i want to use thread in vb.net 2010 and have problem :( after run the project showed this message for meError > " Controls created on one thread cannot be parented to a control on a different thread."
Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
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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()
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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".
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.
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()
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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.)
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
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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).
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.
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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
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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:
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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
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
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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].....
I've got a form that acts as a progress report for a long running operation, it has a listview on it (which I might be replacing with a DGV soon) that gets updated with progress updates from a background thread that is doing all the work. The method running on the background thread raises events that the form then handles and adds the string passed in to this event to the listview. The method running on the background thread raises progress update events several times a second and for each of these updates the event handler on the form must invoke a method on the UI thread to actually add the item to the listview.
This works fine on my test PC (which has a quad core CPU and 8 GB of RAM) but others have reported that after a while the form goes to the Not Responding state so I'm assuming all of these updates on the UI thread are being requested too often for it to be able to process them all as well as user input.So I'm looking for a better solution and have come up with the following:When the background thread raises these progress updated events, instead of them being added to the listview instantly I add them to a Queue(Of String). Then every second the form would check this queue and remove any items currently in it and add them to the listview - using a Queue(Of T) instead of a List(Of T) should guarantee they come out in the correct order. Both of these operations (adding to the queue and reading/removing from it) would be done under a SyncLock block that would lock on the same object to avoid both threads trying to work with the queue at the same time, so there would still be some contention but I'm hoping it would mean the UI thread only gets busy once a second instead of potentially roughly 30 times a second as it is doing now.Does that sound like a good plan? Can anyone think of a better way of handling this?
I'm calling a c++ dll I made myself - and it appears to be very VERY not thread safe!
I'm referencing it like this
<System.Runtime.InteropServices.DllImport("D:ACS DesktopdcxdcxDebugStringLibrary.dll", EntryPoint:="firstIndexOfKeyword", CallingConvention:=Runtime.InteropServices.CallingConvention.Cdecl)> _
Public Shared Function firstIndexOfKeyword(ByVal s As String, ByVal substr As String(), ByVal substrLength As Integer, ByVal markers As Integer()) As Integer End Function
Is there a way to make this IMPORT create something more threadsafe?
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How do i go about multi-threading that, it's just an example project, so i can try and learn from it. As i'm having a hard time understanding JMC's tutorial as it doesn't directly relate to what i'm trying to do [code]When you hit 'Start', the start button is disabled and the Label1 then changes to "Downloading".The data is then downloaded and put into the Textbox1.Label then reads "Complete" Start button is enabled.
View 5 RepliesIs there anyway to create an OS or Managed thread, so that it can never be interrupted. Thread/Process priorities are not enough.
View 2 RepliesUsually I use the synchronizationcontext to run methods on my GUI thread from a background thread. But now I need to do it the other way around and the synchronizationcontext class doesn't work on threads that don't have a GUI. What I basically need to do is, if there is anything going on on the thread I want to run my method on, I want to pause or interrupt it and run my method and then let it continue.
View 4 RepliesI'm dropping into this function - from several threads - to add an OBJECT to a dictionary collection
Private Delegate Function ReaderRegisterDelegate(ByRef rrFSOb As FSObject) As FSObject
Private Function ReaderRegister(ByRef rrFSOb As FSObject) As FSObject
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It's getting Object reference not set to an instance of an object.The FILEID key being added is F1. F2, F3 and F4 are in the dictionary. Seems like F1 arrived and the object wasn't properly setup. Or thread-slice caused me to see a partially messed with dictionary list?How can I make that a thread safe operation? I thought dropping out to the UI thread was a safe place to mess with code like this? Oddly enough I can go to the immediate window and do this
m_FSObCollection.Add("F" + rrFSOb.FileId.ToString, rrFSOb)
?m_FSObCollection.Count 4
ex.data is a dictionary list that looks like this
directcast(ex.Data , System.Collections.IDictionary).Count 0
So i made this thread using the following
Public DoCopy_thread As New Threading.Thread(AddressOf docopy)
public Sub docopy(ByVal state As Object)
If ListBox2.Items(ListBox1.SelectedIndex) <> "" Then
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[code] For some reason, and I don't know why. The same CustomSplashScreen that had a handle for UpdateText shows to not have a handle when I call .Close().So basically it would show the splashscreen and update the text, but the form would be left opened and not closed like it is supposed to be.
View 2 RepliesBasically, I am just trying to close the thread/process after it's done.
Private psi As ProcessStartInfo
Private cmd As Process
Public Delegate Sub InvokeWithString(ByVal text As String)
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim psi As New ProcessStartInfo("m7.bat")
[Code] .....
I am trying to close the thread so once it's done, it closed for good and my form is closed as well. I tried Me.Close() which results in: "Cross-thread operation not valid: Control 'Form1' accessed from a thread other than the thread it was created on." Error.
Me.Invoke(New InvokeWithString(AddressOf CloseME), e) - Results in parameter mismatch error.
However, things like Msgbox("Done") works perfectly.
I have created a class with a public sub which has a variable with it using byval:
Public Class clsMessenger
Public Sub Messenger(ByVal Port As Integer)
End Sub
End Class
I now need to start that sub in a new thread and pass a varible to it but I am not entirly sure how to go about that. At the moment I have:
Dim ClientConnection As New clsMessenger
Dim ClientThread As New Threading.Thread(AddressOf ClientConnection.Messenger)
ClientThread.Start()
I can't use a global variable because there is going to be multiple instances of this routine running on different threads and each time the variable to be passed will be different.
I cannot access datagridview from another thread...it says that cross thread operation is Invalid... if I use: Form1.Label1.Text = "From another thread" No errors but no update on Label1.Text as well....
View 2 RepliesBasically I want to Create a new thread which create a new timer.I can create a new timer in different button but when one of the timer has an idle time or sleeps the other timers also sleep. I do think because they are running in the same thread.
View 7 Repliesam trying to call a Sub from another thread but it always throwing me an error: Cross Thread is not valid.here is the Sub I am calling from other thread.
View 3 RepliesI have a sub which is run in the threadpool with this command:
ThreadPool.QueueUserWorkItem(AddressOf UpdateStatus)And here's the sub:
Public Sub UpdateStatus(ByVal state As Object)
Dim ini As New INIAccess
If ini.INIRead(GetX_Games, "-1", "Patched", "0") = "1" Then
StatusLabel.Location = New System.Drawing.Point(120, 145)
StatusLabel.ForeColor = Color.Green
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I'm running a bunch of automated tasks in a thread I'm creating via the Thread class. So I'm not using a BackgroundWorker.
During parts of the automation, the thread may exit. This is normal. But when the thread completes, I need to finish up some additional tasks. I can anticipate all of the conditions in which the thread closes, but I'd rather not to do the final tasks at each point, as this will create a lot of redundant code.
So instead, I wanted to write an event that is triggered when the thread exits. I looked through the Thread class, but all I could find was the ThreadState property, which has a Stopped property. But, when I try to add a handler to that property, it doesn't allow me.
I want to know how can I restart a terminated thread?I have a 3 buttons (Button1: Start/Resume, Button2: Pause, Button3: Cancel) code like this;
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If (CrawlerThread.ThreadState And ThreadState.Unstarted) <> 0 Then
CrawlerThread.Start()
CrawlerThread.IsBackground = True
Else
CrawlerThread.Resume()
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When I click to Button1 it starts to thread, then If I click to Button2 it stops as well then I click to Button1 again to resume it. All these processes works fine. But when I click to Button3 for terminating to thread, yeah It works, after that If I click to Button1 to start it again It gets a error: "Thread is not running; it cannot be resumed."
So one of my programs logged an error the other day that I am trying to fix. The error was Collection was modified; enumeration operation may not execute.To overly simplify my code, users can add or delete objects from the collection at runtime. In the background, on a separate thread, a process runs every so many seconds that syncs the data in the collection with the data in a flat file.
To avoid my problem, it seems the most logical to create a COPY of the collection at the start of my second thread's procedure, and run off of that.How do I do that?If I try to say something like.
[Code]...