Threading in Visual Studio 2008 - They disappear and don't come back!

• • Reply

  11 years ago

  by dazzle

  Dale Morrell

  , Australia

  Joined 12 years ago

  I am using the following code which works OK in a single thread as shown below, however, when I try to load the datatables asynchonously (by commenting out the synchonous and commenting in the asynchronous in FillDataSet) the first thread never comes back. I know by steping that it gets as far as filling the datatable in GetJobs but after that it dissapears. Does anyone know why?

  BTW the data link is SLOW - it takes close to a minute to fill the tables (137 & ~100 rows) when the form loads synchonously. I was hoping that an asynchronous approach would speed up the app initilisation but so far it doesn't work and I'd rather have a slow app that works than a fast one that doesn't

      Imports System.ComponentModel
  
      Public Class FormJobNumber
          Private pJobsLoaded As Boolean = True
          Private pPurchasesLoaded As Boolean = True
  
          Public ReadOnly Property JobsLoaded() As Boolean
              Get
                  Return pJobsLoaded
              End Get
          End Property
  
          Public ReadOnly Property PurchasesLoaded() As Boolean
              Get
                  Return pPurchasesLoaded
              End Get
          End Property
  
          Public Sub FillDataSet(ByVal SupplierInfo As Supplier)
              GetJobs(Nothing, Nothing)
              GetSuppliers(SupplierInfo, Nothing, Nothing)
              'BackgroundWorkerJobs.RunWorkerAsync()
              'BackgroundWorkerSuppliers.RunWorkerAsync(SupplierInfo)
          End Sub
  
          Private Function GetJobs(ByVal worker As BackgroundWorker, ByVal e As DoWorkEventArgs) As Integer
              Try
                  Return Me.JobsDataAdapter.Fill(Me.Myob1.Jobs)
              Catch ex As Exception
                  MsgBox("Error: " & ex.Message & vbCrLf & "Getting Jobs from MYOB", MsgBoxStyle.Critical, "Error")
                  Me.DialogResult = System.Windows.Forms.DialogResult.Cancel
                  Me.Hide()
                  Return -1
              End Try
          End Function
  
          Private Function GetSuppliers(ByVal SupplierInfo As Supplier, ByVal worker As BackgroundWorker, ByVal e As DoWorkEventArgs) As Integer
              Try
                  Me.PurchasesDataAdapter.SelectCommand.Parameters("SupplierName").Value = SupplierInfo.FullName
                  Me.PurchasesDataAdapter.SelectCommand.Parameters("StartDate").Value = Now.AddMonths(-1).AddDays(-Now.Day).ToString("MM/dd/yyyy")
                  Return Me.PurchasesDataAdapter.Fill(Me.Myob1.Purchases)
              Catch ex As Exception
                  MsgBox("Error: " & ex.Message & vbCrLf & "Getting Jobs from MYOB", MsgBoxStyle.Critical, "Error")
                  Me.DialogResult = System.Windows.Forms.DialogResult.Cancel
                  Me.Hide()
                  Return -1
              End Try
          End Function
  
          Private Sub BackgroundWorkerJobs_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorkerJobs.DoWork
              Dim worker As BackgroundWorker = CType(sender, BackgroundWorker)
              pJobsLoaded = False
              e.Result = GetJobs(worker, e)
          End Sub
  
          Private Sub BackgroundWorkerJobs_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorkerJobs.RunWorkerCompleted
              pJobsLoaded = True
          End Sub
  
          Private Sub BackgroundWorkerSuppliers_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorkerSuppliers.DoWork
              Dim worker As BackgroundWorker = CType(sender, BackgroundWorker)
              pPurchasesLoaded = False
              While Not Me.JobsLoaded
              End While
              e.Result = GetSuppliers(e.Argument, worker, e)
          End Sub
  
          Private Sub BackgroundWorkerSuppliers_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorkerSuppliers.RunWorkerCompleted
              pPurchasesLoaded = True
          End Sub
      End Class
  

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