No, the Set & Reset calls must be sync'ed too Look at those two running threads using InterlockedBlah: calls = 1 Thread A calls Set Thread B calls Reset
Thread A : decr (calls is now 0) Thread B : comp (calls == 0) Thread B : evt.Reset Thread A : evt.Set Thread B : incr (calls is now 1) now we have the event in a signaled state, while calls != 0. Thats is a bug, the event must be signaled only when there a 0 calls. // Ryan On 7/20/07, Nassar, Anthony <[EMAIL PROTECTED]> wrote:
Ryan, couldn't you just use the InterlockedBlah methods to save yourself from having to lock? -----Original Message----- From: Discussion of advanced .NET topics. [mailto:[EMAIL PROTECTED] On Behalf Of Ryan Heath Sent: Friday, July 20, 2007 4:37 AM To: [email protected] Subject: Re: [ADVANCED-DOTNET] Question about the right way to use BackGroundWorker I have added a simple class CountedEvent to your code [1] Now you do not have to burn the cpu waiting for all jobs to finish. Its interesting to see that RunWorkerCompleted is called after(!) all jobs have finished... This is due to that BackgroundWorker is designed to work in an UI environment. When no real UI response is needed the BackgroundWorker would not be my first choice for this kind of work. I supports Gregs suggestion to use QueueUserWorkItem, and perhaps in combination with CountedEvent. HTH // Ryan [1] using System; using System.Collections.Generic; using System.Text; using System.ComponentModel; using System.Threading; using System.Collections; namespace BackgroundWorkerDemo { class CountedEvent { ManualResetEvent evt = new ManualResetEvent(true); int calls = 0; public void WaitOne() { evt.WaitOne(); } public void Set() { lock( evt) { calls--; if ( calls == 0) { evt.Set(); } } } public void Reset() { lock( evt) { if ( calls == 0) { evt.Reset(); } calls++; } } } class Program { static void Main(string[] args) { DateTime start_time = DateTime.Now; Console.WriteLine("Program starting"); //RunSyncVersion(); RunAsyncVersion(); DateTime end_time = DateTime.Now; TimeSpan ts = end_time - start_time; Console.WriteLine("Program completed. Duration={0} seconds.", ts.Seconds); Console.Read(); } //Synchronous version static void RunSyncVersion() { for (int i = 0; i <= 10; i++) { LongRunningOperation(i); } } //This version uses the async version static void RunAsyncVersion() { CountedEvent jobFinished = new CountedEvent(); ArrayList lstBGWs = new ArrayList(); for (int i = 0; i <= 10; i++) { BackgroundWorker worker = new BackgroundWorker(); jobFinished.Reset(); worker.DoWork += new DoWorkEventHandler(worker_DoWork); worker.RunWorkerCompleted += delegate(object sender, RunWorkerCompletedEventArgs e) { jobFinished.Set(); Console.WriteLine("Set called"); }; lstBGWs.Add(worker); worker.RunWorkerAsync(i); } jobFinished.WaitOne(); Console.WriteLine("exit"); } static void worker_DoWork(object sender, DoWorkEventArgs e) { BackgroundWorker worker = sender as BackgroundWorker; LongRunningOperation(Convert.ToInt32(e.Argument)); } //Long running operation private static void LongRunningOperation(int operation_number) { Console.WriteLine("Operation# {0} starting on Thread {1}", operation_number, Thread.CurrentThread.ManagedThreadId); for (int i=0; i < 1000000000; i++) { } Console.WriteLine("Finished operation# {0} on Thread {1}", operation_number, Thread.CurrentThread.ManagedThreadId); } } } =================================== This list is hosted by DevelopMentor(r) http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com =================================== This list is hosted by DevelopMentor(r) http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com
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