VS 2008 - Background Worker Code - Does Not Shows The Result
Jul 30, 2009
I am using a background worker, it runs fine but it does not shows the result. i am using jmcilhinney source to work it out.. have a look.
VB Imports System.ComponentModelImports System.Text.RegularExpressionsImports System.NetImports System.IO Public Class WorkDialogue Private _result As Long = 0L Public ReadOnly Property Result() As Long Get Return Me._result End Get End Property Private Sub
[CODE]...
And the button codding in other form:
VB Using dialogue As New WorkDialogue dialogue.ShowDialog()TextBox2.Text = dialogue.Result.ToString() End Using
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May 7, 2010
I'm new for VB.Net 2008. I am facing some problem about how to make the multiple groups activities running (it might concurrent) based on their own activity's time set? For example: If there is 80 groups and 100++ activities in each group, can i use background worker (create 80 background worker?) to handle this (each background worker handle their group activities.) if in this case (But it will running lag or hang)
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Mar 11, 2009
I have the following code that adds a background worker into a VB.net WPF project:
Imports System
Imports System.ComponentModel
Imports System.ComponentModel.BackgroundWorker
[Code].....
And I get the following error for the DoWork worker event:
Handles clause requires a WithEvents variable defined in the containing type or one of its base types.
It seems like it's missing something in the Event declaration, but can't find it.
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Apr 14, 2011
I have created a background worker using a tutorial. I understand some basic stuff like how to update a label or a progress bar from inside of it. The purpose of this background worker is setup a bunch of variables that are going to be used by several other background workers later. The variables i am setting up are 6 different lists and a multi-dimensional array. The code looks like this for the background worker at the moment.
Private Sub My_BgWorker_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles My_BgWorker.DoWork
For i As Integer = 0 To m_CountTo
[code]....
I would normally use the persons.add to add something to the list, but I'm having a really hard time wrapping my brain around an easy way inside of the backgroundworker to add new values to several different lists(which are going to vary in amount of data values). Is there an easy way to do this? I'm used to just having invokes at the top of a sub to do this but those don't seem to work inside of a dowork sub.
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Nov 11, 2011
I have written a code in background worker which calls a function written in a module. In that function I create an object of an existing form. But on doing so I get error "Current thread must be set to single thread apartment (STA) mode before OLE calls can be made. Ensure that your Main function has STAThreadAttribute marked on it."[code]
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Nov 16, 2010
I want my progress bar to go down as time gets closer to it's next "event", so i guess i need a background worker for that so it uses another thread.How can I get that to loop on a timer so something so i knows where it's zero value will be and where it's current vlaue should be.
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Nov 5, 2010
Can i slow a task in the Background Worker down?
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May 5, 2009
I am using the code below to login to a softphone. However, the login progess is a long process as there are many things that have to be initialized and checks to be made, I have only put a few on here, as it would make the code to long to post.In the code below I am checking if the CancellationPending if the CancelAsync has been called in my cancel button click event, before doing each check. Is this correct? Also if the check fails I also call the CancelAsync and set the e.Cancel to true.
Private Sub bgwProcessLogin_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)
'
' * Perform at test to see if the background worker has been
[code].....
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Oct 18, 2009
I have a background worker which runs, at the start it stops a timer which has it's interval set to 500ms, at the end of the bgworker sub it starts it again. I've debugged and found out that the line that starts the timer up again (tTimer.Enabled=True) runs. However the timer does not resume. I'm don't know, but I'm thinking perhaps because I'm stopping and starting it on another thread it's not resuming properly or the sub it was attached to (via AddHandler) has been reset or something so it's running but not running the code in the sub it was attached to. If I never stop the timer in the code, it continues to run just fine, but I need it to stop at the start.
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Aug 6, 2010
I'm working on a web application that uses the web browser control to get and set info from my website. The content on the site is pulled from different pages and the data the application stores becomes really huge so i used a background worker to do the work and keep the form responsive. On each loop i call to get the webbrowser's inner html so i can sort through it and grab what i need and it works; but only the first time!? After i call it the first time and try to call it again to update the variables the function hangs and then the console shows me a Thread Abort Exception, The try statement i used to contain it doesn't fire off an exception. When i debug the program and i get to that function, it hangs and then just stops working.
The function that loops:
vb.net
Dim ids As String = GrabIDs()
Dim IDCount As Long = ids.Split(CChar(",")).Length - 1
Do Until IDCount = 0
[Code]....
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May 3, 2012
I am using query from a SQLite database as the AutocompleteCustomSource for a ComboBox. Also, I want to load data in separate thread. My LoadData method works fine when called directly, but it fails when it is called from the BackgroundWorker thread. When it is called from the background thread, it throws a Specified cast is not valid exception on the csearch.AutoCompleteCustomSource.Add(hh("Taj")) line. Below is my code:
Sub LoadData()
Dim connetionString As String
Dim cnn As SQLiteConnection
[Code].....
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Jul 15, 2011
I'm writing an application in Visual Basic Express 2008, part of the function being to walk through a folder structure starting from a user specified folder. In my research, I found this thing called a background worker which seemed an appropriate tool to use given the potential size of a target folder structure. I successfully installed the two examples from the library here, and believe I understand the principles involved. Even so, having tried to build this feature into my application, it seems as though it is not working as expected, and, as predicted, debugging a multi-threaded application is a pain in the extremity.
I have this fragment under my "start" button click event -
HomeSource.Enabled = False
HomeCopy.Enabled = False
HomeReport.Enabled = False
[Code].....
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Jul 18, 2010
im thinking just because an app has been sent ton system tray does not mean its a "back ground worker"
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Jun 7, 2012
my backgroundworker as I just cant get it to work. Basically I have a backgroundworker which does a few tasks but I'm trying to implement a progress bar and a label. I'm going to set the maximum value of the progress bar to 10 and then have it updating as I move with each task, also I'm thinking of a label with the progress bar which will display the progress ie
[Code]...
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Oct 7, 2009
I'am trying to make app that will show every file in C:[code]Now how can i add progress bar with the background worker.
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Nov 20, 2008
I have a background worker that used to fire its RunworkerCompleted event when its DoWork routine finished querying a database and writing its output to a file. The bg worker was in a class called Query, which was called from another class called Trigger. A new Trigger Class was created for each monitored event. In this class, there was a structure which stored the config of each Trigger. When this event was triggered (set to TRUE) a new query class is created and it is passed the Trigger class. When the database query, file writing was done, the query class and all its rsources were diposed from the RunWorkerCompleted EventRecently I changed the application so that a new trigger class is not created for each monitored event. There is a single instance of the class but new config structure for each event. When a particular event is trigger, jsut the config structure is passed to a new query class and the sma ething is done in the query class. I just noticed now that the RunWorkerCompleted event is not being fired anymore.
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Apr 15, 2009
I have an issue that I can't seem to find a straight answer for anywhere... I have a For loop that sends a file name to a background worker that contains some long running code and I can't find a way for the parent thread to wait for the background worker to finish... Here is the example code:
For 4
BacgroundWorker1.RunWorkerAsync(fileName(i))
Next
[code].....
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Sep 21, 2009
I have run into this before, When I develop a form to use a background worker to fill tableadapters, the background worker does fine on machines running Vista, but if you run the same thread on an XP machine, the thread gets hung.All the thread is doing is filling a table adapter like this.[code]Why would this run on a Vista machine and not an XP machine?
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Apr 27, 2010
I have created a background worker to go and run a pretty long task that includes creating more threads which will read from a file of urls and crawl each. I tried following it through debugging and found that the background process ends prematurely for no apparent reason.
While Not myreader.EndOfData
Try
currentRow = myreader.ReadFields()
Dim currentField As String
[code]....
This first bit of code is the loop to input from file and this is what the background worker does. The next bit of code is where the background worker creates threads to work all the 'landingPages'. After about 10 threads are created the background worker exits this sub and skips the file input loop and exits the program.
Try
For Each landingPage As String In landingPages
pgbar.Timer1.Stop()
If VisitedPages.Contains(landingPage) Then
[code]....
Also my main thread runs a forms from where this background is called to run but the main thread is supposed to wait for the background process to end unless the user selects another option from the main form.
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Jan 11, 2012
I've been experimenting with background worker to maintain responsiveness and to allow the UI to update while things are being done in the background.I've been having problems getting the background worker to do anything with form controls.For simplicity lets say I have form1 and form2.The background worker is on form1Initially I couldnt get it to edit controls on form1 but by using [code]However the problem came when I tried to get the same background worker to update controls on form2, in this case a text box. With the above code there is no error but it also does not update the text box.Is there an easy way to give a background worker access to multiple forms.
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Mar 10, 2011
i m trying to kill a background worker in the do work event of the worker i was using
backgroundworker.CancleAsync()
but its shows an error saying tat CancellationPending does not allow
how can i kill a background worker after its work gets completed in its do work event
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Dec 30, 2011
currently, i have this code: My_BgWorkerB is the Name of my BackGround Worker
If My_BgWorkerB.IsBusy Then
If My_BgWorkerB.WorkerSupportsCancellation Then
My_BgWorkerB.CancelAsync()
[code].....
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Apr 16, 2009
Is there a way to pause a background worker? What I need to do is pause a background worker when it encounters a file error, wait for a few seconds, and then carry on.
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Jun 7, 2012
I have a backgroundworker which does a few tasks but I'm trying to implement a progress bar and a label. I'm going to set the maximum value of the progress bar to 10 and then have it updating as I move with each task, also I'm thinking of a label with the progress bar which will display the progress ie [code]
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Jun 6, 2010
I have a function it is called ReLoad()
How can i run it as a background worker? so it can run in the background where it does not effect my current running function - basicly so the form will not freeze at all.
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Jun 12, 2011
I am developing a VB application along with MS Access... When I initially load my form I need to put my application to sleep for 3 seconds or else data wont load properly. So for this 3 seconds I would like to show a progress bar displaying a message "Please wait" I tried using background worker but did not find any success... I have gone through many tutorials but for some reason could not accomplish the task.
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Nov 10, 2011
I want to use a background worker control in my application, and have it report progress to a Progress Bar It will download data and stuff, and I want to be able to change the text on a label.
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Jun 10, 2009
I am trying to code a simple background workers class without needing to use the backgroundworker object on a form. This would allow me to use a background worker in any class without writing much additional code. Is it possible to pass in the name of a sub at runtime instead of hard-coding it? To do this I would replace onDoWork and onProgressChanged below and use (Byval onWorkSub as SomeKindOfObject?, Byval onProgressChangedSub as SomeKindOfObject?) instead. [code]
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Oct 6, 2011
I just can't see what I am doing wrong here, since I have implemented a progress bar into my background worker it no longer only runs the once (in some cases I have seen the coding within the foor loop run 6 times)
My coding:-
My progress bar max value is set to 10.
BGWorker Do Work Event
[code]....
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Dec 1, 2011
ive developed my app and am im trying to improve its use ability. Ive created a dvd management app for myself and i have a function that retrieves all the data for all the movies displayed in my listview. It works fine but the interface hangs for the entire time.Ive decided to use a background worker so i can browse other movies with all the data is being fetched.Im having silly problems with getting the index value for my listview when im using the .DoWork()
ive had these errors:
1. Cross-thread operation not valid: Control 'ListView1' accessed from a thread other than the thread it was created on.
2. nvalidArgument=Value of '1' is not valid for 'index'. Parameter name: index
the function works a dream whenvnot being called inside the doWork()
'New Objects
Dim fetch As New Create
Dim download As New Download
Dim parse As New Parse
[code]....
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