VS 2010 Thread To Check Main Program Execution
Apr 27, 2011
I feel like the answers I seek are rather obvious so I feel silly for having to ask, but I just can't seem to figure this out (I'm new to threads, and am really only comfortable using them in Java at the moment). I have an Excel Addin application created with VB.NET, and I've noticed that occasionally while it's running some code (it's no one specific block of code) the program execution will just stop. This is especially problematic when I've set ScreenUpdating to False for Excel because the users then have to completely close out of Excel to get ScreenUpdating to true.
[Code]...
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Dec 31, 2010
Is it possible to wait/suspend execution for a certain amout of time without hanging the main UI thread?
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Sep 2, 2010
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)
[CODE]...
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).
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Feb 10, 2012
I have two applications. For performing certain functions, i run a second exe, via a process, and wait till it is complete (exited) to continue with my main application. I run through many repetitive functions on different files.Everything runs fine however, when i am doing a run and it is on the x loop number, the main application seems to halt the secondary process exe. I can only assume this is what is happening as, if i close/stop (not pause) my main application in VB, the second exe continues from where it was halted until it completes.
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Dec 16, 2011
I have an application I've written for some of the people at work and there is one bug that I have no idea how to solve. The application is multithreaded so that the main form can be updated with new information as it comes in. Throughout execution, several other forms come up as well (one at a time).Every so often I get reports that the program freezes. When I check out the program it looks like the main form is not being updated(checkboxes are see through, textboxes are blank) and the main form can't be moved around. This only seems to happen sometimes when the program is left for long periods of time (+30 min) and only on the released .exe and never in the debugger(as of yet). I've tried leaving the program running overnight and it had no problems.
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Mar 4, 2009
I'm creating a Client Server application which involves theServer running some scripts in clients and getting back results in an automated way. In Server, other than Main thread, i have 2 worker threads, a) one monitoring response from clients and b) the other scheduling next available job to respective client which executes that job. The issue here is ,I want these worker threads to write the status of their work in the UI(which comes under Main Thread). Also i need to write things in worker thread in a Data table and Rich Text Box in Main thread. But, I can't do so, since it has been blocked to access one thread's function or property directly from others. Is there any work around to do this?
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Nov 12, 2009
Preface: I know this is an unusual/improper way to do this. I can do this with a "real" ShowDialog(), background worker/thread, and so on. I am trying to do specifically what I describe here, even if it is ugly. If this is impossible for X reason, I have created a fancy progress dialog for some of our long running operations. I need to have this dialog shown on a new thread while having processing continue on the calling (UI in most cases) thread.
[Code]...
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Jul 26, 2010
I have a thread in an application which calls a sub routine Main(). The Main sub routine in turn call several sub routines/functions from with the same module,several different classes in the same application. Also some sub routines/functions call routines from a class library. Now say the routine/function in class library goes into a infinite loop and never returns. I would like my thread in the application to raise a event and display message to the users about the infinite loop. I am giving some sample code for the application.
Imports System.Threading
Module VMain
Public gbSuspend As Boolean
[CODE]...
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Aug 4, 2011
I'm working with BackgroundWorker, I want the BackgroundWorker do the retrieval process of data from database while the user can still do another task on the form. The problem is, after retrieving the data, I can't seem to access the ListView in my Form from the DoWork event of BackgroundWorker, I will populate that ListView using the data I've retrieved.
Consider this example, this is how I'm doing it:
Public Class Test
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[Code].....
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Sep 24, 2009
could someone tell me how to fire an event in main thread from another thread as well as fire and forget without use a new thread?
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Dec 31, 2010
I'm reading data from a serial port, but the DataReceived event of SerialPort is handled on it's own thread. I want to handle this on the main thread, but simply declaring an event and raising it still results in it being processed on the SerialPort thread. I'm assuming I need to declare a delegate I can call, but I don't see how that would work.
For example, I want to call Sub HandleDataReceived() on the main thread from the DataReceived thread, having HandleDataReceived() run on the main thread. How would I do this?
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Feb 15, 2011
My program keeps crashing every time I try to run it on another machine other than my own dev system. It runs just fine on mine but crashes on everybody else's when I install and run it. To make matters worse, it only gives me the generic "[name here] has encountered a problem and needs to close. We are sorry for the inconvenience". So i never can find out why and where it is crashing!!!!
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Jun 23, 2012
According to the answers to another question, the VB user interface cannot be updated if the thread that created it is busy: hence why big computational jobs usually have to go in a background task.Here's what's mystifying then. I have the following code. It's called over in-process COM, like this
client calls showform()
client does loads of work, freezing up its own UI in the process
client finishes work, returns to updating its own UI
At step 2, the VB form is there but frozen - you can't interact with it. At step 3, the VB form becomes usable. But why is this? Surely the thread of execution has returned to the client? If the client is somehow handling events for the form, by what magic did it know what events to handle and where to send them?
[Code]...
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May 12, 2011
Is it possible to use a sub Main() to start you're application rather than a form, if so how? Also how do you implement the cmd commands such as "[application path here]program.exe colourclicker" The above command would start the program but would only show a certain form.
EDIT Is there another way other than unchecking the 'Enable Application Framework' checkbox? (As this disables XP Styles and uses the ugly classic windows styles)
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Nov 18, 2011
I'm in the Progress of changing a big Application from Singlethread logic to Multithread logic. I'm currently move Dataloading Logic into a sperate thread, and work with callbacks after they are finished. I have Synclocks in place in order to ensure threadsafty. But sonetimes the Synclocks wait even if there is no other thread with the same synclock active. Is there any way to find out what witch thread they are waiting for, and why? BTW, I have FW45 installed, may that be the reason, since it'S a inplace upgrade for FW40?
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Aug 19, 2009
I have a vb.net application that uses threads to asynchronously process some tasks in a "Scheduled Task" (console application).We are limiting this app to run 10 threads at once, like so:
(pseudo-code)
- create a generic list of 10 threads
- spawn off the threadproc for each one
- do a thread.join statement for each thread to wait for the longest running one to complete.
What i am finding is that if the code called by the threadproc contains any "Debug.Writeline" or "Trace.Traceinformation" statements, the thread hangs. I can see the thread in the Debug - Windows - Threads window, and switch to it, but it highlights the debug.writeline statement and never gets past it. is there something special about the Debug or Trace statements that make them non-thread-safe? Any idea why this would hang things up? If I leave the debug statement in, the thread never completes. If I take the debug statement out, the thread completes in less than 5 seconds.
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Sep 15, 2010
Me.Focus() doesn't do the trick, my program is hereQuote:
Public Class Form1
Declare Auto Function mouse_event Lib "user32.dll" (ByVal dwflags As Integer, ByVal dx As Integer, ByVal dy As Integer, ByVal dwData As Integer, ByVal dwExtraInfo As Integer) As
[code]......
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Nov 14, 2011
I have a per-call WCF service that serves a number of clients. I'm looking to speed up the services by running some background processes so they don't block or slow down the main function of the services.
One example is that the main function needs to return a set of data, while the background thread needs to record some statistics based on the parameter(s).
Code:
Public Function GetAccountDetails(id As Integer) As AccountDetails
Dim retVal As New AccountDetails
Dim a As New Accounts
[Code]....
If I use this background thread to record the statistic it doesn't block the main thread from returning the data to the client.
It's been working well in test scenarios, but my question is, are there any dangers with leaving this thread to execute without Joining it before returning the data to the client? Could there potentially be any loss of statistic data? Could there be potential memory problems on the server side?
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Aug 13, 2010
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()
[code]....
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".
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Feb 2, 2011
There is a problem with standard System.Timers.Timer behaviour. The timer raise Elapsed event with some interval. But when time of execution inside Elapsed event handler exceed timer interval then thread pool begin queuing event handling. This is a problem in my case. This is because with my Elapsed event handler I fetch some data from database and doing something with it and finally save results back to database. But data handling should be provided only once. So, is there a way to prevent from queuing elapse events for System.Timers.Timer.
As illustration for this issue you can consider next test program:
[code]...
2) Second way is about SynchronizingObject, but it is a valuable only for Windows form application or required additional development of code for implementing object that would be implements ISynchronizeInvoke interface. More about this way you can find here
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May 17, 2010
Trying to get it to behave like C#, where there is a Program class with a static Main method.However, in the project properties, I cannot set Program.vb to be the startup object, only the forms (it is a forms application).
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Mar 23, 2011
I have an application that displays real time data. Queries are made to a MySQL database on another PC over the internet every 10 seconds to gather the most recent data.Originally I did the query within a BackgroundWorker so that the GUI is still responsive while the query is answered. However, I found that I need a timeout on the database query (as sometimes it hangs without generating an error) and couldn't do this within the background worker.
So now I'm trying to do it with threads. I have managed to run a thread to get the data.I need to understand how to run a task on the main thread when the GetDataThread is complete. If I do this using Events as shown below then Sub GetDataComplete is running as part of the GetDataThread not the Main Thread. I want to run a sub like backgroundWorker1_RunWorkerCompleted (this seems to run on the main thread).
My Main thread is called MainThread
VB
Imports System.Threading
Imports System.ComponentModel
[code]....
How can I run a task on the main thread when the GetDataThread is complete.
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Dec 15, 2009
I am using a COM library in my VB.NET app that has an asynchronous execution method and signals my application via an event when it completes. The event handler is on a different thread from the calling thread. I want to invoke another execution on the main thread when I receive the completion event. If I call directly in the event handler for another execution it starts on the new thread. How do I marshal back to the main thread. This is done in a dll not in a form.
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Mar 3, 2012
i have a background thread when it is done doing its task it notifies the main thread via a delegate sub it seems if the main thread is "busy" then the background thread hangs waiting for the main thread. if this is normal, which i assume it is my background thread, starts another thread, and this 2nd background thread makes the delegate call is this bad practice?
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Jul 14, 2011
I have written a program that performs multiple httpwebrequests. It reports in to me by writing to the console. In the past, i have used a backgroundworker for this task, but the code became ugly and bulky. Now, i use threading.thread to start the background process. However, i can't seem to find an explanation on updating the UI from the worker thread.
I've read a lot on delegates, invoke and lambda's, and i just got more confused.
Let's say, in my current program i have this line to be displayed in a textbox on my main form:
"Error reading events!"
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Feb 3, 2011
is the first time I tried to use a timer - can't understand why it doesn't work!I need to suspend the main thread for a preset time 'delaymSecs' then let the thread continue.I tried this code fragment:-
System.Timers
'(etc)
Public
[code].....
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Mar 2, 2009
Well basically I have something being done in a new thread and I would like to start a sub not in the same thread, but in the main thread. How do I do that?
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Aug 25, 2009
how to access the main ui's labels from a delegate method?
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Jan 21, 2012
It's easy to do so in objective c but I do not know how to do so in vb.net update:I know about control.invoke. But control.invoke requires a control that may change from program to program. What would be the easier way?So yes program is winform. However I need a solution that does not depend on any specific control. If that's the case actually I do not need things to be run on main thread do I?
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Nov 23, 2009
put method in main thread from background without declaring delegates
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