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POWhy don't my event handlers fire when I'm reading from the standard output of another process
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2012-05-22T22:25:18.813
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2012-05-23T15:46:17.427
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2012-05-23T02:25:14.220
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I have a very simple C# project that has a UI process and a worker process. The worker code needs to be a process (rather than a thread) because it can be run by either the UI or by the Windows Task Scheduler. In the UI code, I set the <code>ProcessStartInfo.RedirectStandardOutput</code> to <code>true</code> and I register the event handlers. Then, I start the process (with <code>Process.Start()</code> and call <code>Process.BeginOutputReadline()</code>. Yet, the method that I have designated as the OutputDataReceived event handler never fires. When I run the worker process without redirecting it's standard output, I see the expected output on the console. When I turn on output redirection, I don't see anything on the console (as expected), but the event handlers don't fire either. Is there something else that I need to to read asynchronously from another process' standard output stream? EDIT: I've managed to replicate the problem with two simple console processes. First the parent: <pre><code>using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading; using System.Diagnostics; namespace OutputRedirectionEventHandlerTest { class ParentProgram { static void Main(string[] args) { ProcessStartInfo processInfo = new ProcessStartInfo() { FileName = "OutputRedirectionWorker.exe", RedirectStandardOutput = true, UseShellExecute = false }; Process subProcess = new Process() { StartInfo = processInfo }; subProcess.OutputDataReceived += new DataReceivedEventHandler(OutputHandler); subProcess.Start(); subProcess.BeginOutputReadLine(); } static void OutputHandler(object SendingProcess, DataReceivedEventArgs args) { Console.Out.WriteLine("Received from subprocess: " + args.Data); } } } </code></pre> And then, the child: <pre><code>using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Diagnostics; using System.Threading; namespace OutputRedirectionWorker { class ChildProgram { static void Main(string[] args) { Console.Out.WriteLine("Output1"); Console.Out.WriteLine("Output2"); Console.Out.WriteLine("Output3"); Thread.Sleep(10000); } } } </code></pre> No output ever gets printed by the parent.
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Why don't my event handlers fire when I'm reading from the standard output of another process
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