Multithreading Race Conditions

[cmdolcet69]

Im having an issue setting back my databackgroundw orker.is busy to
false. I call the CancelAsync() however it doesn;t cancel anything
with the backgroundworke r.

What else can I do. I can;t set the .Isbusy because its read-only



Public Sub StopAllDataBack groundThreads()
Me.tmrBackgroun dWorker.Enabled = False
Me.tmrBackgroun dWorker2.Enable d = False

If Not IsNothing(Me.da taBackgroundWor ker) Then
If dataBackgroundW orker.IsBusy Then
Me.dataBackgrou ndWorker.Cancel Async()
While dataBackgroundW orker.IsBusy
Application.DoE vents()
Me.dataBackgrou ndWorker.Cancel Async()
End While
Me.dataBackgrou ndWorker.Dispos e()
End If
End If

If Not IsNothing(Me.da taBackgroundWor ker2) Then
If dataBackgroundW orker2.IsBusy Then
Me.dataBackgrou ndWorker2.Cance lAsync()
While dataBackgroundW orker2.IsBusy
Application.DoE vents()
Me.dataBackgrou ndWorker2.Cance lAsync()
End While
Me.dataBackgrou ndWorker2.Dispo se()
End If
End If
End Sub

[Armin Zingler]

Re: Multithreading Race Conditions

"cmdolcet69 " <colin_dolcetti @hotmail.comsch rieb

Im having an issue setting back my databackgroundw orker.is busy to
false. I call the CancelAsync() however it doesn;t cancel anything
with the backgroundworke r.
>
What else can I do. I can;t set the .Isbusy because its read-only
>
>
>
Public Sub StopAllDataBack groundThreads()
Me.tmrBackgroun dWorker.Enabled = False
Me.tmrBackgroun dWorker2.Enable d = False
>
If Not IsNothing(Me.da taBackgroundWor ker) Then
If dataBackgroundW orker.IsBusy Then
Me.dataBackgrou ndWorker.Cancel Async()
While dataBackgroundW orker.IsBusy
Application.DoE vents()
Me.dataBackgrou ndWorker.Cancel Async()
End While

Read the first two paragraphs in the Remarks section:
http://msdn.microsoft.com/en-us/libr...ncelasync.aspx


Does your backgroundworke r check the CancellationPen ding property? If not,
you have to add it and exit the method(s) if it is True.


Armin

[cmdolcet69]

Re: Multithreading Race Conditions

On Oct 31, 3:21 pm, "Armin Zingler" <az.nos...@free net.dewrote:

"cmdolcet69 " <colin_dolce... @hotmail.comsch rieb
>
>
>

Im having an issue setting back my databackgroundw orker.is busy to
false. I call the CancelAsync() however it doesn;t cancel anything
with the backgroundworke r.

>

What else can I do. I can;t set the .Isbusy because its read-only

>

Public Sub StopAllDataBack groundThreads()
       Me.tmrBackgroun dWorker.Enabled = False
       Me.tmrBackgroun dWorker2.Enable d = False

>

       If Not IsNothing(Me.da taBackgroundWor ker) Then
           If dataBackgroundW orker.IsBusy Then
               Me.dataBackgrou ndWorker.Cancel Async()
               While dataBackgroundW orker.IsBusy
                   Application.DoE vents()
                   Me.dataBackgrou ndWorker.Cancel Async()
   End While

>
Read the first two paragraphs in the Remarks section:http://msdn.microsoft.com/en-us/libr...tmodel.backgro...
>
Does your backgroundworke r check the CancellationPen ding property? If not,
you have to add it and exit the method(s) if it is True.
>
Armin

Check what you had asked I see that the .IsBusy property never gets
set back to false its always true. Therefore I dont think
the .CancelAsync() is working? THe collection pending is False

[Mark S. Milley]

Re: Multithreading Race Conditions

There is a property setting that you need to turn on.

I believe it's "SupportsCancel lation", but I'm not sure.

Regards,

-M

[Armin Zingler]

Re: Multithreading Race Conditions

"cmdolcet69 " <colin_dolcetti @hotmail.comsch rieb

Read the first two paragraphs in the Remarks
section:http://msdn.microsoft.com/en-us/libr...tmodel.backgro...
>
Does your backgroundworke r check the CancellationPen ding property? If not,
you have to add it and exit the method(s) if it is True.
>
Armin

Check what you had asked I see that the .IsBusy property never gets
set back to false its always true. Therefore I dont think
the .CancelAsync() is working? THe collection pending is False


==========

I forgot to say that the WorkerSupportsC ancellation property must
also be True. But it seems it is, otherwise you'd get an exception.


Try this in a new project. Works for me:

Imports System.Componen tModel

Public Class Form1

Private Sub Form1_Load( _
ByVal sender As System.Object, ByVal e As System.EventArg s) _
Handles MyBase.Load

Dim bgw As New BackgroundWorke r

bgw.WorkerSuppo rtsCancellation = True
AddHandler bgw.DoWork, AddressOf OnDoWork
AddHandler bgw.RunWorkerCo mpleted, AddressOf OnWorkerComplet ed

Debug.Print("St arting worker")
bgw.RunWorkerAs ync()

Debug.Print("Wa iting 5 seconds...")
Threading.Threa d.Sleep(5000)
Debug.Print("Ca ncelling worker")
bgw.CancelAsync ()

End Sub

Private Sub OnDoWork( _
ByVal sender As Object, _
ByVal e As System.Componen tModel.DoWorkEv entArgs)

Debug.Print("St art OnDoWork")
Do
Threading.Threa d.Sleep(250)
Loop Until DirectCast(send er, BackgroundWorke r).Cancellation Pending
Debug.Print("En d OnDoWork")

End Sub

Private Sub OnWorkerComplet ed( _
ByVal sender As Object, _
ByVal e As System.Componen tModel.RunWorke rCompletedEvent Args)

Debug.Print("Wo rker completed")

End Sub


End Class



Armin