VS 2008 CrossThread Operation - Create A Thread That Load A Function?
Mar 27, 2010
i create a thread that load a function, in this function i need to read from txtbox into the same form and during the function write into another textbox the call to function is done in this way Dim t As Thread t = New Thread(AddressOf Me.myFunction) t.Start() from myFunction i read info in this way myInfo = textbox1.text and i write into textbox during the execution of myFunction in this way textInfo.text = myInfo but in debug time i have an error of crossthread.. how can i solve this problem??
I am using vb.net, and in my program I get this 'crossthread operation not valid' error when I run my backgroundworker that will make this textbox enabled true. My main sub will first turn the enabled to false, and when the backgroundworker runs it will turn it back true then exit. Why does it give me an error? FYI: There is more code to this but I don't want to make it any more confusing... Here is the stack trace:
Got a proccess thread thats in charge of loading a listbox full of the first line of text for richtextbox items on form load. Though I use Me.Invoke(New MethodInvoker...) to add items on the main thread so its thread safe it coughs when the first line of rtf data are thrown at it, acting as if I hadnt called adding the items on the main thread.
Up at the class level: Dim Worker As System.Threading.Thread In the load procedure for the form: Worker = New System.Threading.Thread(AddressOf WorkerDo) Worker.Start()
[Code]....
I"ve also tried to remedy this using a delegate to invoke the listbox before attempting to update it, but the invoke method itself is throwing the exception. I am not using the default instance of the form (a new instance of this form is created). Anyone know how I can get around this? I can't load the listbox full of items directly in the form's load procedure because work takes place in the thread beforehand so there are strings to add to the listbox. I've got MS Visual Studio 2008 Pro and Vista SP2 (latest updates applied).
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".
"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.
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
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
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.
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.
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
This code is from [URL], so I assumed it would have worked, but I am probably missing something simple.
[Code]....
When I run this code, I get an InvalidOperationException (cross thread operation). How can I get my progress bar on the second thread, or does it have to be created at runtime on that thread?
I have a loop the iterate in my ListBox and I got this error. Cross-thread operation not valid: Control 'ListBox1' accessed from a thread other than the thread it was created on.
Here is my codes:
Private Thread As New System.Threading.Thread(AddressOf myFunc) Sub myFunc() Dim i As Integer
[Code]...
My Listbox1 is contain hundreds of lines to loop..thats long iteration. and i need the main form keeps responding from other function even loop is under process. This time i need to use this method of multi-threading.
Im trying to work with threading on a project im doing but i have run into this cross-thread problem, ive worked with background workers before and never had this issue.ive done some searching and found some good threads this one in perticular[URL]..now i tried to use these examples and i made it work on a differant project but i cant seem to get my head around how to make it work on this project.
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."
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?
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.
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.
[Code] If I wanted to add 3 icons, the LV would add them like it normally would, but then, for some reason, it enters the loop again and that's when it throws this error: ex = {"Cross-thread operation not valid: Control 'ListView1' accessed from a thread other than the thread it was created on."}. I don't understand why, because I'm invoking the LV.
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.
Imports System.Threading.Thread Imports System Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Me.demoThread = New Thread(New ThreadStart(AddressOf Me.ThreadProcSafe))
[code]....
I've been trying to use Microsofts example on their MSDN but I'm getting this error. :
Error1'demoThread' is not a member of 'WindowsApplication1.Form1'.C:UsersAydinAppDataLocalTemporary ProjectsWindowsApplication1Form1.vb89WindowsApplication1
I'm adding multi-threading facilities for the first time. I have a function that is wrapped to be run in a separated thread. This function retrieves data (text) from a combobox and it works for sure without multi-threading.
When I call it as multi-threaded, I get the following error when I try to retrieve the data from the cmobobox: Cross-thread operation not valid: Control 'cmb1stBL' accessed from a thread other than the thread it was created on.
It looks like a restriction of thread-safety... I assume that the child thread cannot read from his parent, to make sure that he doesn't change his parent data. So how can I read the data from the combobox? Should I read the comoboxbox data before calling the child thread?
just wondering if it is possible to have a form and then load up a control on that form but so it runs in a different thread to its parent... i tried:
[Code]...
But it still seemed to be running on the form's thread And just so you know ctlMTTest is just a control that has a button on it, that, when you click the button, a loop runs.
What I am trying to achieve is if there is an error in cell 1 of the current row it returns to that cell. The code below tries to achieve that, but I get an error message thus:Operation is not valid because it results in a reentrant call to the SetCurrentCellAddressCore function.
Private Sub RoomPricingDGV_CellEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles RoomPricingDGV.CellEnter If e.ColumnIndex = 2 And cellerror = True Then
I am running a query in a thread but I can't figure out how to get the result back to the calling function. I am doing something like this:
Threading.ThreadPool.QueueUserWorkItem(AddressOf RunThread, "some query string") Private Function RunThread(ByVal stateInfo As Object) As String Dim myQuery As String = stateInfo.ToString
