i have one project with multiples web services so i created various singleton class thinking in
performance. now i think create one singleton class and that have the instances of my webservices
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I'm adding multi-threading facilities for the first time. I have a function that is wrapped to be run in a separated thread. This function retrieves data (text) from a combobox and it works for sure without multi-threading.
When I call it as multi-threaded, I get the following error when I try to retrieve the data from the cmobobox: Cross-thread operation not valid: Control 'cmb1stBL' accessed from a thread other than the thread it was created on.
It looks like a restriction of thread-safety... I assume that the child thread cannot read from his parent, to make sure that he doesn't change his parent data. So how can I read the data from the combobox? Should I read the comoboxbox data before calling the child thread?
I have a need to build an app that will access about 10 websites and pass data to them, etc.I've read about something called multi-threading when searching Google. I've also seen people say that they use multiple browsers.Which route is better to use? I figure if you have to do some sort of multi-threading that you would access a single browser?
View 2 RepliesI have a need to build an app that will access about 10 websites and pass data to them, etc.I've read about something called multi-threading when searching Google. I've also seen people say that they use multiple browsers.Which route is better to use? I figure if you have to do some sort of multi-threading that you would access a single browser?Not sure which way I should approach this app.
View 2 RepliesI need to be able to call a C++ dll that takes a long time (possibly infinte, it relies on user input)to execute. Im calling this through VB. My VB GUI freezes up when this happens, and I would like to keep the GUI responsive, so that the user can stop this possibly infinte loop. A bit of background, the C++ is trying to keep score on a snooker table using a webcam, and while the VB scoreboard updates easily, I would like to script it so that the analysis is almost continuous, while still allowing the user to interact. Currently the project requires the user to press a button to start the shot analysis, but it would be preferable if the program scripted itself. I have only realised this problem now and the deadline is very soon.
Update: Our lecturer suggested an option to solve the problem, but it would appear that most options here and the one he suggested will not work for us as the processing time required for the webcam image capture is too great to handle due to hardware constraints.
I really need assistance for this multiple problem am facing here. Let me take you to my hell: I've got three tables in my database that are:
1) tbAthlete (athleteID, nationID, gameID, fname, lname)
2)tbNation (nationID, nation)
3)tbGame (gameID,game)
I connected the database to vb and created a (form1) based on a query that use all fields except IDs. that form1 is just good as displaying and navigating throug records. Now i wanted to link that form1 to another form(2) which will allow me to update and add new record. in the form2, country and game need to be combobox as there is no need to enter new record for them. so when adding new record, only "tbAthlete" table get affected. form1 works as excpected. how do i go for the form2
SMS Multi Threading
View 4 RepliesI have a list box on a form and it works fine for what I want to do.I am wanting to edit items on the form, this means populating the listbox and then selecting the relevant items.
My listbox contains a list of item sizes, i want to select the sizes which belong to the item being edited.
can someone give me some pointers.I tried me.lstItemSizes.SetSelected(i,true) but this only works for a single item.
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im just about to start a project for college and i have to make a multi track recorder , basically a recorder that records up to 16 wav tracks and plays them back simultaneously . It must have thye ability to change the input, input level, volume levels Panning etc.
Its a large request i know but i really need some ive only had 1 year of basic vb.net programming, i know a small amount about WPF.Oh and also it will be VERY Graophically rich and will look like a mixing desk so any extra requirements i will need to use images as sliders etc?
I know .Net and C# pretty well, but never even looked at VB.My problem is: our Win32 COM library is used by a number of clients, and we see that the number of failures is higher for those who use the library from VB (both VB and VB.NET) than for those who use C++, C# or Delphi. One thing about our library is that it is supposed to be used from one thread only - can some threading magic by VB be the cause of failures?
Clients tell us the do not create any extra threads on their own.
Ive got a jagged multi dimensional array, how to work out the length of a single row of the array so;
My array is ;
CODE:
And i wish how to find the length of this;
CODE:
i have 3 multi textbox's .. and one button. it should lookup for the strings or numbers that available in the first textbox and not available in the second each string or number in new line.. and put it in the third on button click::
for example the user writes 200 name in the first textbox and 100 name in the second... and he click the button... it should appear the names that are not Available
so ..how to select a Specific line in the multi textbox and get the text from it?
I'm creating a password hash recovery tool that uses brute force. I have the brute force algorithm run in a background worker. It all works, but some similar apps I tried out have performance ~100x bigger then my app. (mine does 50k keys/second, some others do 5m keys/second or more.)I realize this is partly caused by using a .Net language, but I suspect there are ways to significantly speed up the brute force. A lot of ppl say I should use multi threading, but how is this done in practice? Splitting up the passwords to check would slow down my app I think.
View 1 RepliesI have a button click event and inside I do a lot of work. While I am doing this work (not from the UI project) I want to send messages to the UI to display to the user.
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and inside DoMyWork which is in another assembly i can call SendMessage which writes to the textbox. The messages will only display though when DoMyWork is complete. How can I update TextBox1.Text on the fly without putting DoMyWork on a BackGround thread or do i have to put it on a BackGround thread? I do actually want to block the user from doing anything while DoMyWork is running
I have a system where I would like to show a warning to a user if there try and edit a record that is currently been edited. If this is the case the user will not be able to save the record but only view it.I have an idea of using some kind of class to monitor the activity of records been edited etc but this seams a little over kill. My other concern is that what if the browser crashes or there shut their computer down on how this will effect the state of the page.
Another thought was to use last updated time stamp but this also looks a no go because the way records are been updated? how I could implement something like this. No code is necessary.based on the comments I have added these additional details.database is SQL server 2008 asp.net 3.5 one record could be many parts of the database for instance, the booking table session table and a row in the interrupter table.the user will look at a list of sessions that need booking select a booking and fill out a booking form to make the booking. Want to stop is someone else trying to do the same booking at the same time or while someone else is doing the booking.
I know there are many cases when it's best to multi thread an application but when is it best to multi thread a .net web Application?
View 5 Replies[code]'when i enter 'Q' key output(textbox1.text) = 'qQ' how Show Q only''' 'and how i can set multi shortkey output = CTRL+TAB+CAPS LOCK,and bla bla , and send to Timer1' End Sub.[code]
View 2 RepliesFirst, I don't fully understand why VBA can have a multi column combobox but full VB doesn't? What purpose does it serve to only have a drop down list of text strings? I know there is an index property, but what if the items in the drop down can't logically be associated with an index value?
Anyways, here is my problem. I have an enumeration value that I want to add to a combobox. I have the code to go through and add the text of each enumeration value to a combobox. This is fine for enumerations whose values progress in order from 0-whatever. However, I have some enumerations whose values are, for example[code]...
Private Sub ListBox1_DragDrop(stuf) Handles ListBox1.DragDrop
If e.Data.GetDataPresent(DataFormats.FileDrop) Then
Dim Fs() As String
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i want make picture slide show by using Picture box . who navigating with Next or Previos Button how todo?
View 2 RepliesI've written a simple WAV player in VB 2010 - a Windows Form App with no menus. I'm trying to create a hotkey, like CTRL-D that would make a text box visible. Typing the correct password in the box will expand the form and show some Administrative functions. I'm having issues creating the hotkey with more than one key.I've got the following code, but it does not work. I do have KeyPreview set to True.
Private Sub _KeyDown(sender As Object, e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown
If e.KeyCode = Keys.Control And e.KeyCode = Keys.D Then
txtPWD.Visible = True
I've also tried
If e.Keycode = Keys.ControlKey & e.KeyCode = Keys.D
and many other variations including changing to ALT and SHIFT but nothing seems to work. If I remove one of the Keys, it works just fine.
I have a ML TextBox that gets data added into it every 5 seconds. It has a Vertical ScrollBar on the textbox.My problem is that I want to always see the latest data entered but the scroll keeps readjusting to show me the first data entered.
View 2 RepliesGoogled this for the last hour and can't seem to find what I am looking for. for example have firefox open twice, and it has one process, firefox.exe the following code is run:
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I had followed the Example on mulit-thread in MSDN, but add a loop in my implementation. But seems like the multi-thread is not working.
Private
Sub
SboE_Start_Btn_Click(ByVal
sender As
System.Object,
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I'm experiencing an error which complexity and way to approach I can't quite understand.. It looks like two threads not able to work simultaneously.The first thread is the normal program thread, and the problem occurs when the user clicks a button. This sends some messages through a method (PlaceOrder) of an API library object. This method is called 2-3 times in a loop. Handlers have also been added (on program startup) to receive callbacks on events raised by that object, and this is the 2nd thread that contributes to the error.
The error seems to occur when the PlaceOrder method is called while receiving an event from this same object.The result is that the UI freezes. I can trace the error in two places. If I trace the first thread (which is the initial program thread); the freeze occurs when reaching the lock(this) line, in the API-object class. If I trace the callback event, the handlers of this event try to invoke a RichTextBox on the form, and the freeze occurs on the line <RichTextBox>.Invoke(....), as indicated below.
The thing is that when pushing the button, there is a loop which calls the method of the API-object 2-3 times. And the first time succeeds, but the 2nd time it seems to crash in some way with the callback. It would be nice if I had made some silly mistake with the invoke code, but I don't think I have, as it updates fine prior to the error.. I'm not sure, but it may be relevant that it's in fact the same object, so early in my program I add this event listener (which is the one that updates the RichTextBox):
AddHandler ibclient.Error, New EventHandler(Of ErrorEventArgs)(AddressOf client_Error)
..while later, related to the freeze, I have:
ibClient.PlaceOrder(....)
But I'm handling a lot of calls forth and back other than these, and haven't experienced any problem before.it doesn't give any exception or error message, it just freezes.The invoke stuff in the form code, which should be as per trusted examples: (Freeze occurs at blue highlight)
Private Delegate Sub SetRichTextBoxInvoker(ByVal message As String)
Private Sub OnLogUpdate(ByVal message As String)
If Me.rtbTwsMessages.InvokeRequired Then[code]........
I made a simple Form1, with Text.Box1 (starting value=1) and Text.Box2 (starting value = 100000), as shown in the attachment: I wanted that, when the Form loads,value of Text.Box1 keeps on increasing by 2 and value of Text.Box2 keeps on
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One of our products consists of two different services:
- main service that launched at the startup of Wndows
- GUI that launched manualy when needed
GUI is representing data from main service.Main service starts X amount of threads that do some work and gether data.Some minor data and adresses to threads are stored in chache memory, so that GUI will have access to them.Everything works fine in 99% cases, but in some rare cases GUI do not display any data when used on machines with multiple processors (not milti-core). My guess is that it can't access the memory -> probably OS "decided" to run main service on one processor and GUI on another one.Is there any way to access the memory alocated for one processor from the service that runs on another processor?Or is there simple and secure way (same application will be also runing on single processor machines) to specify both services to run on the same processor?
I'm trying to run a multi-threaded console app in VB and am having thread cross-over. Basically I want to run 5 threads, have them continually access a queue, process, and repeat until there's nothing left. When all threads have processed I want them to do something else.I'm attempting to use SyncLock to prevent multiple threads from accessing but it does not seem to be working.[code]
View 3 RepliesI have a question regarding the synchronization in multi threading.
I have a function called send which i am calling in a for loop for every data row.
This function creates threads to send emails to different people.
Public Sub send(ByVal Conn As Data.DataRow, ByVal job As Data.DataRow)
MyThread = New Thread(AddressOf Me.start)
MyThread.Start()
End Sub
But every thread created is writing to a log file at different points of time. So, there are very high chances that 2 threads write to the same file at the same time. So, do i need to use any kind of synchronization mechanisms here ? or is it fine without them ?
I m trying to use multi code file that contains events, functions etc...I have a form that named Form1.vb, code file Tab1Codes.vb and a class ClassUsers.vb.Form1 is containing a function like:
Public Sub Tab1ShowHideFunction()
'some codes....
End Sub