"Ashish" <ash***@discussions.microsoft.com.> wrote in message
news:A084829C-5C40-452B-8247-5A1A2F792C4E@microsoft.com...
| We have a requirement to implement multithreaded processing for a
function.
| ThreadPool is used to implement multithreading in order to avoid the over
| head of creating and destroying Threads dynamically.
| A function will Queues the method calls to the default ThreadPool. If the
| number of method calls is more than the ThreadPool size, it will get
queued
| for getting a slot in the ThreadPool.
| Our requirement is to implement a Time-out in the waitQueue of the
| ThreadPool. If a request is queued in the ThreadPool for a pre-defined
amount
| of time, it should get Timeout, notify the user and that particular
request
| should not go inside the ThreadPool again. In short, if a thread is not
| available, the thread manager should wait for one to become available. If
| none become available within a time period, then the process would fail
out,
| leaving the existing threads to complete
|
| For implementing this we used ThreadPool.RegisterWaitForSingleObject
method.
| The problem here is that even though we can specify a Time out in
| millisecond, the Timeout delegate also will get queued in the ThreadPool
and
| the Original request will get executed before the Timeout delegate. We
have
| to give some kind of priority to the Timeout delegate, so that if a
request
| gets Timeout, the same request will not get processed.
|
| Sample Code which simulates the situation:
|
| private void btnStart_Click(object sender, EventArgs e)
|   {
| AutoResetEvent arEvent = new AutoResetEvent(false);
| ThreadPool.SetMaxThreads(2, 2);
|      for (int i = 0; i < 10; i++)
|      {
|          ThreadPool.RegisterWaitForSingleObject(arEvent, new
| WaitOrTimerCallback(Print), "Object"+ i , 2000, true);
|     arEvent.Set();
|     //Time out is set as 2 seconds and ThreadPool size is 2
|      }
|   }
|
|
|
| Public void Print(object state, bool timedOut)
|   {
|     TimeSpan waitTime = DateTime.Now.Subtract(tInfo.TaskQueuedTime);
|     if (waitTime.TotalMilliseconds < TIMEOUT)
|        {
|           MessageBox.Show("Executing " + state.ToString());
|      Thread.Sleep(3000);
|      //Thread is taking more than 3 seconds to complete the task
|        }
|        else
|        {
|            Console.out.WriteLine("Time Out " + state.ToString());
|        }
|    }
|
| Based on our requrement, the ThreadPool should show MessageBox only for
| first two items in the queue and it should write the Time Out in console
for
| all the remaining eight items in the queue. But its actual behaviour is
that,
| Its showing MessageBox for all the ten items in the Queue and shows Time
Out
| for the last eight items. The Time Out for last eight items are invoked
after
| showing all the ten MessageBoxes.
|
| The reason why its happened is because, even the TimeOut delegate is also
| getting queued in the ThreadPool.
|
| Can anyone please suggest a solution to resolve this issue.
| Thanking you in advance
|
|
|

> I wrote up a detailed blog entry on this a few months back that can be found
> at: http://www.coversant.net/dotnetnuke/Default.aspx?tabid=88&EntryID=8

|
| Brian
|
| Chris Mullins wrote:
| > I wrote up a detailed blog entry on this a few months back that can be
found
| > at: http://www.coversant.net/dotnetnuke/Default.aspx?tabid=88&EntryID=8
|