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Creating an Individual Thread for each User Control

In a separate posting, I explained how I was getting a strange graphics error with a tab page containing several User Controls:
http://forums.microsoft.com/MSDN/showpost.aspx?postid=790101&siteid=1

Each such page contains 3 to 25 such User Controls and each User Control is designed to display a Bar, Line, or Pie Chart. So there's definitely some heavy computations going on when a file is first opened.

It was suggested to me there that the main UI thread is getting bogged down and this is the cause of the problem. Thinking about this some, I decided to instantiate each User Control in its own thread. I don't have a lot of experience with threading but wrote this code to accomplish this:

// Create new thread for ChartPanel and execute it
ChartPanel chartPanel = new ChartPanel(model, qNum, question.Text);

// Monitor the special GraphInfo events that are fired by the ChartPanel controls
ChartPanel.GraphInfoEvent += new ChartPanel.GraphInfoHandler(ChartPanel_GraphInfoEvent);

// Prepare thread
Thread chartPanelThread = new Thread(new ThreadStart(chartPanel.Initiate));

// And start it
chartPanelThread.Start();

All of this code is inside a 'foreach' loop, so each ChartPanel (the user control) gets it's own thread.

My questions are these:

Does this threading code look correct?
What test could I perform inside of the ChartPanel to definitively confirm that it is running in its own thread?
I know of the rule of not changing something like a property between threads (I know how to use InvokeRequired and BeginInvoke to get around this limitation) but there is no restriction about reading a property value, is there?

Sincerely,

Robert Werner
Vancouver, BC

rwerner

rwerner wrote:

It was suggested to me there that the main UI thread is getting bogged down and this is the cause of the problem. Thinking about this some, I decided to instantiate each User Control in its own thread.

Don't do that. You can try running the computations on a separate thread to make the UI more responsive, but the controls should run on the same UI thread as the Form they are hosted on.

rwerner wrote:

I know of the rule of not changing something like a property between threads (I know how to use InvokeRequired and BeginInvoke to get around this limitation) but there is no restriction about reading a property value, is there?

Yes there is.

Mattias, C# MVP

Mattias Sjögren

reply 2