I have a search function in my program that uses a background worker in order to get the results. The Progress changed event is used to update the listview with the new item.[code]
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Occurs when ReportProgress is called.
but in my code ProgressChanged event doesn't fire after this line bgwBckp.ReportProgress(1)
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I have a UserControl that has a ProgressBar on it. The purpose of the UserControl is to be able to show the progress % on the ProgressBar as text. To do this it uses the MyBase.Paint event. To make it work the ProgressBar is made invisible and the UserControl is 'painted' with an image of the ProgressBar and then the text is painted on top. The UserControl has a Value property that is passed through to the ProgressBar.Value property.
I use this UserControl in two places, on a Splash form (not a standard Splash Screen) and also on the main form of the application. It works on the Splash form but not on the main form - by work I mean that changes to the ProgressBar.Value property cause the ProgressBar to show its progress. The cause appears to be that in the Splash form case the MyBase.Paint event is called as a consequence of calling Me.Refresh in the Set procedure of the UserControl.Value property, in the main form case it isn't,
i.e. Me.Refresh isn't causing MyBase.Paint to run.
The main form has two BackgroundWorker components. The first gets called (RunWorkerAsync) from Form_Load after the Splash form has been shown. The BackgroundWorker.ProgressChanged event updates the Value property of the UserControl and it works exactly as intended. The second gets called as a result of a user starting an operation and again the BackgroundWorker.ProgressChanged event updates the Value property of the UserControl but MyBase.Paint doesn't run so the ProgressBar remains resolutely static.
Any ideas why it won't respond to Me.Refresh in one case but does in the other? Happy to make any of the code avaialble but didn't want to fllod the first post with reams of it. Here's what I think are the most relevant code sections. First the UserControl
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in my button click event i ececure
If BackgroundWorker4.IsBusy Then
BackgroundWorker1.CancelAsync()
End If[code]....
after proceess completed if press the button again.i got the following error msg
This BackgroundWorker is currently busy and cannot run multiple tasks concurrently.
I understand that this is bad programming practice and redundant coding but I am curios.
I am simply counting a number up to 9999999 in a while loop. The Add() function simply increases that number and prints it out.
Inside the Add() Function I call the Add() function.
My program successfully prints out 12000ish numbers before I get a StackOverflow Exception.
So my question = Is there any way to ignore this error and keep counting?
I have tried On Error Resume, Try/Catch, and throw
My code is as follows.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
While number1 < 9999999
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I am using BackgroundWorker to connect asynchronously to a database. Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
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While my connection is being opened, I have a "Loading" animation show in a lblCalibration. Once it's connected, the animation stops successfully and shows the calibrated record that I am fetching from my db.
However, if there is an error while connecting to my db for any reason, it does not work. My app freezes. The reason is because I am trying to make a cross-thread call while trying to Catch the error in the DoWork event.[URL]..
but still cannot seem to make any progress. Does anyone have any tips or advice on how to properly catch the error and still run BackgroundWorker?
I need to write a long-running process with a While/End While loop.
To avoid freezing the UI, I added a BackgroundWorker object on the form.
Next, I needed to update the UI, but found that the thread cannot do this. Instead, the thread must call ReportProgress() to trigger the ProgressChanged() event.
However, I need to pass the text from the exception (ex.Message) to the event, but didn't find an example on how to do this. I need that text message to update the form's title bar.
Here's the code:
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
While (True)
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I cannot figure this one out.. I have a background worker that will perform a task streaming data from some webpages. this data is then passed back and displayed in a gridview. It has been working fine.
I've recently implemented a listbox, which its values will be passed into the function that the background worker will perform as parameters, originally i had taken a single value from a textbox.
Now, I thought maybe it had something to do with the listbox, so I used a static value, just a simple String, as the parameter, and again, I get the TargetInvocationException was unhandled.. There's no difference in how I perform the task I'm trying to have the backgroundworker complete, the only difference is where it exists in my if condition statement:
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles ScrapeSites.DoWork
Dim results As ArrayList
Dim worker As System.ComponentModel.BackgroundWorker = DirectCast(sender, System.ComponentModel.BackgroundWorker)
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I am trying to get a progress bar to update on my Form while waiting for a process to complete but could not get my progressbar control to update.
First of, I have tried to fix the problem for a day and a half now looking at various codes and examples in the forums but I'm afraid I probably do not have the necessary VB skills yet to troubleshoot my own code. I believe I will be able to eventually fix this after I am done with my VB book
I've attached the relevant part of my code below and the problem is that I can see my DoWork event firing off and changing the time and percentage that I want to pass on to ReportProgress() and the ProgressChanged handler. However, the ProgressChanged handler is not raised until after my Do Loop is done.
Imports System.ComponentModel
.
.
.
Public Class Form1
Private WithEvents TestWorker As System.ComponentModel.BackgroundWorker
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Again, I can see the ProgressChange fire but only after my work (diagnostics) is complete so my progress bar is either 0% or 100%. In Dowork, I can verify that the progtimepercentage variable is indeed changing and ReportProgress is called but ProgressChanged is not being raised until after the job I wanted is done.
I have a project in VSTO/VB using a BackgroundWorker that works fine. It is a form that calls for a web page of information. The web page can take a while, so I have the form calling with the BackgroundWorker.I then have an Excel Addin project that has added the BackgroundWorker project. When I call up the form from the Excel Addin project and use the BackgroundWorker to request the web page, it grabs the web page ok. But the work done upon completion, during the BackgroundWorker1_RunWorkerCompleted method, is resulting in an error message:
View 2 Replies[Code] This is run from inside a backgroundworker. It throws an error, Cross-thread operation not valid: Control 'pbUpload' accessed from a thread other than the thread it was created on. I have read and read and searched and basically come to the conclusion I am going to have to invoke the command but this is new area for me.
View 5 RepliesI am using a background worker's work method to create a new form and show it.
But it throws this error
System.Threading.ThreadStateException was unhandled by user code
Message="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."
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Basically what I'm trying to do is Query AD for AD Computer objects, which are held in a compname variable. Then I go and check to see if I can attach to the WMI (to help filter out AD-joined linux boxes), if I can't, then I mark it as offline and vice versa. I've read and understand that background worker can't update UI stuff, so it needs to be done via the ProgressChanged sub..I want to update a list box on my main form but I can't get the ProgressChanged sub to see my compname variable from the BackgroundWorker_DoWork Function...I'm guessing I need to make the compname a global variable somehow?
View 2 RepliesI have a backgroundworker that is downloading data from different webpages and process them to a datagridview.I get the Cross-thread operation not valid error on the first For loop.
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
dim i as integer
tot = (numPostnrTo.Value - numPostnrFrom.Value) / 10
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I have a program that uses Lucene.net in ASP.NET (VB.NET), when you search a term, results are stored in the Lucene.net data structure "hits".I want to read out the hits into an data structure and work with them, after that I display them in a DataGrid.By searching a term with a lot of results, often (but not always) there is an error by following code :
For i = 0 To results - 1 Step 1
Try
Dim tmpobj As New object_hit(( _
hits.Doc(i).Get("title") + _
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I checked the server; it's a dwh server and has no problems to execute the program.At first I used a ReDim Array, but now I use a List(Of T).
[URL]notice that the tag topic count for C# is in excess of 8900 while the vb.net tag topic count is sitting at 1019. Does this mean that there is a shift towards c# as a .net language of choice. the only reason I decided to build some applications for work using c# was that I like curly braces - after all vb has the same language support as c#, doesn't it so there should be no advantage to choosing one over the other; other than curly braces;)
View 7 Repliesi have identified that the problem here is in the following line:
Tbl_POBindingSource.Filter = Tbl_POBindingSource.Filter & " AND " & Partfilter
Now here is my whole thread:
Do While _filter = 0
Try
Dim POFilters As String = ""
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I have an StackOverflowException in one of my DB functions that I don't know how to deal with. I have a SQLite database with one table "tblEmployees" that holds records for each employees (several thousand posts) and usually this function runs without any problem.
But sometimes after the the function is called a thousand times it breaks with an StackOverflowException at the line "ReturnTable.Load(reader)" with the message: An unhandled exception of type 'System.StackOverflowException' occurred in System.Data.SQLite.dll
If I restart the application it has no problem to continue with the exact same post it last crashed on. I can also make the exactly same DB-call from SQLite Admin at the crash time without no problems.
Here is the code:
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When crashes, the reader has "Property evaluation failed." in all values.I assume there is some problem with allocated memory that isn't released correctly, but can't figure out what object it's all about. The DB-connection opens when the DB-class object is created and closes on main form Dispose.
Should I maybe dispose the mycommand object every time in a finally block? But wouldn't that result in a closed DB-connection?
I need some advice to make a small application running, i need to calculate a integer prime and i use a recursive function inside a while true loop, first i get a random number with random class and then i call the recursive function that checks if it's prime, if it's prime it exits the while. Sometimes it works others throws the stack overflow exception, what i must do to get rid off this exception?
View 4 RepliesI have a directory of images that reside outside the context of my web application that I need to serve to the user. Currently I'm using an IHttpHandler to serve the images and using some javascript to navigate through a set of images (the navigation is primitive for now). I followed examples for using IHttpHandler to serve images closely but when I view the images in firefox the browser hangs and when I view in IE I get a "Stack overflow at line: 0".
Code for the IHttpHandler
Public Class ShowImage : Implements IHttpHandler
Public Sub ProcessRequest(ByVal context As HttpContext) _
Implements IHttpHandler.ProcessRequest
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I have made a login system using OpenID using the following code:
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It takes the user to Google for authentication. I only want to store the user information like email, full name and sex in my DB. I have written the following code to retrive email from Google but nothing is returned:
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I feel like an idiot for asking this question again, as I know it's been asked several times. I cannot for the life of me get this code working even with the answers that have already been provided, so I'm hoping that by offering my current code, someone can help me determine where I'm going wrong:
Dim RSSReader As New Xml.XmlTextReader("http://stackoverflow.com/feeds")
Dim RSSDoc As New Xml.XmlDocument()
Dim NSMgr As New Xml.XmlNamespaceManager(RSSDoc.NameTable)
NSMgr.AddNamespace("atom", "http://www.w3.org/2005/Atom")
RSSDoc.Load(RSSReader.GetRemainder())
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Let's say a custom exception is thrown in the DoWork event for a backgroundworker. How do I pass the custom exception to the backgroundworker so that it ends up being the e.Error in the RunWorkedCompletedEventArgs?
View 1 RepliesI have 2 classess. Role and User like this
Role
Public Class Role
Public Property RoleID As Integer
Public Property CreatedBy As User
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The situation is like when we create roles, we will save who created this role. So i have a CreatedBy Property of type User. Similarly when we create a User, we will mention what role the new user belongs to .So i have a property called "Role" of type "Role". This circular reference giving me StackOverflow exception as its recursive when i create an object of User class.How do i handle this ? should i restucture my entties ? how ?
I have done some reading and it seems that this error comes from recursive calls but I have not done anything in my form_closing handler except for call me.close, that's it.
So I don't understand how this exception has entered my project. All of my data and functionality is still working as I expect. It just seems to throw this exception when I try and exit my project.
what I could check to prevent something like this from happening?
Starting from my understanding about Background worker control, I understands that the background worker runs the code in its "DoWork" method in a seperate thread, while ProgressChanged and RunWorkerCompleted events are executed on the main thread.In my senerio, I report the progress and under an specail condition my application displays a message box to the user in "ProgressChanged" method using MessageBox.Show(). and in "Run Worker Completed" event the application finalize some work. There the sequence is important, suppose that the message is of Yes or No type and finalization depends on it. Now when i run my application, the background worker triggers "ProgressChanged", but as soon as backgroundWorker's cancelAsync() is called the program leaves the current "ProgressChanged" method and executes "RunWorkerCompleted" code first.How can i make sure that the "Run Worker Completed" code executes only after the completion of ProgressChanged method.
View 9 Repliesi'm in the need to start a backgroundworker inside another one.Now...The first one BGW starts a for cycle, and inside this one there is the second BGW that has to upload an image to a server.The trouble is that, the progress event and the complete event of the internal BGW are never called.
View 11 Repliesgood example on backgroundworker control in vb.net for doing some process in background for ex a reading a doc file in textbox by using backgroundworker in vb.net?
View 2 RepliesIs it possible to set a backgroundworker as STA
View 1 Replieswhat is this BackgroundWorker and how to use it? Can it be used as a replacement to System.Threading.Thread??
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