I am looking into using a producerconsumer threading pattern to run through a list of strings that i retrieve from a database and then am going to run powershell commands against. As the powershell commands can be quite intensive i only want to spawn 3 threads at a time and then wait for one thread to finish before doing anymore. I looked into the treadpool but it looks like it is used for more lightweight processing.
View 3 RepliesBasically I am making a proxy testing program. A user can supply a list of proxies to test. What i want to be able to do is have them be able to specify how many threads they want to run. Then have the program go through the list testing each one using the amount of threads supplied. Really not sure even where to start on this. Threadpooling?
View 3 RepliesI need two seperate lists, which every item is Integer, String, Bitmap - and one which every item is Integer, String String. However I don't know how to do this, or even where to look - I've googled for custom objects and custom object lists. What I'm trying to do is this.Custom Object1 is Integer, String, Bitmap Custom Object2 is Integer, String, String
In one thread I'll be adding items to List1(Of Object1), and processing them, and adding the results to List2(Of Object2), however I need to be able from other threads to look at the list and say only give me the items where Integer = (my thread ID), is this possible? Any help, or even links to information that would be relevant to this request would be helpful?
I have problem with multithreading.
For:
Code:
and multithreading to loop for:
Code:
How can I speed up this loop through additional threads?
I tried:
Code:
How can I do?
Im using Vb.net visual studio 2008. i have got a process(system.diagnostics.process) to be run in background and it updates the Ui thread progressbar and a label and i have worked it using backgroundworker.runworkerAsync. Now the problem is i have to work the same process for a number of time with different inputs.
The code block is :
Private Sub fnStartEvent(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.click
Dim inputFolder = Directory.GetFiles(textboxSourceFolder.text)
Dim currentNumberOfFile As Integer=1
[code]....
The problem in here is the fnStartEvent method once gets started, it calls BackgroundWorker1.runWorkerAsync process and that runs in a seperate thread and does not wait for the thread to complete and it moves to the next line of code i.e loops to the next item and it returns to same BackgroundWorker1.runWorkerAsync line and throws exception that it is already running.
Tried
1.
Private Sub fnStartEvent(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.click
Dim inputFolder = Directory.GetFiles(textboxSourceFolder.text)
Dim currentNumberOfFile As Integer=1
[code]....
But this does not updates the Ui thread used to denote progress.
2.Put the whole process inside the DoWork thread and loop for each file in there itself, but that to returns the cross thread error in progress bar updation.what is the standard procedure in executing a loop for the backgroundworker to wait for finishing as well as update the UI without blocking it.
how to add custom column to aspxgridview column using looping to get name and value of column.
here is my code behind :
Protected Sub gridSubmission_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles gridSubmission.Init
Dim colBaru As GridViewDataTextColumn = New GridViewDataTextColumn()
For i As Integer = 1 To 6
[code]....
which i used to add new column at aspxgridview.but its getting an error, "An item with the same key has already been added."second question, what property which i must use to put that code? I wanted load that code after page.load ! if i put in aspxgridview.init its was loaded before page.load.and the output it must like this :
1 2 3 4 5 6
row row row row row row
row row row row row row
[code]....
I am using a loop to update properties of each object of a set of custom objects. The routine knows which controls to update because the controls value is not empty, I don't want the routine setting the corresponding properties to nothing when the control is empty. Now I know how to do this perfectly fine with IF statements such as:
CODE:
But this feels really redundant doing that same IF block over and over for each property/control combination, I thought about creating a separate routine that takes the control as an argument and does all the repetitive IF blocks but I don't know how I could also pass an object property to tell the routine to update that particular property.
Makes the following statement about the code below:
**"The computer evaluates the loop condition in the Do...Loop statment to determine whether the loop instructions should be processed. In this case, the inputsales <> String.Empty condition compares the contenst of the input sales variable to the String.Empty value. As you know the String.Empty value represents a zero length, or empty, string if the inputsales variable is empty, the loop condition evaluates to True and the computer process the loop instructions. *If on the other hand the inputsales variable is not empty, the loop condition evaluates to false and the computer skips over the loop instructions.
Based on the code I think it is the opposite: ...that while the inputsales value is not empty it should evaluate to true and process the loop and if it is empty it should evaluate to false and skip the loop?
See below.
Option Explicit On
Option Strict On
Imports System.Globalization
[CODE]...
What is multithreading and how do i do it in vb.net?
View 2 RepliesThis is what I would like to achieve:To create a custom messagebox, with varying number of buttons with custom .Text descriptions, and other features. I intended to have a property array that would be redim-ed and have values (.Text values) set by the calling class:
[code]...
I came across this great article on creating a custom datagridview column which creates a graph-like effect in the cells of a custom datagridview column:[URL]..Does anyone know how you would edit this to format the number in the cell as a percentage? And does anyone know how you would set this up to take 0 values which do not create any graph effects at all.I have been trying to do this but keep getting errors.
View 1 RepliesI was trying to block the closing of a custom combo box popup window in my custom DataGrid. The popup window comes by pressing F4 or ALT+DOWN keys in my datagrid which is getting closed if I press the down arrow for the first time, after showing the first value in the combo box as selected. Next time onwards, if I press the F4 key and down arrow, I can move to any item in the popup window and select the item using keyboard and in that case, the popup window is not getting closed till I press the ENTER key or selection using the Mouse. Is there any specific reason for this behaviour or something is missing in my code part? [code]...
View 1 RepliesI was trying to block the closing of a custom combo box popup window in my custom DataGrid. The popup window comes by pressing F4 or ALT+DOWN keys which is getting closed if I press the down arrow for the first time after showing the first value in the combo box as selected. Next time onwards, if I press the F4 key and down arrow, I can move to any item in the popup window and select the item using keyboard and in that case, the popup window is not getting closed till I press the ENTER key or selection using the Mouse.
View 13 Replieshow to specify a custom icon for display in the toolbox window when you create your own custom control? Something other than the dreaded "gearbox" icon.
View 2 RepliesCookies to be stored in folder and on close delete the cookies The ability to watch youtube vids, view images, and play js/flash games good security, no ads?
View 6 RepliesI know I am missing the obvious. I would like a label to show how many cycles in loop are left.
[Code]...
I am constructing a program, i am new to Visual Basic, but i have past programming experience. I was wondering if anyone knew how to form a loop that could...lets say calculate the answer when two numbers are added together,and it would repeat this thousands of times, etc. And if there is a way, would it be possible to calculate the time taken to complete this loop.
View 5 RepliesI am using an Application server for calling Oracle Reports and I have a URL to call the report. When the report is called the server converts it into PDF but when report contains large data it takes a lot of time to load. I want to do in asp.net that when I call the report url it opens the PDF file and copies it into the root of my web folder. The next time when I call the URL it opens the PDF file and creates a new PDF on backend for next call. I have made this function to download file
[Code]....
In which situations we can do the multithreading and deadlock concepts. can give some examples
View 4 RepliesWhat does common data or data that's in a common, look and is treated by multithreading? I'm quite aware that acess to such data would have to be synchronized, but beyond that is it acessible?
"MODERN PROGRAMMING is deficient in elementary ways BECAUSE of problems INTRODUCED by MODERN PROGRAMMING." Me
I have a class with a background worker in it that does some tasks on a separate thread. I want to fire some events from the background worker thread to the 'main thread' of the class, so that when using this class your not obliged to go make invoke calls for every event handler your using.I'm at a loss of how to do this though. When having a similar problem in a form of usercontrol I always use Me.Invoke, but this method is not present in a class inheriting system.object.
View 1 RepliesI have a screen that checks for alerts every 30 seconds by looking up outstanding issues from a database.When there is an alert, an audio file is played depending on the alert.It takes 1-2 seconds to grab this audio file which caused an issue with global screen freezing, so I added multithreading where it plays the sound file. This seemed to work fine.However I am new to multithreading and am not sure if I'm working with it efficiently..I have simply declared the sound-playing function as a thread at the top:[code]I am unsure if starting and aborting the thread is the right way to do it. However if I suspend or make the thread sleep I would have to determine whether it has been run before.
View 18 RepliesI have read many articles on multithreading over the past few days and so far I'm fairly comfortable with how it works. I am now working on my actual application, and have come across a few design issues that I'm hoping somebody has experience with.The basic premise of the application is simple. A database filled with files names and a "converted" field that has a 1 or a 2 in it (1 for unconverted, 2 for converted). The application loops through every record where "converted" = 1, retrieve the file and convert it.
My single threaded application works fine, except its far too slow. Due to the huge amount of rows in the database (4 million+) and the time constraints on the project, I have decided to run as many threads as the hardware can allow to cut down on the timings.So, the dilemma is accessing database records and which threads should grab which record and how.
I have a function in my program that adjust sales for multiple days. Sometimes it needs to adjust up to 3 months and the tasks takes a while so I decided to split up the work between multiple threads. The way I have it working is say I need to adjust 3 months. I have the first thread adjust sales for the 1st month, the second thread adjust sales for the 2nd month and finally a third thread that will adjust sales for the 3rd month. Since all three threads are performing the same tasks except for different date range they use the same procedures. Within those procedures I make a call to the database to extract the sales for the given month. At some point it seems like the threads start to use the same SQL Data Objects because I am receiving the below error."There is already an open DataReader associated with this Command which must be closed first."Below is the first procedure that is ran by each thread up to the line where it errors out.
Private Sub Process_Adjustments(ByRef objAdjustBillCodeThreadParameters As clsAdjustBillCodeThreadParameters)
Dim cmd As SqlClient.SqlCommand
[code]....
So all three threads call this subroutine and the first thread does the data fill with no issues and then sometimes even the second thread does the data fill with no issue but then the third thread crashes and produces the above error. It seems as though the threads are sharing the same SQL Objects when all objects are local to the sub and I always thought each thread had it's own memory to work with. So I thought each thread would call the sub create it's own objects in memory, but that does not seem like what it's doing. I have other multithreading processes in my application that work perfectly fine, this is the first time I am attempting to multithread in this manner where I am using the same procedure within multiple threads.
Just thought of something that I might be doing wrong. The subroutine in question is in the same class where the threads are created. Should the subroutine be in it's own class, and therefore each instantiation of that class?
I try to use Multithreading with VB 2005. I added a Listbox to main form and i tried to fill ListBox with 2 threads. When i executed code it told me that this is unsafety operation becasuse of ListBox is created with Main(Form1) form.
Is there anybody who has such simple multithreading example with Mutex or such lock mechanism?
what is the right way of Multithreading in visual studio 2008.
View 1 RepliesI m making a project in which it check website about there status (Online / Offline) through there status code and when project is in processing it hang's until the whole line of code complete
[Code]...
I'm using the WIA Aut. Library [URL] , trying to capture photos from 5 digital cameras (Nikon D90) USB-connected to my pc. Now, I partially achieved my goal, what I do is:
- loop through the attached devices, connecting to every camera;
- fotocamera.ExecuteCommand (WIA.CommandID.wiaCommandTakePicture) ;
- other image processing operations...
Everything works fine but... the workflow is camera1 -> connect -> grab pic. => camera 2 -> connect -> grab pic. => camera 3.....
[Code]...
I'm using the WIA Aut. Library [URL] trying to capture photos from 5 digital cameras (Nikon D90) USB-connected to my pc. Now, I partially achieved my goal, what I do is:
- loop through the attached devices, connecting to every camera;
- fotocamera.ExecuteCommand (WIA.CommandID.wiaCommandTakePicture) ;
- other image processing operations...
Everything works fine but... the workflow is camera1 -> connect -> grab pic. => camera 2 -> connect -> grab pic. => camera 3.....What I'd like is to make them shoot all at the same moment (...why? well, D90 waits around 1 sec. after a shoot... 1sec * 12 cameras * 500 photo sessions.. :'( )I told myself... what's the problem? You can create "shooting-threads" while looping through the device then launch 'em all.Done.It's still in a 'serial' way... :-(((Why? is executeCommand() a synchronized method? If I madly-fast click on two 'grab pictures' button of windows XP WIA dialog it works.. Is there something about .NET multithreading I don't know?
I'm using custom serialization and when the xml is generated it's putting the class name as the root element
Example:
<MyClassName>
<MyIntendedRootNode>
<ObjectType>
[code]....
I'm invoking the serialization by calling xmlserializer.Serialize(writer,Me) so I'm sure that has something to do with it.I've tried putting XMLRoot onto the class, but I think as vb is compiling this partial class with its aspx page, it's either overwriting this property or ignoring it entirely.I'd like to just tell it to either throw away everything it has and use a different root element.