So I am currently attempting to wrap my head around create multi-threaded programs and I am currently running into an issue when using a Shared variable across multiple threads.The program is structured as follows: Public Shared IsActive as Boolean
Main Thread = GUISets the Value of IsActive through a Button ControlTwo Worker ThreadsBoth threads are while loops that read the IsActive Boolean Ex:While IsActive = True Do Work End WhileHowever when I change the value of IsActive from the Main Thread it causes the worker threads to stop (ThreadState = 16).
I have been reading that I have to synchronize/lock shared resources and have tried SyncLock and Monitor methods without success (it is entirely possible I am not using the above correctly, so If someone could provide proper examples for the above situation using the mentioned methods please share them).
I am trying to add shared members in derived classes and use that values in base classes...
I have base
class DBLayer public shared function GetDetail(byval UIN as integer) dim StrSql = string.format("select * from {0} where uin = {1}", tablename, uin) end function end class
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currently there is error using the tablename variable of derived class in base class but i want to use it i dun know other techniques if other solutions are better then u can post it or u can say how can i make it work? confused...
I have a problem with inherited classes. Have a look at the following VB.NET 2.0 / VS 2005 code:
MustInherit Class templateclass Public Shared x As String End Class Class child1
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The templateclass has a shared variable x which is of course inherited by the child classes. But I wonder that all child classes share only one x! Until now I thought that shared variables are only shared among the instances of a class, not among all childs. This is very annoying because I have a base class which I need in two slightly different versions and they should not "share the shared" variables. And because the classes have a lot of shared variables, shadowing each in the childs would be very..
I'm trying to split some prior crafted code into a DLL. It's a simple logger system.There are a few things that need to be shared with the main form in the project, so I set them up as a shared variable, but I don't use shared stuff often, and I worry it will cause variable conflicts regarding scope. I figured I would make a post here about it and see if someone can explain what I don't fully understand.Since this is a logger it will be used a couple of places. Other DLLs that need logging may reference it through a instanced object and project reference. My main form will also have an instanced object and a reference to the logger libary.Since one of my properties is a connection string and it's shared, does this mean that a instance of my logger class inside a DLL will have the same shared values as a instance on my main UI form? Or will the fact that the instance is inside of a DLL provide the scope boundary I need?
I've been looking at threading to make my webapplications more responsive. I've found out how to thread a sub that takes no variables and doesn't return anything, but I can't find out how to achieve this for a function that takes variables and returns something. here is an example
I was reviewing the MSDN documentation on VB.Net's little-used Static keyword for local variables. My question is not about how Static works (I personally plan to avoid using it as it seems like it could cause grief to future programmers who don't notice the side-effects.) My question is about this statement in the docs:[code]So can anyone interpret the above statement for me in a way that makes sense? Or is this a bug in the documentation? It's been there since the VS 2005 version of the docs and is still present in the Visual Studio 11 version.
I am making a small application in which i have added a class module and a window forms in vb.net. i want to acess the shared variables and mathods of class without making any object.
basically i was wondering if we could inherit shared variables but restrict its scope to only that of the class itself.
Class A Public Shared shared_variable as Boolean = true End Class
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when i do this A.shared_variable = False, B's shared_variable also becomes false. how do i stop this?i cannot remove the Shared keyword because shared_variable should be able to be accessed without an instance of the class?
I've been doing some reading on garbage collection in .NET and I was hoping for some clarification. So, as I understand it if I declare a public shared class variable, the GC will never get rid of it. Is this correct?Also, what then of private variables? Take the following example:
public class myClass private shared myString As String public sub ChangeString(newString As String)
I have created a public shared subroutine in a class file in asp.net 2 (vb.net) web site app_folder.The subroutine retrives some values from a sql database via an sql query and assigns the datareader field values to several variables The problem is I can't seem to assign the variables from the subroutine to the variables and textbox controls in the asp.net page I am calling the subroutine from. The textbox text value just appear blank.By the way, if I response.write the variables in the subroutine they appear populated by the sql data reader.
Well I am a new to VB.NET, converting a legacy system to .NET world. Recently I have been reviewing the already existing code since I joined the project quite late in the team. I find that there are many shared functions (not shared class) inside many classes. I doubt this may create some problem if two requests ( i.e two different HTTP request to the same method as it's a WCF application, of course exposed methods are not shared but internally called methods are shared) comes to the same shared method and both the calls to the method may have different method parameters/arguments, overwriting each other's arguments. In short, if shared method has a list of arguments which is going to be processed, is there any chance of inconsistencies in the light of multiple access to the shared method via two http requests.
give me a good resource that explains the difference between a Private, Public, Shared Functions/Sub/Variables? I normally use Public for Subs/Functions inside of Modules I call from other parts of the program. But I'd like to get more of an understanding of how and when to use them. I want as little as impact to a system that is running my programs as possible, so i guess the key here is I'm trying to just get more proficient in my coding.
I came across a number of new Private Shared variables (of type Hashtables(Of String), initialized in the declaration) added to a partial class for a very large (DataContext-derived) class. This seems sensible to me in one sense because they never change, and making these shared variables ensures that they won't get re-initialized every time a function is called. However, these variables are only used within the scope of one function in the class, and I fear the private namespace of this DataContext-derived class is getting rather polluted, and having these sorts of things exposed at such a high level might be confusing to others reading the code in the future.
Would there be negative performance impact to making these local variables within the function where they are used, or is there some better way to handle this? Basically we are using these 3 hashtables to determine whether anything within particular subsets of properties changed (using GetModifiedMembers and then using the Overlaps function of the hashset to see if any of the modified members correspond to members we care about).
Edit: I caved and took the time to write my own test program, which confirmed that there is a cost to using local variables (which I assume applies generally to all cases -- I doubt there's any case where a shared variable would be slower unless using the shared variable requires some additional logic to do so properly): [Code]
So in this particular case, using the local variable costs about 200%. But in most cases (including my own), the time is probably negligible compared to the overall task. So I guess the question now becomes, how do people generally feel about improving code maintainability at the cost of negligible but known performance impacts?
I am writing some code that uses fixed regexs to search strings and pattern match. Its simple stuff, but I want to improve regex performance with compiling (its a high traffic website). I was thinking of compiling the regex and putting it in a Shared (static) variable inside a class. Something like this:
I've found out that if two instances of an SSRS report run at the same time, any Code variables declared at the class level (not inside a function) can collide. I suspect this may be the cause of our report failures and I'm working up a potential fix.The reason we're using the Code portion of SSRS at all is for things like custom group and page header calculation. The code is called from expressions in TextBoxes and returns what the current label should be. The code needs to maintain state to remember what the last header value was in order return it when unknown or to store the new header value for reuse
I have a problem. I'm creating a new thread, which should do some stuff and update a text box. But, when I test my program, the main (UI) thread is doing all the job, even though I declared and started a new thread.
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I even made another thread for testing purposes, but it was the same.
I've been raking my brain for quite some time on this. Is there any way with VB.NET that I can use multiple IP's in one instance of a program? For example, I want to be able to navigate to a web page 10 times at once, with each one using a different IP. I want them to be parallel (multi-threaded) rather than going sequentially. Going sequentially, I could just do the action, change the IP, do the action, change the IP.
I have a button and when it's clicked a HTTP request is sent out to a website to do a few things, but because its got to load the external resources it makes the interface frozen. I've moved the HTTP onto another thread using the follow
VB.NET Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim Thread1 As New System.Threading.Thread(AddressOf check_accounts)
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When i want to update a label that is on my main form (from the check_accounts sub). I know that isn't the right way, but i have no idea what the right way is. All the documentation i can find is very (excuse me for this) nerdy and really doesn't offer much insight on how to incorporate it into a project.
I want to be able to have a numericupdown box that can let the user change the amount of threads they want to use. I assume more threads allow the http requests to be done faster and at the same time?Also if i wanted to pause the HTTP requests, would the best method to use be pausing the thread?
I have an application that performs a lot of busy work. All of the work is performed using a BackgroundWorker and the point of execution is the DoWork Event of the BackgroundWorker.On the UI thread, before the workload begins, I display a PictureBox that contains an animated GIF that illustrates progress; for the most part this works fine and the UI thread is not paused or slowed while the BackgroundWorker does its job. There is however, one instance where the UI thread is impacted by the work being done and it defeats the whole purpose of putting this work in a separate thread. In this application, the user must wait until the work completes before they can move to the next step, so my sole reason for moving this all to a BackgroundWorker was so that I could display a smooth, uninterrupted progress indicator on the UI thread while this work was being done, so that the user could see that something was happening.
The case where the work being done is impacting the UI thread (pausing/delaying the PictureBox animation) deals with a referenced COM object.
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All of the COM object event handlers and subsequent functions are appropriately using Delegates, but I am not sure why the ProcessFiles method would cause the UI thread to hang while the work completes; I thought that was the whole purpose of the BackgroundWorker.
I am working on an application that is taking pretty long to execute. I started playing with mutli-threading and it seems to have greatly sped up my app. Problem is that threads are still executing and the rest of the code executes before the threads finish. Here is my
to some server via an UdpClient. However, I need to make sure that all commands send are separated by a 1 second delay. If there is no delay, two commands send within this 1 second timespan will not be received both; only the first or the second command will get through.he commands are sent in a background thread at the moment, because it might take some time before the command is sent. I keep looping until the command has been sent, like this:
vb.net Public Sub Send(command As String) Dim bytes = Me.GetCommandBytes(command)
I am getting error when I am putting my sendmail function into other thread. But without threading the message was sent successfully. I am getting error in this part when sending using thread. mail.Body = EmailBody.DocumentText It say: Specified cast is not valid. Here is my code for sending email EmailBody is a webbrowser in Desing MOde ON
I'm having some issues with parsing a lot of information into controls using winforms. I've tried adding threads/backgroundworkers, but they don't seem to work properly. To avoid the cross-thread exception, I had to add an invocation checker:If Me.InvokeRequired Then Me.Invoke(New MethodInvoker(AddressOf ParseSub()))This just freezes the form as it would without threading, but without the invoke checker I get cross thread exceptions because information from one thread is trying to be sent to another.
