.net - ASP.NET Two Threads, One Result?
Sep 14, 2011
I need to run TWO Threads in a web application, .NET. 3.5 Both methods MakeRedCars and MakeBlueCars need to run at the same time as both take 5 seconds. I have tried many example codes with very bad results. I dont need anymore than 2 threads. The main issue I am having is knowing how to wait till they are finished and also how to store the results from each.Each of the Methods do different things, one is a web request, one is a sql call.
Both methods return a list of(cars) for example do:
carList.addrange(MakeRedCars())
carList.addrange(MakeBlueCars())
for each car in carlist<br>
response.write(car.colour + "<r>")
next
I have implemented the answered below and with empty objects all works well, as soon as you hook in a database call that returns the data/objects studio does a JIT and crashes.
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Oct 19, 2011
I just had a new, last-minute idea on to take on a task, so I am running to StackExchange for quick help.
What I want to do is execute a series of methods right in a row, each in their own threads. I want the application to wait until all of these threads are completed, after which the program will resume. It also has to use managed threading (thread pool).
What quick examples could you provide to help me along the way? If it's too complex, what things should I know about so that I can Google it on my own?
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Dec 30, 2009
I have a main thread which is designed to be a batch processor - it spawns a series of 'child' threads from a loop (which can vary in terms of the no of items) - see below
[Code]...
However, each of the 'child' threads could take anywhere from milliseconds to about a minute to process - depending on the complexity of each calculation. There may also be a large number of child threads - e.g 100s. Creating large numbers of child threads is not efficient. I therefore want some way to effectively queue each child thread (and cancel if the process is taking too long to complete). Autoevents seems like one way of doing this, but the only examples I can find seem to assume there are two different processes on seperate threads, not one process being repeated.
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Dec 10, 2010
I am currently having a headache on how to solve this problem that i am facing. here is the situation: I have a combobox and a list box on the main form. The combobox will get the data from the ms access database. In the database, i have the details of a person's IC, Name and DOB say for eg on one entry I have D215311523C,SHAWN,13/04/1987 So now, my combobox on form load will show the list of dates in the database to allow the user to search base on the date itself by clicking on the selected date. So when the user clicks on the particular date say 13/04/1987, people in the database whose birthday is 13/04/1987 will be shown on the listbox.Meaning to say if i have 3 entries whose dates are the same 13/04/1987, 3 entries will appear. If there is only two entry, then two results will be shown. But now, when i do a single click on the date, one result will be shown. That is correct. But the problem is when i click on the same date again, three of the same results will be shown on the list box. that is it will display : 13/04/1987 13/04/1987 13/04/1987 which is not the case. Then it will show more duplicates of the same results if i click more times on the same date which should not be the case.
Dim n As Integer
Dim numbers() As Integer
Dim StartFrom As Integer
Dim EndAt As Integer
[code].....
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Sep 25, 2010
I am using a datagrid in my where i am having four columns. In first column the parameter values are entered and in the second column measured value is entered and in third column the nominal value is entered.Inthe fourth column the result is displayed by subtracting the measured value and nominal values. I am doing this calculation in Datagrid cell validated event. What i want is,there will be many rows in the grid,when typing the value in the third column the corresponding result will be displayedin the rowof theresult column,save button will be displayed while the form loads,when the calculate part is completed that is there should not any cell of the resut column empty then i should enable the save butto.
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Oct 14, 2009
I am encountering the following issue So i have a device that sends stuff at the serial port, i then parse it and put it into an array of bytes like that:
Dim HCI_Command_Rcvd_Byte() As Byte All good till here What i wanna do is make an array and put this result every time the serial port gives me a new result, for example:
[Code]...
Basically what i wanna do is let the port parse the messages, fill in the array with the result at an empty spot in this array and then i will have a separate thread that will look in into this array in each non empty space and after it looks into the non empty space it will use or discard the info and also mark this space as empty (after it checked)
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Apr 16, 2010
I just read about DataSet in VB.NET, it uses disconnected concept. My question is: if my apps has "List All" button that query data from 1 table in the database, and that table has "very very very" many rows, so my DataSet will be filled with those data and eat up memory. Can I limit the data that being put to the DataSet from that query? But I want to be able to retrieve the next data from the same query if the user want to see it?
For example:
I have 1000 rows in my database, and i query all of them. But I just want 200 rows being inserted to my DataSet, but if the user want to see rows number 201 and so on, I want to be able to retrieve the next 200 rows, and so on. So it just like cutting those data into a group of 200 rows. Can I do this with the concept of "disconnected" of the DataSet?
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Jun 21, 2011
I have set up a method in vb.net and in xcode for encrypting a string using as far as i can tell the same parameters for an AES encryption.I've looked all over the place but cannot find information on whether they use the same encryption algorithm and settings.
this is the vb.net code:
Dim encryptAES As New AesCryptoServiceProvider()
Dim encoding As New UTF8Encoding()
Dim encryptor As ICryptoTransform
encryptAES.Key = encoding.GetBytes("12345678901234567890123456789032")
encryptAES.IV = encoding.GetBytes("1234567890123416")
encryptAES.Mode = CipherMode.CBC
[Code]...
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Jan 28, 2011
I can only run "so many" threads concurretnly, a notion which I have seen elsewhere.As a threading novoice, how can I determine the maximum number of threads to use? Or is this a "how long is a piece of string" question? What does it depends on? Hardware config or what?
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Apr 18, 2010
it would be best if I just copy and pasted the code (it's very trivial).
Private Sub Main() Handles MyBase.Shown
timer.Interval = 10
timer.Enabled = True
End Sub
[code]....
An exception, "The object is currently in use elsewhere", is raised during the tick event.
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Oct 25, 2010
I am having an issue where I need to implement a type of thread scheduling... I'm looking to implement a list of tasks, each with a set time that they need to execute, and after the time is up they will execute the respective code that goes with that task. I would use a timer based solution, however, I don't think that it would be very efficient. There will be a very large list of tasks, some of which need to be executed within seconds of being placed in the list.
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Jun 10, 2010
I have 2 thread.One that put some data inside a list?the second that take out these data from the same list.what is the best "list" that allows one thread to put something inside and another one that take stuff out>
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Nov 7, 2010
My application generates some background threads to perform some slow jobs (a cycle of ask for a long process to a server - wait - download the result).
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Feb 25, 2009
I'm having a bit of an issue killing threads off and resetting my form. After starting the threads, everything runs fine. When I want to cancel the threads, the threads are all killed off "properly" using the Abortable Thread Pool, but how do I know that all the threads are dead? I've tried using both GetAvailableThreads and GetMinThreads compared against the thread count that should be running if they're all killed off, but I can't seem to get it to work. The only time I can get the GetAvailableThreads to return the "correct" number is if I freeze one thread and kill off the rest.
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May 28, 2010
I have a GUI that is running for a form, let's call it Class xWindow. It has finished processing data and is simply waiting for the user to press a button, i.e. the main thread has nothing to do. Just before it finished processing, it kicked started something that has a callback function which occurs in a new thread (e.g. a system timer or a Bonjour callback to say that a service has been found on a port). This callback occurs within the xWindow class.
[Code]....
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Dec 22, 2010
Suppose I have created 70 "rule-finder" objects, and I want to run each one on data.This is a time-consuming process.The new computers with the I7 chip can run 7 processes in parallel, and so I was thinking of running 7 threads at a time. Asone thread ends, I would add another, until all 70 objects are used. When the last rule-finder has completed, I would resume the main course of the program.
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Jun 1, 2009
how can I let two threads communicate with each other by using VB.net?
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Jan 25, 2010
I currently have a program that runs several "intense" queries. I added a textbox and presented status updates when a query was starting, eding and how many were left. This would suite my need, but the textbox doesn't actually display anything until all the queries are finished. It then displays all the updates at once. I'm assuming updating the textbox in another thread would solve this issue, and that is where I am lost. How can I use a thread that receives a message from the main form running the query and have it display it in the textbox?
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Feb 25, 2009
I'm making a Tabbed Web Browser, and I need favorites to add to this web browser, I was searching this forum for answers on how to do it and I ran into some threads tlaking about XML and how they are easily controlled, yet a little more complex. How do I do this? Where do I start?
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Jan 23, 2011
Take a look at the code below. Here I create a thread, set its name, and start it:
Private Sub fileCreated(sender As Object, e As FileSystemEventArgs)
Dim processFileThread As Thread = New Thread(AddressOf fileCreatedHelper)
processFileThread.Name = e.FullPath
processFileThread.Start()
End Sub
This is the sub that is the thread: Private Sub fileCreatedHelper()
[Code]...
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Aug 17, 2011
I have a threading problem when it comes to updating the gui from the thread.
In my main function I have the following:
Private Sub StartThreads(Optional OrgName As String = "")
Dim blnMonitorEntered As Boolean = False
[Code]...
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Jan 4, 2011
In a .NET 3.5 Winforms app, after a user provides a username and password, I set a custom principal in the CurrentPrincipal property like this:My.User.CurrentPrincipal = Service.GetPrincipal(username)This is done in a method that is called using Invoke, because the originating thread is not the UI thread:Invoke(New Action(AddressOf doLogin))But when I click on a button in the Winforms application, the CurrentPrincipal property has been reverted to its default, the current Windows user.Dim lPrincipal = My.User.CurrentPrincipal ' not my custom principalApparently, using Invoke while setting the principal does not solve the problem. Is there another way to set the CurrentPrincipal property for all threads in the application?
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Jun 26, 2011
i have this code which i run with queued 10,000, even when a max of 50 is set but the threadpool counts goes to high.
Public Sub DoWork(ByVal objItem As Object)
Dim objUrl as String = DirectCast(objItem, string)
Try
If objUrl Is Nothing Then
[code]....
EDIT:i use a this code to check the number of runing threads each second
Sub Timer1Tick(sender As Object, e As EventArgs)
tsslthreads.Text=string.Format ("Threads: {0}", Process.GetCurrentProcess().Threads.Count)
End Sub
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Sep 28, 2010
I have 2 threads in my Program. Here is code for both of them
Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
[Code]...
StartReceiving is working fine but StartWriting is called only once and that msgbox in startWriting is never called, any suggestions on this
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Jun 16, 2012
My question is to add two numbers up using threads or multithreading. Here is what I have:
Module Module1
Sub ThreadA()
Dim I As Integer[code].....
Is there a way I can use this somehow to add two numbers up?
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Oct 27, 2010
In my Winforms application, i've got a form and an associated business layer class. All controls are bound. When i click a button i call a method on the class which then starts a background worker and returns. The background worker does some processing and finishes.
The problem i'm having is that i'm using a label to display any error messages generated by this background worker, which is fine but after a set time i want to clear the label, so for that i'm using a timer (on the business layer class), which, when it fires, is on a different thread and thus should not update the property that the label is bound to Whats the best way to do update the label? -- Should i be using a delegate to update the property value, if so how do i invoke it?Note i'm also having a problem with getting the databinding of the visible property on this label to work.
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Oct 18, 2011
In VB.net, I tested concatenating 100k strings and found out one thread alone did it in 23 milliseconds. Two threads (each concatenating 50k) then joining the two at the end took 30 milliseconds. Performance wise, it didn't seem beneficial to utilize multiple threads when dealing with only 100k concatenations. Then I tried 3 million string concatenations and two threads each handling 1.5MM always demolished one thread handling all 3 million. I imagine at some point using 3 threads becomes beneficial, then 4, and so on. Is there a more efficient way to concatenate millions of strings in .NET?
fyi, this is the code I wrote:
Imports System.Text
Imports System.Threading
Imports System.IO
[code]....
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Jan 18, 2012
My scenario is that I have a Windows service running as SYSTEM. That means no network rights by default. I want to copy a file from server A and server B. Both require different Credentials.Normally, I use Impersonation on one thread to access another server [URL]. The problem is that one thread can only impersonate as one user. And I need to access server B as well.So, I wonder about the best way to copy between two threads. I am interested in doing this in memory, for speed and I do not want to save a file locally on disk in between.
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May 4, 2010
this is sumit from Larsen & Toubro Mumbai-India,I am writing a code for some sort of software in which execution of some code is required as soon as my software receive a barcode from barcode scanner (serial input). Now through datareceived event handler i am able to read the barcode but after that i am not able to send this barcode to any textbox or even i am not able to start any other event like performclick to any button or anything. I am getting an exception as cross linking of threads not possible. please refer to the image and give me the solution asap.
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Jun 7, 2011
I recently began working on an application that was built by someone that is no longer available. This application is filling an excel file, but I can not find ANY code that uses excel. There aren't even any references to excel interops. My thought is that this a multi-threaded application and I can't see what is going on behind the scenes. I tried watching the processes in the task manager, but found nothing.I've never worked with threads before, and do not even know where to begin. Debugging the program with breakpoints at multiple locations does not show me any of these other threads. Anyone have an idea on how to find/debug threads of a program?
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