Start New Thread As Soon As Previously Thread Gets Finished?

Jul 23, 2010

i have to develop windows service which will copy files to different servers.So i have to do this task using multi-theading.But i have to start only 3-4 threads.So whenever one threads get finished then i have to start new thread so that count of thread should remain 3 or 4

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Use WebBrowser Object In Thread's Operation (start Thread)

Jun 11, 2009

i want to have some web browsers which navigate wile the thread is running and my problem is that I want to use a web browser object from .net in a thread. when i put a webbrowser object in my form, called webbrowser1, i cant reach it in the thread's operation(start thread). when i type webbroeser1 in the thread it doesn't undrestand what webbrowser1 is.

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VS 2010 Error - Cross-Thread Operation Not Valid: Control TbPlaca1 Accessed From A Thread Other Than The Thread It Was Created On

Aug 13, 2010

In one application, I need use 4 simultaneous threads.When the threads finished, I need to update the text of a TextBox.So, I create 4 Textbox, and I wanna the threads change the text to FINISHED.Each thread change one distinct TB.I use this "example"

Dim Terminados As Integer = 0
Private Sub frmEnviarMensagem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Enabled = True
Timer1.Start()

[code]....

The problem is, I have an error in the red lines.The error is: INVALIDOPERATIONEXCEPTION "Cross-Thread operation not valid: Control tbPlaca1 Accessed from a thread other than the thread it was created on."I don't use cross threading. Each TB only was accessed for the correspondent thread, and for the "main program".

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Cross-thread Operation Not Valid: Control 'Panel1' Accessed From A Thread Other Than The Thread It Was Created On." ?

Nov 3, 2011

This is the error message I am getting:

"Cross-thread operation not valid: Control 'Panel1' accessed from a thread other than the thread it was created on." The reason I am getting this error is because I am opening up a new form and then calling these three things:

Panel1.Show()
Label1.Show()
Label2.Show()

why I get this error message because it doesn't occur normally if I open Form2 after closing Form1, it only occurs when I open Form2 after closing Form4.

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Error - Cross-thread Operation Not Valid: Control 'txt1' Accessed From A Thread Other Than The Thread It Was Created On

Jul 21, 2009

I have done a program using vb2005 to display reading from my microcontroller bs2 board but have encountered some problems. My code are as follows.

Dim Stop_Rx As Boolean
Private Sub btnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRead.Click
SerialPort1.Open()

[code]....

I've encounter an error which is, (Cross-thread operation not valid: Control 'txt1' accessed from a thread other than the thread it was created on.)

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Error : Cross-thread Operation Not Valid: Control 'l_users' Accessed From A Thread Other Than The Thread It Was Created On

Jun 21, 2012

When my client try to connect to server I'm getting this error : Cross-thread operation not valid: Control 'l_users' accessed from a thread other than the thread it was created on.

Private Sub _socketManager_onConnectionAccept(ByVal SocketID As String) Handles _socketManager.onConnectionAccept
l_Users.Items.Add(SocketID)
End Sub

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Threading Progress Bar In .net - Thread Operation Not Valid Control 'ProgressBar1' Accessed From A Thread Other Than The Thread It Was Created On

Feb 17, 2012

Would anyone be able to help me here please. I'm fairly new to VB.net and threading so im just trying to figure out what is happening.When I debug this I am getting the error thread operation not valid: Control 'ProgressBar1' accessed from a thread other than the thread it was created on.

I'm a little lost as to why the error is occuring or how to fix it. I've had to put the progress bar in a separate thread otherwise the GUI crashes

[Code]...

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Waiting For Threads - Thread.join Suspend Execution Of Code On Calling Thread Until Spawned Thread Finishes Or Is Aborted

Sep 2, 2010

My understanding is that thread.join will suspend the execution of code on the calling thread until the spawned thread finishes or is aborted...

With that in mind, I tried this:

For i = 1 to 50
threads = New Thread(AddressOf test)
threads.IsBackground = True
threads.SetApartmentState(ApartmentState.STA)

[CODE]...

However, the rest of the code runs when the loop finishes, not waiting for all the spawned threads to finish. Since the rest of the code needs the threads to finish (otherwise the rest will error).

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Cross-thread Operation Not Valid: Control 'Autocad' Accessed From A Thread Other Than The Thread It Was Created On

Jun 6, 2010

I have written an application that loads a form - frmCad as well as AutoCad. It does this via a class which detects when AutoCad quits.

Friend Class CadApp Private WithEvents AppObject As AcadApplication... Private Sub AppObject_BeginQuit(ByRef Cancel As Boolean) Handles AppObject.BeginQuit RaiseEvent Quit() End SubEnd Class

My main class loads frmCad as well as CadApp.

Public Class Cad Private WithEvents frmCad As CadForm Private WithEvents app As CadApp... Public Sub ShowForm() If frmCad Is Nothing Then frmCad = New CadForm frmCad.Visible = True End Sub... Private Sub app_Quit() Handles app.Quit frmCad.Dispose() frmCad = Nothing .... End Sub

When I debug the program, it stops at frmCad.Dispose()The program continues to execute, but all the code after it fails to work.Looking more carefully I get an error message which contains:-Cross-thread operation not valid: Control 'Autocad' accessed from a thread other than the thread it was created on.

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Cross-thread Operation Not Valid: Control 'label2' Accessed From A Thread Other Than The Thread It Was Created On?

Feb 9, 2011

My error:Cross-thread operation not valid: Control 'label2' accessed from a thread other than the thread it was created on. I want to be able to give my Public RunBot() sub access to edit Labels, buttons, etc without an error.

[Code]...

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Cross-thread Operation Not Valid: Control 'lblStatus' Accessed From A Thread Other Than The Thread It Was Created On

Apr 1, 2010

I'm getting the 'System.InvalidOperationException' error on acccessing a thread from other than where it was created. My code is:

'Required by the Windows Form Designer
Public components As System.ComponentModel.IContainer ' changed from private

[code]....

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Cross-thread Operation Not Valid: Control 'statusHO' Accessed From A Thread Other Than The Thread It Was Created On

Jun 6, 2009

My problem is Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on.

System.InvalidOperationException was unhandled
Message="Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on."
Source="System.Windows.Forms"
StackTrace:

[Code]...

i used it and it works fine then. but as it is mentioned its not a good practice to use it. So what should i do? is it ok if i use this as i am not able to use correct practice. Mine application is not for enterprise purpose. its just my class project, and it works fine even if i put application working in background. System works ok. I dont know how to correct this error.As i dont have that much knowlege of threads.

So please guide me how to fix this in correct way otherwise i am force to go for bad programming practice
Please refer to Windows Mobile Developer Center > Smart Device Development Forums > Windows Mobile Development > Appendtext not working for all my code details

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Cross-thread Operation Not Valid: Control 'lv1' Accessed From A Thread Other Than The Thread It Was Created On?

Aug 4, 2009

Cross-thread operation not valid: Control 'lv1' accessed from a thread other than the thread it was created on.

Dim lvi As ListViewItem
For Each lvi In lv1.Items

[code]....

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Error Saying "Cross-thread Operation Not Valid: Control 'lblOnline' Accessed From A Thread Other Than The Thread It Was Created On."?

Feb 7, 2011

Ok i have a Form with the following

Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
txtNotepad.Text = LoadFile("notes.txt")

[code].....

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.net - Why Cancelling 6 WebRequest Using Task.Start Takes Longer That Thread.Start

Jul 24, 2011

I have custom asynchronous WebRequest class that I am testing to find out how fast the request will be cancelled and found some odd results, that starting 6 WebRequests with TPL and cancelling them right away takes 25 sec, but when I used just regular background threads it took only 5 sec.

Update: Running them without cancelling takes with Task.Start 9 sec and Thread.Start 3 sec accordingly.
Imports System.Net
Imports System.Threading

[Code]....

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"Cross-thread Operation Not Valid: Control 'TextBox1' Accessed From A Thread?

Sep 18, 2009

When i run the program i am getting the following error in this line TextBox1.Text &= "File Created: " & FullPath & vbCrLf"Cross-thread operation not valid: Control 'TextBox1' accessed from a thread other than the thread it was created on."

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Write In Worker Thread In A Data Table And Rich Text Box in Main Thread

Mar 4, 2009

I'm creating a Client Server application which involves theServer running some scripts in clients and getting back results in an automated way. In Server, other than Main thread, i have 2 worker threads, a) one monitoring response from clients and b) the other scheduling next available job to respective client which executes that job. The issue here is ,I want these worker threads to write the status of their work in the UI(which comes under Main Thread). Also i need to write things in worker thread in a Data table and Rich Text Box in Main thread. But, I can't do so, since it has been blocked to access one thread's function or property directly from others. Is there any work around to do this?

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Creating A Progress Bar That Runs On Another Thread While Keeping Calculation In Main Thread

Nov 12, 2009

Preface: I know this is an unusual/improper way to do this. I can do this with a "real" ShowDialog(), background worker/thread, and so on. I am trying to do specifically what I describe here, even if it is ugly. If this is impossible for X reason, I have created a fancy progress dialog for some of our long running operations. I need to have this dialog shown on a new thread while having processing continue on the calling (UI in most cases) thread.

[Code]...

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Cross-thread Operation Not Valid Control 'FormSplash' Accessed From A Thread Other?

Sep 5, 2009

I need your help on the following. In debugging mode only the program is stopping to the following line "My.Forms.FormMain.HelpProviderMain.HelpNamespace = "Reports.chm"" with the following error ""An error occurred creating the form. See Exception.InnerException for details. The error is: Cross-thread operation not valid: Control 'FormSplash' accessed from a thread other than the thread it was created on.""

I noticed that when I am putting NONE in SPLASH screen option in the properties of the project, there is no problem.I am no familiar with treating that's why can you give me detail instruction how to overcome this annoying problem?

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Cross-thread Operation Not Valid Exception In Single Thread Application?

Nov 14, 2009

I am getting this exception: Cross-thread operation not valid: Control 'TextBoxOutput' accessed from a thread other than the thread it was created on. in a VB 2008 Windows Forms application that I havent specifically made multi-threaded. I have create a sub called Out() like this:

Private Sub Out(ByVal inString As String)
Me.TextBoxOutput.Text += (Me.TextBoxOutput.Text & inString & vbNewLine)
Me.TextBoxOutput.SelectionStart = Me.TextBoxOutput.Text.Length
Me.TextBoxOutput.ScrollToCaret()
End Sub

and I call it from various events to log messages I am getting from my pbx, which I use a third party open source dll to access. The interesting thing to me is that if I run the deployed application (ie, not in the VS IDE) I do not get any exceptions, it's only from within the IDE.if I add the line: Control.CheckForIllegalCrossThreadCalls = False to the form's constructor, the exceptions stop, but a) this seems like a hacky way to get around the issue and b) the application seems to hang sometimes when I have it set this way.

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Cross-thread Operation Not Valid: Control 'FormSplash' Accessed From A Thread Other

Sep 5, 2009

In debugging mode only the program is stopping to the following line "My.Forms.FormMain.HelpProviderMain.HelpNamespace = "Reports.chm""
with the following error ""An error occurred creating the form. See Exception.InnerException for details. The error is: Cross-thread operation not valid: Control 'FormSplash' accessed from a thread other than the thread it was created on.""I noticed that when I am putting NONE in SPLASH screen option in the properties of the project, there is no problem.

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Cross-thread Operation Not Valid: Control 'hiddenrtb2' Accessed From A Thread

Mar 10, 2010

im getting this error and i cant figure it out.

Public Sub mlogin()
Invoke(chkb, New Object() {"disable"})
Invoke(d, New Object() {achidrtb, "", "="})
Invoke(d, New Object() {hiddenrtb2, "", "="})

[code]....

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Call A Method That Started On A Background Thread On The UI Thread Calling BeginInvoke And Passing In A Delegate?

Aug 27, 2011

I am trying to call a method that started on a background thread on the UI thread calling BeginInvoke and passing in a delegate as follows:

Dispatcher.BeginInvoke(Function() UpdateApplicationDataUI())

to call this method:

Private Sub UpdateApplicationDataUI()
...
End Sub

However, I get an error in the call to BeginInvoke (the UpdateApplicationDataUI portion of the delegate is stating "Expression does not produce a value").

Me.Dispatcher.BeginInvoke(Function() New Action(AddressOf UpdateApplicationDataUI))

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Does Changing Forms Start A New Thread

Feb 17, 2012

I have a basic form which call functions on a numbers of different forms up to (30), Do these functions run in parrallel, or are they run sequentually.Each function as present calls for disk access, if the threads are running in series, this will present a considrable relay, this is not acceptable.

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Start New Thread Adds 4-6 Handles?

Nov 16, 2011

Check process handle count:In Task manager, View, Select columns, mark Handle Count to the view.(The process when loaded has about 333 handles)

Operation:The new thread is set equal to an existing thread, then the existing thread is started and aborted. How does one restore the old handle count? Why do the handles increase by a random number and do not revert?

How can Idisposable/CloseHandle/or GC.collect, Finalize() work in this situation? I'm trying to return the handles to their original count, 333, when I start a new thread it adds 4,5, or 6 handles per new thread(even if the thread is aborted and set to nothing).

[Code]...

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Start The Thread To Load Resultset?

Jun 7, 2010

Could anybody tell me which event is good to start the thread to load resultset?

Example :
Dim Table As DataTable
Sub LoadItem
Dim BL As New BLItem
BL.LoadResultSet()

[Code]...

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Thread Not Start When Click On Button

Mar 16, 2011

I am new with threads in vb.net. I write the following code i use imports system.threading
declare thread as dim read as thread Then on a start btn click i write the following code

[Code]...

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BackgroundWorker Thread Communicate With The Primary UI Thread When Encapsulated In A Class?

Jul 1, 2010

A BackgroundWorker thread can pass data to the primary thread. It does it via the RunWorkerCompleted and ProgressChanged events, which I believe run in the primary thread. I would like to encapsulate the BackgroundWorker control in a class so that I can instantiate it more than once. But I don't know how the BGW can then communicate with the primary thread. If the BGW control is within a class, it does not have access to the properties outside the class. In that case, how can the BGW pass data to the thread that instantiated it?

[Code]....

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Current Thread Must Be Set To Single Thread Apartment Sta Mode Before Ole Calls Can B

Apr 21, 2010

I'm getting the following error:"Current thread must be set to single thread apartment sta mode before ole calls can be made"

I am using Speech.Recognition.SpeechRecognizer and using it to open various dialog boxes. It works fine for the first few but on the third one when it calls the InitializeComponent in the Dialog's New, it throws the above error.

Anybody have any clue what causes this or how to fix it? The SpeechRecognizer seems to run on its own thread, so that seems to be at the root of the problem. If I open thedialog with a button click I don't get an error.

[Code]...

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Error - An Attempt Has Been Made To Free An RCW That Is In Use. The RCW Is In Use On The Active Thread Or Another Thread

Jun 6, 2011

I am in a trouble with this error:"An attempt has been made to free an RCW that is in use. The RCW is in use on the active thread or another thread. Attempting to free an in-use RCW can cause corruption or data loss." I am not sure if the RCW-error is related to my problem but I was having this error last January 25. It appears when I am ending my application. I ignored it. The next morning when I resumed coding for my application, the changes I am making does not appear at run-time anymore. Whatever GUI changes I make in my application (at design time), it does not make any effect any longer when I am running the application. What is causing this? I am so afraid if I have to restart my application from the scratch. I have gone far.

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