vb.net simple Parallel & Thread example

Imports System.Threading Imports System.Threading.Tasks Public Class Form1 ' Private Queue1 As New Queue(Of String()) Private cts As New CancellationTokenSource() Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Btn1.Click If Btn1.Text.Contains("Start") Then QueueList.Add(New Queue(Of String())) Dim P_W As WaitCallback = New WaitCallback(AddressOf producer) Dim C_W1 As WaitCallback = New WaitCallback(AddressOf consumer) Dim C_W2 As WaitCallback = New WaitCallback(AddressOf consumer) Dim M_W As WaitCallback = New WaitCallback(AddressOf Monitor2) ThreadPool.QueueUserWorkItem(P_W, cts.Token) ThreadPool.QueueUserWorkItem(C_W1, cts.Token) ThreadPool.QueueUserWorkItem(C_W2, cts.Token) ThreadPool.QueueUserWorkItem(M_W, cts.Token) Btn1.Text = "Thread Stop" Else cts.Cancel() Btn1.Text = "Thread Start" End If End Sub Private QueueList As New List(Of Queue(Of String())) Sub producer(ByVal arg As Object) Dim token As CancellationToken = CType(arg, CancellationToken) Dim Array(50) As String While 1 = 1 If token.IsCancellationRequested Then Exit While Else 'Monitor.Enter(QueueList) If QueueList.Count = 0 Then QueueList.Add(New Queue(Of String())) QueueList(QueueList.Count - 1).Enqueue(Array) ElseIf QueueList(QueueList.Count - 1).Count < 500 Then QueueList(QueueList.Count - 1).Enqueue(Array) Else QueueList.Add(New Queue(Of String())) QueueList(QueueList.Count - 1).Enqueue(Array) End If 'Monitor.Exit(QueueList) Thread.Sleep(1) End If End While End Sub Sub consumer(ByVal arg As Object) Dim token As CancellationToken = CType(arg, CancellationToken) While 1 = 1 If token.IsCancellationRequested Then Exit While Else Monitor.Enter(QueueList) If QueueList.Count > 0 AndAlso QueueList(0).Count = 500 Then Parallel.ForEach(QueueList(0), Sub(Data) InsertData(Data) End Sub) QueueList.Remove(QueueList(0)) End If Monitor.Exit(QueueList) End If End While End Sub Private Sub InsertData(Data As String()) 'Work Thread.Sleep(5) End Sub Sub Monitor2(ByVal arg As Object) Dim token As CancellationToken = CType(arg, CancellationToken) While True If token.IsCancellationRequested Then Exit While Else Monitoring(1) Thread.Sleep(50) End If End While End Sub Private Delegate Sub AppendTextBoxDelegate(ByVal ThreadNum As Integer) Private Sub Monitoring(ThreadNum As Integer) If ThreadNum = 1 Then If Txt1.InvokeRequired Then Txt1.Invoke(New AppendTextBoxDelegate(AddressOf Monitoring), New Object() {ThreadNum}) Else Dim TotalCount As Integer = 0 For Each que As Queue(Of String()) In QueueList TotalCount += que.Count Next Txt1.Text = TotalCount End If End If End Sub End Class