VB.NET Monitor類代碼示例

' 導入命名空間
Imports System.Collections.Generic
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim tasks As New List(Of Task)()
      Dim rnd As New Random()
      Dim total As Long = 0
      Dim n As Integer = 0

      For taskCtr As Integer = 0 To 9
         tasks.Add(Task.Run( Sub()
                                Dim values(9999) As Integer
                                Dim taskTotal As Integer = 0
                                Dim taskN As Integer = 0
                                Dim ctr As Integer = 0
                                Monitor.Enter(rnd)
                                   ' Generate 10,000 random integers.
                                    For ctr = 0 To 9999
                                       values(ctr) = rnd.Next(0, 1001)
                                    Next
                                Monitor.Exit(rnd)
                                taskN = ctr
                                For Each value in values
                                   taskTotal += value
                                Next
                                    
                                Console.WriteLine("Mean for task {0,2}: {1:N2} (N={2:N0})",
                                                  Task.CurrentId, taskTotal/taskN,
                                                  taskN)
                                Interlocked.Add(n, taskN)
                                Interlocked.Add(total, taskTotal)
                             End Sub ))
      Next
      
      Try
         Task.WaitAll(tasks.ToArray())
         Console.WriteLine()
         Console.WriteLine("Mean for all tasks: {0:N2} (N={1:N0})",
                           (total * 1.0)/n, n)
      Catch e As AggregateException
         For Each ie In e.InnerExceptions
            Console.WriteLine("{0}: {1}", ie.GetType().Name, ie.Message)
         Next
      End Try
   End Sub
End Module

' 導入命名空間
Imports System.Threading

Friend Class SyncResource
    ' Use a monitor to enforce synchronization.
    Public Sub Access()
        SyncLock Me
            Console.WriteLine("Starting synchronized resource access on thread #{0}",
                              Thread.CurrentThread.ManagedThreadId)
            If Thread.CurrentThread.ManagedThreadId Mod 2 = 0 Then
                Thread.Sleep(2000)
            End If
            Thread.Sleep(200)
            Console.WriteLine("Stopping synchronized resource access on thread #{0}",
                              Thread.CurrentThread.ManagedThreadId)
        End SyncLock
    End Sub
End Class

Friend Class UnSyncResource
    ' Do not enforce synchronization.
    Public Sub Access()
        Console.WriteLine("Starting unsynchronized resource access on Thread #{0}",
                          Thread.CurrentThread.ManagedThreadId)
        If Thread.CurrentThread.ManagedThreadId Mod 2 = 0 Then
            Thread.Sleep(2000)
        End If
        Thread.Sleep(200)
        Console.WriteLine("Stopping unsynchronized resource access on thread #{0}",
                          Thread.CurrentThread.ManagedThreadId)
    End Sub
End Class

Public Module App
    Private numOps As Integer
    Private opsAreDone As New AutoResetEvent(False)
    Private SyncRes As New SyncResource()
    Private UnSyncRes As New UnSyncResource()

    Public Sub Main()
        ' Set the number of synchronized calls.
        numOps = 5
        For ctr As Integer = 0 To 4
            ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf SyncUpdateResource))
        Next
        ' Wait until this WaitHandle is signaled.
        opsAreDone.WaitOne()
        Console.WriteLine(vbTab + vbNewLine + "All synchronized operations have completed.")
        Console.WriteLine()

        numOps = 5
        ' Reset the count for unsynchronized calls.
        For ctr As Integer = 0 To 4
            ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf UnSyncUpdateResource))
        Next

        ' Wait until this WaitHandle is signaled.
        opsAreDone.WaitOne()
        Console.WriteLine(vbTab + vbNewLine + "All unsynchronized thread operations have completed.")
    End Sub

    Sub SyncUpdateResource()
        ' Call the internal synchronized method.
        SyncRes.Access()

        ' Ensure that only one thread can decrement the counter at a time.
        If Interlocked.Decrement(numOps) = 0 Then
            ' Announce to Main that in fact all thread calls are done.
            opsAreDone.Set()
        End If
    End Sub

    Sub UnSyncUpdateResource()
        ' Call the unsynchronized method.
        UnSyncRes.Access()

        ' Ensure that only one thread can decrement the counter at a time.
        If Interlocked.Decrement(numOps) = 0 Then
            ' Announce to Main that in fact all thread calls are done.
            opsAreDone.Set()
        End If
    End Sub
End Module

' 導入命名空間
Imports System.Collections.Generic
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim nTasks As Integer = 0
      Dim tasks As New List(Of Task)()

      Try
         For ctr As Integer = 0 To 9
            tasks.Add(Task.Run( Sub()
                                   ' Instead of doing some work, just sleep.
                                   Thread.Sleep(250)
                                   ' Increment the number of tasks.
                                   Monitor.Enter(nTasks)
                                   Try
                                      nTasks += 1
                                   Finally
                                      Monitor.Exit(nTasks)
                                   End Try
                                End Sub))
         Next
         Task.WaitAll(tasks.ToArray())
         Console.WriteLine("{0} tasks started and executed.", nTasks)
      Catch e As AggregateException
         Dim msg AS String = String.Empty
         For Each ie In e.InnerExceptions
            Console.WriteLine("{0}", ie.GetType().Name)
            If Not msg.Contains(ie.Message) Then
               msg += ie.Message + Environment.NewLine
            End If
         Next
         Console.WriteLine(vbCrLf + "Exception Message(s):")
         Console.WriteLine(msg)
      End Try
   End Sub
End Module

' 導入命名空間
Imports System.Collections.Generic
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim nTasks As Integer = 0
      Dim o As Object = nTasks
      Dim tasks As New List(Of Task)()

      Try
         For ctr As Integer = 0 To 9
            tasks.Add(Task.Run( Sub()
                                   ' Instead of doing some work, just sleep.
                                   Thread.Sleep(250)
                                   ' Increment the number of tasks.
                                   Monitor.Enter(o)
                                   Try
                                      nTasks += 1
                                   Finally
                                      Monitor.Exit(o)
                                   End Try
                                End Sub))
         Next
         Task.WaitAll(tasks.ToArray())
         Console.WriteLine("{0} tasks started and executed.", nTasks)
      Catch e As AggregateException
         Dim msg AS String = String.Empty
         For Each ie In e.InnerExceptions
            Console.WriteLine("{0}", ie.GetType().Name)
            If Not msg.Contains(ie.Message) Then
               msg += ie.Message + Environment.NewLine
            End If
         Next
         Console.WriteLine(vbCrLf + "Exception Message(s):")
         Console.WriteLine(msg)
      End Try
   End Sub
End Module

' Define the lock object.
Dim obj As New Object()

' Define the critical section.
Monitor.Enter(obj)
Try 
   ' Code to execute one thread at a time.

' catch blocks go here.
Finally 
   Monitor.Exit(obj)
End Try

<MethodImplAttribute(MethodImplOptions.Synchronized)>
Sub MethodToLock()
   ' Method implementation.
End Sub