Thread pool problem with System.Diagnostic.Process

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threads

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I am using ThreadPool to make multiple calls to a method called RunScripts. Number of threads are maintained by a count of number of sql scriptfile to run. If there are 4 sqlscripts to run then I make call to ThreadPool.QueueUserWorkItem 4 times and son on. In the RunScripts method, I am using System.Diagnostic.Process to run the sql scripts as shown is the code. The Process has two event handlers namely OutPutDataReceived and ErrorDataRecieved. In both of the events, I am simply printing the message in console. I have set the ThreadPool.SetMinThreads=4 and ThreadPool.SetMaxThreads=10.

In the code, I have called executorProcess.CancelOutputRead() and executorProcess.CancelErrorRead() as soon as my process finish the work. If I am not wrong the program execution reach these lines only after the two events are called if there are any standard output/error . My scripts finish execution within 3 or 4 seconds. My problem here is OutputDataReceived and ErrorDataReceived events are not called for every threads. Asynchronous reads are being cancelled before the two events are invoked.However, if I increase the MinThreads and MasThreads then the two events are called before the debug point reach CancelOutputRead() and CancelErrorRead().

when I removed the executorProcess.CancelOutputRead() and executorProcess.CancelErrorRead() from the code then every standard ouput and error are being printed. I am not sure why it is not working when there are less number of threads.

Private void RunScripts()
{

      // Start SQLCMD process.
                ProcessStartInfo psi = new ProcessStartInfo();
                psi.FileName = "SQLCMD.EXE";
                string args = "-S " + this.Server;
                if (string.IsNullOrEmpty(this.UserName)) args += " -E";
                else args += " -U " + this.UserName;
                if (!string.IsNullOrEmpty(scriptFile.Database))
                    args += " -d " + scriptFile.Database;
                if (string.IsNullOrEmpty(this.Password))
                    args += " -i " + scriptFilePath;
                else
                    args += " -P " + this.Password + " -i " + scriptFilePath;
                psi.Arguments = args;
                psi.RedirectStandardOutput = true;
                psi.RedirectStandardError = true;
                psi.UseShellExecute = false;

                using (Process executorProcess = Process.Start(psi))
                {
                    executorProcess.EnableRaisingEvents = true;
                    executorProcess.OutputDataReceived +=
                        new DataReceivedEventHandler(
                            this.executorProcess_DataReceived);
                    executorProcess.ErrorDataReceived +=
                        new DataReceivedEventHandler(executorProcess_ErrorDataReceived);
        
                    executorProcess.BeginOutputReadLine();
                    executorProcess.BeginErrorReadLine();
                    bool exited = false;
                    while (!exited)
                    {
                        exited = executorProcess.WaitForExit(60000);
                        if (!exited && this.StopSignal)
                        {
                            try { executorProcess.Kill(); }
                            catch { }
                        }
                    }
                    try
                    {
                        executorProcess.CancelOutputRead();
                        executorProcess.CancelErrorRead();
                    }
                    catch { }
}


        void executorProcess_ErrorDataReceived(object sender, DataReceivedEventArgs e)
        {
          Console.WriteLine(e.Data);
        }

       private void executorProcess_DataReceived(object sender,
            DataReceivedEventArgs e)
        {
            Console.WriteLine(e.Data);
        }