Timers

Timers are lightweight objects that enable you to specify a delegate to be called at a specified time. A thread in the thread pool performs the wait operation.

Using the System.Threading.Timer class is straightforward. You create a Timer, passing a TimerCallback delegate to the callback method, an object representing state that will be passed to the callback, an initial raise time, and a time representing the period between callback invocations. To cancel a pending timer, call the Timer.Dispose function.

Note Note

There are two other timer classes. The System.Windows.Forms.Timer class is a control that works with visual designers and is meant to be used in user interface contexts; it raises events on the user interface thread. The System.Timers.Timer class derives from Component, so it can be used with visual designers; it also raises events, but it raises them on a ThreadPool thread. The System.Threading.Timer class makes callbacks on a ThreadPool thread and does not use the event model at all. It also provides a state object to the callback method, which the other timers do not. It is extremely lightweight.

The following code example starts a timer that starts after one second (1000 milliseconds) and ticks every second until you press the Enter key. The variable containing the reference to the timer is a class-level field, to ensure that the timer is not subject to garbage collection while it is still running. For more information on aggressive garbage collection, see KeepAlive.

using System;
using System.Threading;

public class Example
{
    private static Timer ticker;

    public static void TimerMethod(object state)
    {
        Console.Write(".");
    }

    public static void Main()
    {
        ticker = new Timer(TimerMethod, null, 1000, 1000);

        Console.WriteLine("Press the Enter key to end the program.");
        Console.ReadLine();
    }
}
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