Background Thread Suspend/resume?
Jun 22, 2010
I have a a main thread and another background thread that does some work (see below).I want to do something within my worker thread and then wait until some other event happens in the main thread before continuing. How do I do this? I thought I could use ManualResetEvent but I can't get it to work properly. I'm a bit confused about the Set, Reset, WaitOne methods and where exactly I should call them from.When the worker thread is suspended it shouldn't affect the main thread.
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System. EventArgs) Handles MyBase.Load
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[code]....
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Jun 3, 2012
Looking for a solution to pause and resume a thread. When I use suspend and resume it says its no longer supported. Here is the code. I'm just trying to get it to cycle between two "do until" events.
[Code]...
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Aug 31, 2011
Is it possible in visual basic to suspend and resume processes. As in entirely pause a process (threads)?I mean an external thread. I'm using Visual Basic 2010 Express btw.
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Jul 16, 2010
Ive got a container with a bunch of child textboxes stacked using dock top. My code updates the textboxes and they vertically expand/contract etc. I'm thinking that my code might run faster if I turn off the layout refreshing until all the updates to the textboxes are done.
I'm getting confused with what I'm reading about suspend/resume layout - do I need to suspend for ALL the child controls, then go through them all at the end and Resume individually?
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Jun 16, 2010
I am looking to introduce a suspend and a resume feature into my program however [code] is there any way to introduce this feature..
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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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Jul 1, 2011
I am trying to use a separate thread to handle specific events in VB.Net. The idea being that I do not want the main application to be held up if a particular event handler takes awhile to finish. How do I get my main thread loop to suspend the thread while allowing it to handle events when they occur?When I create a Windows Forms application, there is a UI thread that handles the UI events. I do not imagine that this thread is continuously polling some variable to see if someone has pressed a button. I imagine the thread is suspended until the OS tells it there is something to do. I was trying to figure out how to ensure that my event handlers were not being executed by the UI thread. From what I have read, I can do this by raising the events from a different thread. But what does that thread do while it is waiting for other events, just exit?
I wanted to know how to create a thread that works like the UI thread, only it processes the events I want it to process. I am not sure how events work in .Net. I understand that event handlers are run on the thread that raises the event. I believe that .Net allocates threads from some thread pool to process events such as timer events. I am not clear on how it works, though, and what those threads are doing when they are not handling events.
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Dec 31, 2010
Is it possible to wait/suspend execution for a certain amout of time without hanging the main UI thread?
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Jun 2, 2010
It seems that there is a glitch in Vb, While having some tasks ( Thread ) queued using Tasks if you try to use Invoke, the thread do not resume when the delegate returns.If BeginInvoke is used, it works but the problem is that it become impossible to execute a delegate synchronously.This does force the use of the AutoResetEvent to control the thread.The problem comes when the thread execute some code in a other classes, using a single AutoResetEvent within many classes just give a very dirty code.
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Oct 6, 2011
I have a thread running on my application that checks a database every so often to decide whether or not to update nodes in a treeview.
Each treeview node represents a document and I have an open button that opens the document for the user.
When the document is opened, I wanted to suspend the thread that refreshes the node list until the document is closed.
I have MyThread.Suspend and MyThread.Resume. But the document viewer is on another thread.
I created functions for suspending/resuming the thread in the application. I have delegates in the viewer to call those functions from another thread. But I'm still getting an Error. "Thread is not user-suspended. Cannot be resumed" or something of the like.
But I realize that Suspend and resume are obsolete functions, so what class or objects should I be looking into and if it didn't take up too much of your time, a small example as well?
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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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Dec 4, 2008
A non-UI thread in my prog needs to obtain data from a UI listview control. To prevent cross-thread errors I use the following, but it freezes the prog (probably because the "Else" part is never called).What am I doing wrong?
[Code]...
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Jan 26, 2010
I have a program that if user presses a key(while the program isn't focused),it presses some keys(some kind of macro to aid gamers).The program works,but I cannot stop the background thread.I use "t.abort()" (t is the name of background thread) but it keeps working(even when I close all forms) and at TaskManager "keypresser.exe" is still there.[code]
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Oct 4, 2010
I have an application that I need to load data in a background thread and make available to a combobox or list box on my main form or UI Thread. I am really new to threading in VB and how to best accomplish this. Here is some code from a test project:
[Code]...
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Jun 29, 2011
I am a novice in Threads, but I want to know how to order thread execution in my scenario, and is the following :
UI Thread : Windows Form Background
Thread : Kind of print daemon
implemented with recursive methods
IO Operation : a StreamWriter that do
the job of File.AppendText()
When I execute my main app.exe, sometimes it launches the Windows Forms and the execution process in the task manager (app.exe), in some opportunities its just launches the execution process in background. How can I determine the behavior of launching UI, I have to establish a priority or somewhat else? Code: I'm using framework 2.0 and any answers could be writted in C# or Vb.Net.
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Apr 7, 2011
I am in the planning stages for developing a VB.Net class (let's call it OpDAq) that is to obtain data via an API provided by a COM object (AxInterop.TWSLib) that makes requests to an Internet server. The API provides data via events. Class OpDAq should do its work on a separate thread; it takes several seconds (sometimes up to ~10) to collect the desired data. One should be able to create several instances of OpDAq in order to collect data in parallel. The class would be given a reference to the TWSLib object when its constructor is called, as well as several parameters. There needs to be a way for the class to provide results, preferably in the form of a generic list.
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Aug 28, 2011
I'm looking for a configurable way to run some code on a background thread and I'm not too sure what the "best practice" would be. Currently I have something along the lines of:
Dim sendEmails = Sub()
Dim emailToSend As New SendEmailRequest()
TransferCommonValuesTo(emailToSend, request, sendingUser)
usersToSendEmailTo.ForEach(Sub(u)
[Code] .....
Is this a good way of implementing my requirement? This will be called from an ASP.NET front-end (although others are possible) and I am using Framework 3.5.
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Aug 16, 2011
I've got an application with a ListView and I want to loop through each item in the ListView. But I want to do this in a separate thread.
This is a very simple version of the code - but its error is the same:
Private Sub StartToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles StartToolStripMenuItem.Click
pingThread = New Thread(AddressOf loopingRoutine)
[Code].....
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Apr 6, 2012
I have a BackgroundWorkerThread which I want to use serially.So some of the code in the UI thread will look like this [code]But of course I can't do the second RunWorkerAsync until the UI thread has seen the RunWorkerCompleted event indicating that the "Sequences" work has been completed (or somehow knows that the "Sequences" work has been completed).So I need some sort of synchronization between the two RunWorkerAsync calls, but whatever I use cannot hang up the UI thread because it has to be able to handle ProgressChanged events.Maybe the RunWorkerCompleted event could make the second call but I really don't like that structure.So how do I delay the second call to RunWorkerAsync (for the "Templates" work) until the background thread has completed the "Sequences" work?
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Mar 2, 2010
I am running sum of my code in a background worker and I need to show sum tooltip text on a label, but nothing shows up.[code]...
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Jun 9, 2009
Im trying to run a thread in the background. The sub would take a string as as input and the text to speech object would read the string.
1st problem is: How do I pass my value strIn to my sub SpeekEventWorker when im calling it like this
[code]...
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Feb 24, 2009
I can't seem to find a good tutorial on how to access uithread components from the background thread.. It seems like there is different means of accomplishing this. I'm not picky about which one I use.
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Apr 6, 2011
I have searched the forum and found several forums related to the backgroundworker thread but have been unsuccessful in finding my answer.My objective is to display an animated gif or progress bar while the program is executing a particular method which can take upwards of several minutes to complete. I cannot get the second thread to run the progress bar while the main progrem is executing the time consuming method. I have created a demo based on another thread and can't seem to get it to create two threads. I was attempting to get the backgroundworker to execute the progress bar while my main code runs on UI thread.
[Code]...
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Jul 8, 2011
I'm using the code below in a separate (background) thread, in order to read parts from a file, so they can be uploaded.
The problem is that when the user stops the upload, the thread is sometimes aborted while it's still reading from the file. This keeps the file locked and when the user starts the upload again, the following message appears.[code]...
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Jul 2, 2011
My application has a total of 1 form. I have several modules, one of which is a module that handles a background worker dynamically. But what I need to be able to do is update a textbox from the background worker thread. Again, this code is contained within a module, not directly on the main form, so I am totally clueless as to how to make a reference to it. It's easy in WinForms, but I can't for the life of me figure out how to do it in WPF...
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Jun 14, 2010
Currently I have a background worker doing a bunch of stuff and if a condition is met, it throws up a MessageBox for the user to pick from an the background thread pauses like I need it to, however most of the time the Messagebox shows up behind the main form (which is on the primary app thread, the UI thread) and I'd like the BW code to pause until it's acknowlegded and I also want the MessageBox to be owned by the main form (so it's always displayed in front and you can't get to the main form until you acknowledge the MessageBox. Later I'll be changing the MessageBox to be a modal form that matches the app's theme (I'll be opening this form using .ShowDialog()) should I go ahead and make that form now?
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Apr 25, 2012
I have a application which processes 1000's datas.. for each processing it needs to update gui and db and many variables in my application. So what i have planned is to use 50~90 background worker with my own algorithm of thread pool, synchronization and thread close.So here is it efficient in terms of memory and performance. just confused what to use.. backgroundworker componenet or standard thread.
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Feb 24, 2009
I'm using the webbrowser control in VB.net. I want to click a button and have the webbrowser go to a certain website (done). Then I want it to wait a period of time and then do something on the page its on. The part I'm having a problem with is the waiting period. In the main form I have no problem manipulating controls or anything like that.
One solution would be to use thread.sleep() but that locks the ui and I don't like that. What I am trying to do is have a backgroundworker do the waiting then perform the necessary actions on the webpage, but the backgroundworker isn't able to access that thread, makes sense. I've explored delegates but that doesn't seem to do what I want as it doesn't allow me to put the background thread to sleep before it does its work.
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May 30, 2011
I am testing a background workder. I am running the following code for the test.
Private Sub bgwTest_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bgwTest.DoWork
Dim a As Integer = 0
Do While a < 10 'Infinite loop
ComboBox1.Items.Add(1)
[Code] .....
But this code generates the following error:
"Cross-thread operation not valid: Control 'ComboBox1' accessed from a thread other than the thread it was created on."
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May 19, 2010
Can someone tell me how to get the selected text in the combo as it encountered cross-thread in the following code:
[Code]...
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