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copied!<p>I see a couple of problems with the code.</p> <ul> <li>The check of <code>StopRequested</code> is not thread-safe.</li> <li>The check of <code>ExecutingTaskCount</code> is not thread-safe.</li> <li>Since <code>_finishedTaskAutoResetEvent</code> is an <code>AutoResetEvent</code> signals can get lost because that <code>WaitHandle</code> does not maintain a count. Maybe that is what you want, but it could result in some strange spinning of the nested <code>while</code> loops.</li> </ul> <p>Here is how I would refactor your code. It uses the <code>CountdownEvent</code> class which is available in .NET 4.0.</p> <pre><code>public class TaskScheduler : ServiceBase { private m_Stop as ManualResetEvent = new ManualResetEvent(false); protected override void OnStart(string[] args) { var thread = new Thread(DoSpawnTaskExecutionThreads); thread.Name = "Spawning Thread"; thread.IsBackground = false; thread.Start(); } protected override OnStop() { m_Stop.Set(); } public DoSpawnTaskExecutionThreads() { // The semaphore will control how many concurrent tasks can run. var pool = new Semaphore(MaxPooledThreads, MaxPooledThreads); // The countdown event will be used to wait for any pending tasks. // Initialize the count to 1 so that we treat this thread as if it // were a work item. This is necessary to avoid a subtle race // with a real work item that completes quickly. var tasks = new CountdownEvent(1); // This array will be used to control the spinning of the loop. var all = new WaitHandle[] { pool, m_Stop }; while (WaitHandle.WaitAny(all) == 0) { // Indicate that there is another task. tasks.AddCount(); // Queue the task. Thread.QueueUserWorkItem( (state) => { try { var task = (Task)state; task.Execute(); } finally { pool.Release(); // Allow another task to be queued. tasks.Signal(); // Indicate that this task is complete. } }, new Task()); } // Indicate that the main thread is complete. tasks.Signal(); // Wait for all pending tasks. tasks.Wait(); } } </code></pre>

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