Thread Pool : ThreadPool « Thread « VB.Net Tutorial

1. VB.Net Tutorial
2. Thread
3. ThreadPool

Imports System.Threading

Module Module1

    Sub TaskA(ByVal state As Object)
        Dim I As Integer

        For I = 0 To 250
            System.Console.Write("A")
        Next

        Thread.Sleep(3000)

        CType(state, AutoResetEvent).Set()
    End Sub

    Sub TaskB(ByVal state As Object)
        Dim I As Integer

        For I = 0 To 250
            System.Console.Write("B")
        Next

        Thread.Sleep(3000)

        CType(state, AutoResetEvent).Set()
    End Sub

    Sub TaskC(ByVal state As Object)
        Dim I As Integer

        For I = 0 To 250
            System.Console.Write("C")
        Next

        Thread.Sleep(3000)

        CType(state, AutoResetEvent).Set()
    End Sub

    Sub Main()
        Dim AIsDone As New AutoResetEvent(False)
        Dim BIsDone As New AutoResetEvent(False)
        Dim CIsDone As New AutoResetEvent(False)

        ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf TaskA), AIsDone)
        ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf TaskB), BIsDone)
        ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf TaskC), CIsDone)

        Dim ThreadCount, ThreadPorts As Integer

        ThreadPool.GetAvailableThreads(ThreadCount, ThreadPorts)
        Console.WriteLine("Thread pool size {0}", ThreadCount)
        Console.WriteLine("Waiting for asynchronous threads to complete.")

        AIsDone.WaitOne()
        Console.WriteLine("A is done")

        BIsDone.WaitOne()
        Console.WriteLine("B is done")

        CIsDone.WaitOne()
        Console.WriteLine("C is done")

    End Sub

End Module

Thread pool size 25
Waiting for asynchronous threads to complete.
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
BBCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCA is done
B is done
C is done