The calling thread cannot access this object because a different thread owns it" exception

Question

Hi I am first time working on Threads not sure If I am doing correct I am getting Error saying :

   private void ImportProductStatsButtonClick(object sender, EventArgs e)
    {
        // Get the currently selected manufacturer from the combo box
        var selected = comboBoxCorporation.SelectedItem;
        buttonProductStatsAndRetailerStats.Enabled = false;
        buttonSummariseRetailerStats.Enabled = false;
        buttonSummariseProductStats.Enabled = false;
       // Do we have one?
        if (selected != null)
        {
            // Extract the combo record
            var corporation = (ComboBoxCorporrationItem)selected;

            // Do we have one?
            if (corporation.Corporation != null)
            {
                // yes
                // Make this on a seperate thread so that the UI continues to work
                var thread = new Thread(MigrateProductStats);
              thread.Start(corporation.Corporation.Id); // This enables me to pick the manufacturer that we are summarizing for
             }
        }

    }

 private void MigrateProductStats(object corporationIdObj)
    {
       // after thread completion I need to Enable my buttons.
        buttonProductStatsAndRetailerStats.Enabled = true;
        buttonSummariseProductStats.Enabled = true;

    }

You must use Control.Invoke see http://msdn.microsoft.com/en-us/library/system.windows.forms.control.invoke.aspx — Alessandro D'Andria, Sep 08 '13 at 18:13
@I4V I tried diffrent ways not able to find the solution . looked into http://bathinenivenkatesh.blogspot.co.uk/2011/07/wpf-build-more-responsive-ui.html — 62071072SP, Sep 08 '13 at 18:15
@62071072 Strange since the first hit answers your problem :) — I4V, Sep 08 '13 at 18:16

score 3 · Accepted Answer · answered Sep 08 '13 at 18:15

3

Try with:

private void MigrateProductStats(object corporationIdObj)
{
    Invoke(new Action(() =>
    {
       // after thread completion I need to Enable my buttons.
       buttonProductStatsAndRetailerStats.Enabled = true;
       buttonSummariseProductStats.Enabled = true;
    });
}

answered Sep 08 '13 at 18:15

Alessandro D'Andria

8,663
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Thanks It worked. If I need to run two threads on one button click do I need to use Invoke? – 62071072SP Sep 08 '13 at 18:26
You need invoke when changes a control from a thread tha not is the thread that created it. if you're not sure you can use `InvokeRequired` property that tell you if you need to use `Invoke`. see http://msdn.microsoft.com/en-us/library/system.windows.forms.control.invokerequired.aspx – Alessandro D'Andria Sep 08 '13 at 18:35
@AlessandroD'Andria: it's safe to use `Invoke` even when not required. – Ben Voigt Sep 08 '13 at 18:55
Yes, it's just to know when you must use `Invoke`. – Alessandro D'Andria Sep 08 '13 at 19:13

Ben Voigt · Answer 2 · 2013-09-08T18:30:09.430

0

Even better than Control.Invoke would be to use BackgroundWorker to handle threading for you. It generates progress and completion events back on the UI thread to make UI updates easy.

If you're using C# 5, you can also use async to start the background processing and await to cause the UI updates to occur when processing completes.

edited Sep 08 '13 at 18:30

answered Sep 08 '13 at 18:18

Ben Voigt

277,958
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Even better would be TPL (async/await) – I4V Sep 08 '13 at 18:20
@BenVoigt If you post a specific code, I can happily post an answer. – I4V Sep 08 '13 at 18:25
@BenVoigt No, `await` doesn't work like `WaitHandle.WaitOne` – I4V Sep 08 '13 at 18:29
Thanks, added it as another suggestion in my answer, with the note about requiring newer C#. – Ben Voigt Sep 08 '13 at 18:30

The calling thread cannot access this object because a different thread owns it" exception

2 Answers2