Add Background Workers To Prevent Freezing
Oct 3, 2011
I am a bit of a noobie with vb.net and I made this application that does a lot of http requests and stream reading. But when it does this it always freezes my application.So I did a little research and found that I could use background workers to solve this. But I have no idea where to start. So if you could look at my code and tell me where and how I can add background workers to prevent the freezing that would be awesome.[code]
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Feb 13, 2010
I create two background workers in my program;
' set up the background workers
Dim Bgw1 As New System.ComponentModel.BackgroundWorker
Dim Bgw2 As New System.ComponentModel.BackgroundWorker
Bgw1.WorkerReportsProgress = True
[Code]...
Note, I've tried googleing, I've came across a article sateting that if you have to handle more then one task in the background, you should use System.Threading [URL]../showthread.php?t=101283) But I don't know what team mean with it?, or how you should use System.Threading to back your own 'background worker'.
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Apr 1, 2012
I don't really understand background workers much but would like to be able to use them in my programs, could someone give me an example with some good notes to help me understand how I might use the background worker with around 10 threads just to handle something simple like a math problem.
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Feb 23, 2010
For my project I connect to a large number of variables in multiple Beckhoff PLC's. I connect to the PLC in the Form load event.But the first time connect to all plc's taking too long.The data from the plc's. be sent to my program can not cope with the private sub OnNotification. This is because the program is busy with making connections with various other plc's.If the program is fully launched it works ok, but I also want to start working properly.I solve it just with a timer and a counter. Each program cycle I make a connection, the next cycle the next etc.until all connections are made. This should be better.I would like background workers use to make the connections to the PLC's. bgworkers provide the connection.The main program is not blocked, and the incoming data from the PLC's can be handled properly In the form Load event I start the bgWorkers containing the code for connect and AddHandler. Unfortunately it will not work this way?
Imports TwinCAT.Ads
Imports System.IO
Public Class Form1
Inherits System.Windows.Forms.Form
[code]....
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May 19, 2012
Okay so I've dug around all day and found that using multiple "background workers" would do what I would need for my application.How can I create 4 background workers and then feed the urls to the webrequest from a listbox? [code]
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Oct 30, 2009
How to use the background workers in my case. while my web cam is trying to start i want to show a progress bar.
Private Sub strcam_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles strcam.Click
mycam.startCam(PictureBox1.Handle.ToInt32)
End Sub
I tried many methods to achieve that without any luck. I tried also application.doevents().
I have a gif image that shows a circle go round like the one on vista. However when i use the application.doevents() the circle is shown BUT it start go round only when the web cam starts....I don`t know what to do.....I need somehow to perform two tasks at the same time. Can bagroundworkers used in this case or i need to do something else?
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Jan 26, 2011
I have been pulling my hair out trying to get this to work. If I step through the code in debugger it all works great. My problem is if I just run it, only the last task responds. I'm guessing I am overwriting the background working or something. I am sure I am doing a few things wrong but my code is now messy as I tried many way while searching. I know of the threadpool and .Net 4.0 tasks but having a hard time getting to do what I need.
Basicly I am writing a program (trying more likely) that takes a list of computers and pings then, then checks their uptime and reports back.This works fine in the UI thread (Obviously that locks up my screen). I can have the background worker just do this, but then it does each computer 1 by one, and while the screen is responsive it still takes a long time.
So my answer was to have a for loop for each server launching a new background worker thread. My solution does not work.I have seen other threads that I could do it, but I need to use with events to call code to update to UI when each is done.
What is the most simple way to do this?
Here is my code. Most is just copy paste + modify till I get it working right.
So In the main class I have the testworker.
(I tried using Testworker() but it said I could not do that WithEvents)
When I click the button the list loads.
Private WithEvents TestWorker As System.ComponentModel.BackgroundWorker
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles Button1.Click
[Code]...
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Sep 7, 2010
I am dynamically creating an unlimited number of background workers and would like to handle errors from them.
In a try statement I am using the following:
Catch ex As Exception
'Me.BeginInvoke(New UpdateTextCallback(AddressOf Error_Text), New Object() {Message, Account})
Exit Sub
End Try
I have commented out the BeginInvoke command because I can not get it to work. I get an error the the handle has not been created. This subroutine is in a module and I can not figure out how to get the invoke to work.
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Mar 15, 2010
I need to write a VB.Net 2008 applet to go through all the fixed-drives looking for some files. If I put the code in ButtonClick(), the UI freezes until the code is done:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'TODO Find way to avoid freezing UI while scanning fixed drives
Dim drive As DriveInfo
Dim filelist As Collections.ObjectModel.ReadOnlyCollection(Of String)
Dim filepath As String
For Each drive In DriveInfo.GetDrives()
[Code] .....
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Mar 9, 2011
My program becomes unresponsive when I download Data using WebClient.OpenRead(). What can I do to prevent the program from freezing while downloading the Data?
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Aug 11, 2011
I've been trying to figure out what is going on with this code, but it looks like I need some help. The issues I'm having is when I click a button that executes my background worker, it freezes and the UI comes back once the listview control is populated.My guess is that some part of my code under the backgroundworker_dowork function is trying to update something on the UI thread causing it to freeze. I just can't figure out what is trying to call the UI.
The user is supposed to click a add server button and enter the server name. The server name will be added to the ListView control. When they click refresh, the background worker is executed which attempts to get the DNS name, IP Addresses, and online/offline status.
Obviously, I'd like to run this code without freezing the UI. Does anyone have any idea on why this might be happening? My guess is because the ListViewItems are passed to the background worker and still have a reference to the control running on the UI thread. Am I right with this statement? If so, how do I change my code to get rid of that reference?
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Oct 10, 2008
I seem to be having an issue with my form's background overlapping.I have two forms. One form is called the "mainscreen" and the other form is a small bar at the bottom of the mainscreen form, which shows different labels on a set timer interval.Anyway, the mainscreen will soon have a system in which it also runs different screens on a set interval. However, I seem to be having issues with the mainscreen already. I have set it to load a background image, using this code:
Code:
Me.BackgroundImage = New System.Drawing.Bitmap(My.Resources.image1)
[code]......
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May 31, 2011
I have the following portion of code on a Click Event on my page:
Dim ts As New ThreadStart(AddressOf SendEmails)
Dim t As New Thread(ts)
t.IsBackground = True
[code].....
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Jan 23, 2012
Basically after I queue all works, I want to wait until all I queued has been done. How do I do so?[code]I notice there is no way to know how many threads are still running in the threadpool.
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Feb 25, 2009
I'm trying to use a loading overlay on top of a Windows form that adds a 50% opaque layer on top of a windows form with a loading GIF, while it does what it needs to do in a background thread. The overlay is a windows form that I'm drawing in the onPaint event.
The loading overlay works fine on multiple different form loads, but fails to work properly when summoned to ensure patience during a 30 second upload process (That Prints a Word Document to PDF, then uploads that PDF to a SQL Server). This upload collects some data from the form, puts it into an Object, then operates entirely on a background thread. The loading overlay will appear, show the first frame loading GIF, then just freeze. The onPaint is getting fired and the image frame is being updated, but it isn't visible
Constructor sets the form to be UserPainted:
Sub New()
InitializeComponent()
SetStyle(ControlStyles.UserPaint Or ControlStyles.Opaque, True)
End Sub
[Code].....
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May 25, 2010
I have a FileSystemWatcher monitoring a folder, and when many files are cut and pasted into the folder, the GUI freezes, as the 'Changed' event is fired over and over. Any way to deal with this?
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May 20, 2011
My program keeps freezing. Here is my [code]...
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Jun 10, 2010
The application is freezing on SetWindowsPos,
Sub AOnTop(frmID As Form, OnTop As Long)[code]...
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Oct 8, 2010
how do I delay my program without freezing? I am sure there is another way to do this without timer.PHP uses sleep(). What do VB use?I tried some Delay or Sleep function but don't seem to work..
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Jul 30, 2011
I'm a VB.Net newbie, and would like to write a small app that runs a While loop to check a DNS domain name, and exits once the domain has been registered.
I found code at How to Get Host Name and IP Address in VB.Net - .Net Articles & Samples to resolve the hostname and handle the "No such host is known" error if it still hasn't been registered, but I have a couple of issues:
1. How to make sure the GUI is correctly displayed even though there's an endless While loop? Should I use some kind of asynchronous call so that the window doesn't freeze?
2. I'd like the app to mimize to the icon bar, and have its window title display some status information ("Still waiting/Registered!") so that I can simply move the mouse over it and know whether the domain has finally been registered or not.
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Mar 6, 2012
I have an application that does not load a main form. My start up object is Sub Main. I am not using the application framework. I have several classes that handle different parts of the program.
objAlerts is the main one being used for this issue I am having.
This is how they are referenced in the main program class.
CODE:
This is the unfinished objAlert
CODE:
My issue is that the windows (alert.Show) open in a frozen state where the mouse pointer displays the hoursglass and the window does not respond. The windows show in the list of objects no problem.
Is there a special way that I should be opening these? I can open windows on the main class no problem.
I read that <form>.invoke(alert) might work, but there is no invoke on the main class according to VB.
I am thinking this might be a threading issue, but I don't know how to fix it because this is the first program that I have made using a Sub Main instead of a form.
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Jul 30, 2009
I have MDI parent and child windows that were working fine but now clicking on a dropdown doesn't do anything, also scrollbars cannot be moved. Other controls are still ok, buttons and other links are still working. I should also note that if I change the child to load in a separate window all the controls work again.
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Apr 4, 2009
Lets discuss about those created active x which got created in VB6 and not working in Vista.Here i will let you know my problem,no idea wheather we need to upgrade any runtime file in VB6 or in vista?
I have done an ActiveX to get client MAC address as its major part and runs over IE.it is successfully running in Win2000, Win2003, WinXp and even with IE7 with previously mentioned Window versions.
This ActiveX was developed in VB 6.0.
This ActiveX gets installed atomatically through a cab file, whenever the application was accessed first time.
this cab file work fine in WinXP but when we try to run this cab file in vista IE get hang
Now, we have to support it with IE7 over Vista.
let me know what should I do to make it compatible with IE7 and Vista. I am using Vista Business right now.
When the application was accessed through IE7 for the first time, ActiveX installation dialog appeared. I pressed the Install button but then IE7 threw an error message that "Internet Explorer has stopped working". After that each time, whenever the application was accessed IE7 threw the same error message.
Cab file i made in VB6 using internet and deploy package wizard,along with cab file we will get one HTM file also to get Object id and code base along with version,even if we try to open this HTM file then also IE get hang.
I tested by manually registering the ocx, also turned off the Protected Mode and enabled my ActiveX through Manage Ad-on as well, but to no avail.
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Aug 12, 2009
I made a game in VB .Net that uses tcp and sends messages back and forth.What is happening is, every so often, the message cannot be sent quickly enough, so then the TCPObj.connect() method goes into a loop, until it reaches the timeout and then spits out an error. Most of the time though, it never gets to the error, my application just freezes, and then comes back after TCPObj.connect() succeeds. How can I make the connect() method do application.doevents while it's trying to connect? Basically, I dont want it to freeze up my whole application. Since tcp.connect() is a .NET method, I can't go in and add application.doevents.
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Dec 23, 2011
I have a loop and within that loop I'm running a Dispatcher Timer.[code]Basically what I want is to show each item in the items list pausing after each on for 5 seconds. I want to show elapsed time in a label and after the elapsed time hits 5 seconds show the next item. This is not possible using the Thred.Sleep method, because it just freezes my application for 5 seconds, and shows the next item without ever updating the label with elapsed time.So what to use instead of Thread.Sleep to not freeze the application and update the label with elapsed time?
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Jun 12, 2009
put delay in vb.net without freezing form
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Aug 21, 2010
Is there a way to stop or minimize forms and dialogue boxes from freezing? they seem to take up a lot of memory when loading to the point that they some times look transparent for a few seconds.
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Mar 8, 2012
I was messing around with the listview Control first,, And when i got it working i thought what's this backgroundworker thing,,so i read up on what info MS had on the MSDN page..and slapped it in here..and i thought i had it working ok until i tried to move my project application to the side to reply to a instant message i got..and then i noticed that it froze up .and looked like it was using alot of system resources,But wait let me back up just a bit.originally i was trying it with a fairly small number of items, and then i seen on here where someone had posted a rather large index for testing his app with,,and while trying to load that list that's when the issue was noticed i don't really plan on loading a list as big as that test index was but, I would still like to know why the program did what it did using the code below.I'm not really asking for it to be too altered, i kinda like all the controls i have in it the moment,, and the way it loaded as well.
[code]...
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Dec 10, 2010
I wrote a program that visits each link in a listbox and then parses some data from the HTML. [Code] It works fine for 100 or so items, but when I load a big list (2000 items), the GUI seems to freeze. How should I fix this?
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Apr 9, 2011
this is urgent. i have a form in which i need to give timedelay of 3 seconds before each line executes. But when i try system.threading.thread.sleep its freezing the UI and furthermore all delays are executing as one single delay. that is
[Code]...
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