Code to launch a wmi query on remote computers. This code runs in several threads at the same time.
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For Each objMgmt In oquery.Get 'on some pesky windows XP machines this line hangs forever regardless of the timeout and the thread can never be used to get info from another computer. the only way to "release" this is to reboot the target computer.
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I am using vb.net 2005In my form load procedure I am starting a background thread.The thread is declared as public.
Public
threadMonitorWMI As System.Threading.Thread
And started in form_load
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im trying to terminate a threading.thread using thread.abort the thread runs a download connection so is usually in the middle of socket.recieve or socket.send or socket.connect when aborting i just want to terminate the thread no matter what thread.abort raises an MDA excpetion. so i ticked it off in the debug exceptions menu. now it doesnt raise an exception, but the thread simply wont terminate. my program wont close unless i press top in the debugger.i cant pause downloads because i cant terminate the thread this code wasn't working?
Dim vT As Threading.Thread
For Each vT In clsDownloader.DownloadThreads
If Not vT Is Nothing Then
vT.Abort()
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as for the exception concerning threads being aborted from other threads being dangerous, how is it possible to send a message from a main thread to another thread to abort itself? as far as i know the only way to a abort one thread from another is to just kill it (because i dont know of ways for a thread to communicate with another).
I'm trying to safely kill a thread. In my button click I have:
try
dim bar as new foo()
dim mythread as New System.Threading.Thread(AddressOf bar.Start)
mythread.Start()
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When it goes to abort the thread I still get a thread abort error.
Disclaimer: I know that Thread.Abort is evil. I'm using it as a last resort since some I/O functions (e.g., File.Exists when used on a non-existing network share) block for a large amout of time and do not allow you to specify a timeout.
Question: Is it possible to Abort (as in Thread.Abort) a worker thread started using Delegate.BeginInvoke or do I have to do the Thread handling myself?
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
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I've got some server apps that I've been trying to get some metrics from so I can debug them. I found that when scrolling back up the window I'd suddenly get timeouts from the clients. Sure enough, moving the scrollbar stopped the application.
I'm probably missing something fundemental here, but I can't work out why moving the scrollbar on a Console window would block the thread. It's very simple to reproduce:
Sub Main()
Do
Console.WriteLine(Now.ToString("O"))
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Run that up, and any interaction with the window blocks the thread. In the example below, I just moved the scrollbar a bit and held it in position for a few seconds before releasing [URL]I've tried it with a Timer type loop rather than a Thread.Sleep but the same issue appears. What am I doing wrong (other than not using a service instead!)?
I am developing windows based video application, in my application I have to make multiple video files with different duration from a single video file. To achieve this I am using thread.join method(), when I run my application it works fine but sometimes it hangs and I have got to close my application using Task manager, I can't understand why my application behave like this?.
This generally happens when number of output files are more than 40. Is there any problem with thread.join() function, when number of threads are increased. I am generating a new thread for each output file because this is the limitation of the third party dll which I am using.
I have an application that interacts with third party COM objects. A method of the COM object that I call will sometimes stop responding. I created a Backgroundworker thread to call the function and I am trying to monitor it from my main thread to kill it if it hangs. I have additional code (not supplied) that tracks the processing time using system.timer from the main thread and I raise an event if it exceeds my threshold (this part is fine). This is when I want to kill the thread and stop code execution. The problem is.. if I use the cancelasync method it will just pend since the code execution is stuck on the function call.
The particular function call in the code snippet that hangs is "objCOM.SendDataToServer()". It typically takes 1-3 seconds to return, but if it gets no response it will just hang indefinitely and won't return at all (no errors just hangs).. there is no timeout... and since I don't have access to the source function I cannot supply one. I tried the .dispose() method of the thread, but apparently that doesn't kill it and neither does cancelasync. I just need help figuring out how to KILL this thread so I can reset the server connection and call the function again.
Public Class COMobject
Private objCOM as new acs.manager
Public Sub CallComFunction()
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I am looking to release an ad-supported free app (i want to make it free, but need to cover some costs) in which the ads are basically unobtrusive panels in the corner of the screen. They are webbrowsers which show an image.[code]...
View 6 RepliesOk, this might be something stupid that im not doing right, but here is my problem. Im moving from my 1st form, a small window, into my second form, that is full screen, but it takes like 4-5 seconds to load the full form. It sucks because during this 4-5 second load time, parts of the form at transparent and it just look bad. I think it might be because i have around 35 labels and a few other objects on the form. Does anyone know a way to make this not happen? Im in VB08.
View 14 RepliesThis loop takes forever to run as the amount of items in the loop approach anything close to and over 1,000, close to like 10 minutes. This needs to run fast for amounts all the way up to like 30-40 thousand.
'Add all Loan Record Lines
Dim loans As List(Of String) = lar.CreateLoanLines()
Dim last As Integer = loans.Count - 1
For i = 0 To last
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I am working with the my.application partial class and I was trying to launch some events off of the networkavailabilitychanged event and what I have noticed is that it takes 9-10 seconds to fire that event if I disable wi-fi and pull the LAN cable on my development machine. What I would like to do is significantly shorten this duration. Something like 100ms would be great. If no, what else can I poke for a network status that will handle this response time?
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I wrote a simple auto login script to update my IP address on a certain website. Something really strange is happening now though. The first time I run the program, nothing happens. However, the second time I run the program, that instance will work fine. Then I look in task manager, and the first program is still running, using a whopping 50% of my CPU. I believe VB may be blocking off memory or something, as when two instances are running each is using around 25% of CPU. Then after the second one successfully completes, the first starts to use 50% again.
Here's my code below:
Option Strict Off
Public Class frmTest
Private Sub frmTest_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
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when iam signing up in site then i have this security alert below image how to disable that security alert forever from internet explorer or in webbrowser
View 7 RepliesIm trying to tackel a forever complicated process of comparing listviews
Imagine two listviews (listview1 & listview2) both have 4 colums.
On clicking a command button i want it to go through colum 3 of each row on both listviews ( one and two ) and see if they match, if they dont, do a msgbox of the text of colum 3 of that rows text in listview2.
In one application, I need use 4 simultaneous threads.When the threads finished, I need to update the text of a TextBox.So, I create 4 Textbox, and I wanna the threads change the text to FINISHED.Each thread change one distinct TB.I use this "example"
Dim Terminados As Integer = 0
Private Sub frmEnviarMensagem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Enabled = True
Timer1.Start()
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The problem is, I have an error in the red lines.The error is: INVALIDOPERATIONEXCEPTION "Cross-Thread operation not valid: Control tbPlaca1 Accessed from a thread other than the thread it was created on."I don't use cross threading. Each TB only was accessed for the correspondent thread, and for the "main program".
This is the error message I am getting:
"Cross-thread operation not valid: Control 'Panel1' accessed from a thread other than the thread it was created on." The reason I am getting this error is because I am opening up a new form and then calling these three things:
Panel1.Show()
Label1.Show()
Label2.Show()
why I get this error message because it doesn't occur normally if I open Form2 after closing Form1, it only occurs when I open Form2 after closing Form4.
I have done a program using vb2005 to display reading from my microcontroller bs2 board but have encountered some problems. My code are as follows.
Dim Stop_Rx As Boolean
Private Sub btnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRead.Click
SerialPort1.Open()
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I've encounter an error which is, (Cross-thread operation not valid: Control 'txt1' accessed from a thread other than the thread it was created on.)
When my client try to connect to server I'm getting this error : Cross-thread operation not valid: Control 'l_users' accessed from a thread other than the thread it was created on.
Private Sub _socketManager_onConnectionAccept(ByVal SocketID As String) Handles _socketManager.onConnectionAccept
l_Users.Items.Add(SocketID)
End Sub
Would anyone be able to help me here please. I'm fairly new to VB.net and threading so im just trying to figure out what is happening.When I debug this I am getting the error thread operation not valid: Control 'ProgressBar1' accessed from a thread other than the thread it was created on.
I'm a little lost as to why the error is occuring or how to fix it. I've had to put the progress bar in a separate thread otherwise the GUI crashes
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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)
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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).
I have written an application that loads a form - frmCad as well as AutoCad. It does this via a class which detects when AutoCad quits.
Friend Class CadApp Private WithEvents AppObject As AcadApplication... Private Sub AppObject_BeginQuit(ByRef Cancel As Boolean) Handles AppObject.BeginQuit RaiseEvent Quit() End SubEnd Class
My main class loads frmCad as well as CadApp.
Public Class Cad Private WithEvents frmCad As CadForm Private WithEvents app As CadApp... Public Sub ShowForm() If frmCad Is Nothing Then frmCad = New CadForm frmCad.Visible = True End Sub... Private Sub app_Quit() Handles app.Quit frmCad.Dispose() frmCad = Nothing .... End Sub
When I debug the program, it stops at frmCad.Dispose()The program continues to execute, but all the code after it fails to work.Looking more carefully I get an error message which contains:-Cross-thread operation not valid: Control 'Autocad' accessed from a thread other than the thread it was created on.
My error:Cross-thread operation not valid: Control 'label2' accessed from a thread other than the thread it was created on. I want to be able to give my Public RunBot() sub access to edit Labels, buttons, etc without an error.
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I'm getting the 'System.InvalidOperationException' error on acccessing a thread from other than where it was created. My code is:
'Required by the Windows Form Designer
Public components As System.ComponentModel.IContainer ' changed from private
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My problem is Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on.
System.InvalidOperationException was unhandled
Message="Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on."
Source="System.Windows.Forms"
StackTrace:
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i used it and it works fine then. but as it is mentioned its not a good practice to use it. So what should i do? is it ok if i use this as i am not able to use correct practice. Mine application is not for enterprise purpose. its just my class project, and it works fine even if i put application working in background. System works ok. I dont know how to correct this error.As i dont have that much knowlege of threads.
So please guide me how to fix this in correct way otherwise i am force to go for bad programming practice
Please refer to Windows Mobile Developer Center > Smart Device Development Forums > Windows Mobile Development > Appendtext not working for all my code details
Cross-thread operation not valid: Control 'lv1' accessed from a thread other than the thread it was created on.
Dim lvi As ListViewItem
For Each lvi In lv1.Items
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I've got a single form application.
In the Sub New() of that form I'm creating two database classes.
In those classes if I get database errors (such as connection issues) I'm messagebox'ing the error message and setting an ERRFLAG property.
Back in the Sub New() I'm checking that ERRFLAG and I thought I could ME.CLOSE() - but that's not working.
What all is best practice for this type of operation?
This is what I had up to now
Sub New()
Me.CMCStarting = True
' This call is required by the Windows Form Designer.
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VB.NET 2010, .NET 4/I have a System.Timers.Timer object that does some work on its elapsed event:
Private Sub MasterTimer_Elapsed(ByVal sender As Object, ByVal e As System.Timers.ElapsedEventArgs) Handles MasterTimer.Elapsed
MasterTimer.Enabled = False
'...work...
MasterTimer.Enabled = True
End Sub
My problem is that the work that it's doing sometimes gets stuck. Part of the work is serial communication so it might be getting stuck waiting for a response from something. I've already modified my serial communication code a bit to hopefully solve the problem. However, this timer is basically the heartbeat of a production control application and it is very bad if it were to stop for any reason. I was thinking that it might be nice to put in a fail-safe timeout so that, if the "work" is taking too long, the timer could re-enable itself and try again. I was thinking of something like this:Move the work into a subroutine and create a delegate:
Private Delegate Sub WorkDelegate()
Private Sub Work()
'...work...
End Sub
Call the work by invoking the delegate and then use WaitOne(timeout) on the IAsyncResult to specify a timeout:
Private Sub MasterTimer_Elapsed(ByVal sender As Object, ByVal e As System.Timers.ElapsedEventArgs) Handles MasterTimer.Elapsed
MasterTimer.Enabled = False
Dim workDel as New WorkDelegate(AddressOf Work)
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In that it would re-enter a subroutine that is already running? Is there a way to abort Work() if it hasn't finished after the timeout? In other words, just cease execution of Work() if result.IsCompleted Is False after WaitOne?
In one of my multi threading programs I cannot get my threads to abort. I have about 5 threads and the threads starts one at a time. By the time the fifth thread is started the program gets really slow. The program will not execute pass LoadWheelStn1.
Code:
Private Sub LoadWheelStn1()
If sPortOpenFlag = "T" Then
Dim MyThread1 As New Thread(AddressOf ThreadStn1)
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I am using vb 2005