Public Class WorkItem
        ' Die Message
    End Class
 
    Private __closeDown As Boolean
    Private __workQueue As New Queue(Of WorkItem)
    Private __workEvent As New System.Threading.AutoResetEvent(False)
 
    Private Function getWorkItem() As WorkItem
        Dim nextWi As WorkItem = Nothing
        Do
            SyncLock __workQueue
                If __workQueue.Count > 0 Then
                    nextWi = __workQueue.Dequeue()
                End If
            End SyncLock
            If nextWi Is Nothing Then
                __workEvent.WaitOne()
            End If
        Loop While nextWi Is Nothing And Not __closeDown
        Return nextWi
    End Function 'getWorkItem() 
 
    Public Sub PostWorkItem(ByVal wi As WorkItem)
        SyncLock __workQueue
            __workQueue.Enqueue(wi)
            If __workQueue.Count = 1 Then
                ' Post (maybe) waiting work thread 
                __workEvent.Set()
            End If
        End SyncLock
    End Sub 'PostWorkItem()

Those people who think they know everything are a great annoyance to those of us who do - Isaac Asimov