VS 2010 - Background Worker - Display A Label To Say "Done"
May 16, 2012
I have a an idea of how a background worker works but I was hoping someone could give me some advice. If I run a background worker, and in the Do work if I run some coding which edits a file, and in the RunWorkerCompleted I display a label to say "Done". Will the label only say done once the coding for editing the file has completed OR do i need to put this code inside a process or something similar? and the label will only say done once it says process. close?
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Sep 22, 2009
I ran into the problem of not being able to set a labels text from a background worker thread and came across the way to do it, I modified the sub (which only worked for a specified control) to try and make it work with any control I specify, but I get parameter count missmatch on Me.Invoke(d, New Object() {[text]})
Delegate Sub SetTextCallback(ByVal [text] As String, ByVal lblControl As Label)
Private Sub SetLabelText(ByVal [text] As String, ByVal lblControl As Label)
If lblControl.InvokeRequired Then
[code].....
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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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Aug 17, 2011
i want background worker to use file copy, how?
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Feb 19, 2012
I have some code that gets the documenttext of the current page in the browser, the trouble is that im trying to use it in a backgroundworker so the ui remains responsive. Everything works fine as is If I run from a button click event, but in the background worker I get errors when trying to use the webbrowser.
'if urltocheck is blank use hidden webbrowser to get page text
If urltocheck = vbNullString Then
'make sure browser isnt already loading
[Code]...
Thats the code how do I make these calls the the browser from the backgroundworker? Or how I can I run an enormous for loop from the ui thread, and still keep the ui responsive?
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Jun 19, 2012
It's always been my understanding that ByVal means is that you are passing a copy of a variable to your Subroutine. You can make changes to the copy and the original will not be altered.So if that's true I have two questions- How is my DataGridView updating without me passing the arguments back to it- The backgroundworker works fine as long as I don't reorgnize the columns in the datagrid.
'I pass the rows of my datagridview to the background worker
bgwGetHostStatus.RunWorkerAsync(dgvMonitoredSites.Rows.Cast(Of DataGridViewRow).ToArray)
'It grabs a website name from the IP column and reports if it's down or not in the status column. Now if
[code].....
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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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Aug 25, 2011
I i'm attempting to add child nodes to a treeview inside a background worker's doWork() method.
I'm getting an exception because I'm in a different thread, and need to use the invoke() method.
Can anyone point me in the right direction?
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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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Dec 11, 2011
how to put this on a background worker without getting cross thread errors??? trying to upload a childform object values to an access db.I don't work in IT,Our company's LAN so slow that it takes around 3~5 seconds trying to update/insert values in access using the code below so putting it on a background worker i think makes the app immediately usable once save/upload's called unless otherwise somebody could suggest a faster way to speed things up.[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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Dec 28, 2010
I made a lot of letters, and I set all of thiers background color to Transpert. I STILL don't see any transperancy, because when I put "one letter on the other one", i can see thier background.
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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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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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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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