Solved

Need help with VB.net application. Sometime, unable to get the UI/Main thread when trying to check with invoke

Posted on 2016-09-14
2
22 Views
Last Modified: 2016-10-04
Hi
I have a multi threading application, in which I am trying to use UI/Main thread to display data.
Here is what I am doing
1. I am getting quote from an API in a thread (each time a new thread is created)
2. I am going to main thread using  "If Me.InvokeRequired"
3. Display information on screen
4. Create a new thread for further processing

I can further explain this with code.
I am also getting the error "A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll"

I am unable to find why I am not able to get UI thread though I am using the following code to check the UI. It some time works and some time it does not work. Some time it goes to UI thread with invoke and sometime it does take the condition and comes to display function with worker thread.

The code is as follow (This is a cut down version)

If Me.InvokeRequired Then
           Dim d As New SetQuoteTempCallback(AddressOf SetQuoteTemp)
            Me.BeginInvoke(d, New Object() {[symbol_id], [bidprice], [askprice]})
Else
           displaySymbolInfoOnChart(symbol_id, bidprice, askprice)
end if
0
Comment
Question by:Inam Alvi
  • 2
2 Comments
 
LVL 33

Accepted Solution

by:
sarabande earned 500 total points (awarded by participants)
ID: 41799254
generally, if you call from a worker thread to ui thread, you have to use windows messaging. you never may call functions of a different thread context directly.

so the general concept is to create an object where the results to display were stored. then post a  user message to the main thread passing a handle to the result object as argument. the main thread would have an event handler for the message and displays the results.

Sara
0
 
LVL 33

Expert Comment

by:sarabande
ID: 41827718
The question was abandoned without further response but has a proved solution.

Sara
0

Featured Post

Is Your AD Toolbox Looking More Like a Toybox?

Managing Active Directory can get complicated.  Often, the native tools for managing AD are just not up to the task.  The largest Active Directory installations in the world have relied on one tool to manage their day-to-day administration tasks: Hyena. Start your trial today.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Introduction Hi all and welcome to my first article on Experts Exchange. A while ago, someone asked me if i could do some tutorials on object oriented programming. I decided to do them on C#. Now you may ask me, why's that? Well, one of the re…
Performance in games development is paramount: every microsecond counts to be able to do everything in less than 33ms (aiming at 16ms). C# foreach statement is one of the worst performance killers, and here I explain why.
This Micro Tutorial hows how you can integrate  Mac OSX to a Windows Active Directory Domain. Apple has made it easy to allow users to bind their macs to a windows domain with relative ease. The following video show how to bind OSX Mavericks to …
Email security requires an ever evolving service that stays up to date with counter-evolving threats. The Email Laundry perform Research and Development to ensure their email security service evolves faster than cyber criminals. We apply our Threat…

772 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question