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POBeginInvoke is blocking the UI whereas Invoke is not.!
 

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  1. POBeginInvoke is blocking the UI whereas Invoke is not.!
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    <p>I am confused with scenario which I have encountered with cross thread access. Here is what I am trying to do:</p> <p>Main UI thread - menu item click I create a background worker and run it asynchronously</p> <pre><code>private void actionSubMenuItem_Click(object sender, EventArgs e) { ToolStripMenuItem itemSelected = (ToolStripMenuItem)sender; ExecuteTheActionSelected(itemSelected.Text); } </code></pre> <p>The method <code>ExecuteTheActionSelected</code> is as follows:</p> <pre><code>private void ExecuteTheActionSelected(string actionSelected) { BackgroundWorker localBackgroundWorker = new BackgroundWorker(); localBackgroundWorker.DoWork += new DoWorkEventHandler(localBackgroundWorker_DoWork); localBackgroundWorker.RunWorkerAsync(SynchronizationContext.Current); } </code></pre> <p>The <code>localBackgroundWorker_DoWork</code> has:</p> <pre><code> ActionExecutionHelper actionExecutioner = new ActionExecutionHelper() actionExecutioner.Execute(); </code></pre> <p>The <code>Execute</code> method in that class that has method invoker which infact invokes the event handler in UI thread:</p> <pre><code> public void Execute() { // ---- CODE ----- new MethodInvoker(ReadStdOut).BeginInvoke(null, null); } protected virtual void ReadStdOut() { string str; while ((str = executionProcess.StandardOutput.ReadLine()) != null) { object sender = new object(); DataReceivedEventArgs e = new DataReceivedEventArgs(str); outputDataReceived.Invoke(sender, e); //This delegate invokes UI event handler } } </code></pre> <p>The UI event handler is as follows:</p> <pre><code>private void executionProcess_OutputDataReceived(object sender, DataReceivedEventArgs e) { if (_dwExecuteAction != null) { _dwExecuteAction.ShowDataInExecutionWindow(e.Text); } } </code></pre> <p><strong>Now here comes the cross thread issue</strong>:</p> <pre><code>public void ShowDataInExecutionWindow(string message) { if (rchtxtExecutionResults.InvokeRequired) { rchtxtExecutionResults.Invoke(new ShowDataExecutionDelegate(ShowDataInExecutionWindow), message); } else { this.rchtxtExecutionResults.AppendText(message + Environment.NewLine); } } </code></pre> <p>Here <strong>Invoke doesn't block the UI where as BeginInvoke blocks</strong>. Please help me understand this scenario as i m confused a lot.</p>
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    1. USNagaraj Tantri
    1. USNagaraj Tantri
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      1. POBeginInvoke is blocking the UI whereas Invoke is not.!
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      1. POBeginInvoke is blocking the UI whereas Invoke is not.!
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      1. POBeginInvoke is blocking the UI whereas Invoke is not.!
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    1. COI'm afraid I don't know the answer, but the approach I would take to finding it out would be looking at how the multiple levels of invocation and background workers interact with each other, and where everything actually gets executed so that you understand how everything fits together.
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      1. USMatthew Walton
 

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