS.StartTimer)
    m_threads.Add(tempThread)

    AddHandler DS.ShowError, AddressOf ShowErrorThread1
    AddHandler DS.Stopit, AddressOf StopThread1
    tempThread.IsBackground = True

    Try
        tempThread.Start()
    Catch e As ThreadStateException
        Console.WriteLine("Caught: {0}", e.Message)
    Catch ex As Exception
        Console.WriteLine("Caught: {0}", ex.Message)
    End Try

End Sub