Can someone spot the issue in this background thread implementation?
The docs say, the RunWorkerCompleted must fire irrespective of
exception. It does so on my machine when there is no loop. When the
loop is present, with at least a time delay, the completed event never
fires. Am I missing something?
Imports System.Threading
Public Class Form1
Dim _BackgroundWorkerFinished As Boolean = False
Private WithEvents _BackgroundWorker As New
System.ComponentModel.BackgroundWorker
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e
As System.EventArgs) Handles Button1.Click
_BackgroundWorker.WorkerReportsProgress = True
_BackgroundWorker.RunWorkerAsync()
'uncommented, RunWorkerCompleted never fires on my machine.
'comment these 3 lines and RunWorkerCompleted fires as normal
'Do
' Threading.Thread.Sleep(3000)
'Loop Until _BackgroundWorkerFinished
TextBox1.Text += _BackgroundWorkerFinished.ToString
End Sub
Private Sub _BackgroundWorker_DoWork(ByVal sender As
System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs)
Handles _BackgroundWorker.DoWork
Throw New Exception("Blow up immediately.")
End Sub
Public Shared MonitorLock As Object = New Object()
Private Sub _BackgroundWorker_RunWorkerCompleted(ByVal sender As
Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs)
Handles _BackgroundWorker.RunWorkerCompleted
If (e.Error IsNot Nothing) Then
MessageBox.Show(e.Error.Message)
End If
Monitor.Enter(MonitorLock)
_BackgroundWorkerFinished = True
Monitor.Exit(MonitorLock)
TextBox1.Text = " end of run Completed "
End Sub
End Class
