Multithreaded Timers

System.Threading.Timer - Simplest multithreaded timer. Contains two methods and one constructor.

Example: A timer calls the DataWrite method, which writes “multithread executed…” after five seconds have elapsed, and then every second after that until the user presses Enter:

using System;
using System.Threading;
class Program
{
  static void Main()
  {
    // First interval = 5000ms; subsequent intervals = 1000ms
    Timer timer = new Timer (DataWrite, "multithread executed...", 5000, 1000);
    Console.ReadLine();
    timer.Dispose(); // This both stops the timer and cleans up.
  }

  static void DataWrite (object data)
  {
    // This runs on a pooled thread
    Console.WriteLine (data); // Writes "multithread executed..."
  }
}

Note : Will post a separate section for disposing multithreaded timers.

Change - This method can be called when you would like change the timer interval.

Timeout.Infinite - If you want to fire just once. Specify this in the last argument of the constructor.

System.Timers - Another timer class provided by .NET Framework. It wraps the System.Threading.Timer.

Features:

• IComponent - Allowing it to be sited in the Visual Studio’s Designer’s component tray
• Interval property instead of a Change method
• Elapsed event instead of a callback delegate
• Enabled property to start and stop the timer (default value = false)
• Start & Stop methods in case if you get confused by Enabled property (above point)
• AutoReset - for indicating a recurring event (default value = true)
• SynchronizingObject property with Invoke and BeginInvoke methods for safely calling methods on WPF elements and Windows Forms controls

Example representing all the above features:

using System;
using System.Timers; // Timers namespace rather than Threading
class SystemTimer
{
  static void Main()
  {
    Timer timer = new Timer(); // Doesn't require any args
    timer.Interval = 500;
    timer.Elapsed += timer_Elapsed; // Uses an event instead of a delegate
    timer.Start(); // Start the timer
    Console.ReadLine();
    timer.Stop(); // Stop the timer
    Console.ReadLine();
    timer.Start(); // Restart the timer
    Console.ReadLine();
    timer.Dispose(); // Permanently stop the timer
 }

 static void timer_Elapsed(object sender, EventArgs e)
 {
   Console.WriteLine ("Tick");
 }
}

Multithreaded timers - use the thread pool to allow a few threads to serve many timers. It means that callback method or Elapsed event may trigger on a different thread each time it is called.

Elapsed - this event always fires on time—regardless of whether the previous Elapsed event finished executing. Because of this, callbacks or event handlers must be thread-safe. The accuracy of multithreaded timers depends on the OS, and is typically in the 10–20 ms.

interop - when ever you need greater accuracy use this and call the Windows multimedia timer. This has accuracy down to 1 ms and it is defined in winmm.dll.

timeBeginPeriod - Call this first to inform OS that you need high timing accuracy

timeSetEvent - call this after timeBeginPeriod to start a multimedia timer.

timeKillEvent - call this when you are done, this stops the timer

timeEndPeriod - Call this to inform the OS that you no longer need high timing accuracy.

You can find complete examples on the Internet that use the multimedia timer by searching for the keywords dllimport winmm.dll timesetevent.