background worker e semafori

[giuseppe500]

ciao.
Ho due background worker uno che si deve attivare ogni 10 sec e uno ogni 50 sec.
e devosincronizzarli , ho pensato di usare un semaforo , dichiarato come shared(vb.net) in un wrapper attorno al background worker.
posto subito il codice un po semplificato:

'Background worker ogni 10 sec
Public Class BWSpooler
  Dim bw As BackgroundWorker = New BackgroundWorker
  Public Sub New()
    bw.WorkerSupportsCancellation = True
    bw.WorkerReportsProgress = True
    AddHandler bw.DoWork, AddressOf DoWork
    'AddHandler bw.ProgressChanged, AddressOf bw_ProgressChanged
    AddHandler bw.RunWorkerCompleted, AddressOf bw_RunWorkerCompleted

  End Sub

  Private Sub DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)
    Try
      Dim worker As BackgroundWorker = CType(sender, BackgroundWorker)
      Dim i As Integer

      For i = 1 To 10
        If bw.CancellationPending = True Then
          e.Cancel = True
          Exit For

        Else

          Threading.Thread.Sleep(10000)

          BWScheduler.mainCount += 1

          Try
            BWScheduler.semap.Release()
          Catch

          End Try
end sub
end class

e il primo ogni 50 sec:

Public Class BWScheduler
  Dim bw As BackgroundWorker = New BackgroundWorker
  Public Shared semap As New System.Threading.Semaphore(0, 1)
  Public Shared releaseCount As Integer = 0
  Public Shared mainCount As Integer = 0
  Private n As Integer = 0
  Public Sub New()

    AddHandler bw.DoWork, AddressOf bw_DoWork
    'AddHandler bw.ProgressChanged, AddressOf bw_ProgressChanged
    AddHandler bw.RunWorkerCompleted, AddressOf bw_RunWorkerCompleted

  End Sub

  Private Sub bw_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)
    Try

      Dim worker As BackgroundWorker = CType(sender, BackgroundWorker)
      Dim i As Integer

      For i = 1 To 10
        If bw.CancellationPending = True Then
          e.Cancel = True

          Exit For
        Else
          BWScheduler.semap.WaitOne()
          ' Perform a time consuming operation and report progress.
          System.Threading.Thread.Sleep(50000)
          BWScheduler.releaseCount += 1
next
end sub
end class

ora , ho provato col try catch nel

          Try
            BWScheduler.semap.Release()
          Catch

          End Try

e dopo la prima volta mi da un errore , ho provato a mettere nel catch un BWScheduler.semap.WaitOne() ma dopo mi si interrompe il thread.

ho tntato di fare questo per sincronizzare i due background worker.
Ho anche provato a mettere in ciascun backround worker un BWScheduler.semap.WaitOne() all'inizio e un release alla fine ma cosi devo aspettare il bw piu lento e non funziona come vorrei .

ps. voglio sincronizzare pperchè i due bw nell'applicazione reale lavorano sulle stesse risorse e non voglio sovrapposizioni o casini di ogni genere
grazie.