Example of waiting for several threads to complete

ManualResetThreads.cs

public class Program
{
	private static Thread one;
	private static Thread two;
	private static Thread three;

	private static HybridDictionary events;

	static void Main(string[] args)
	{
		events = new HybridDictionary();

		one = new Thread(Action);
		two = new Thread(Action);
		three = new Thread(Action);

		one.Start(1);
		two.Start(2);
		three.Start(3);

		var cts = new CancellationTokenSource();
		var ct = cts.Token;

		Task.Factory.StartNew(() =>
		{
			bool completed = false;
			while (!ct.IsCancellationRequested && !completed)
			{
				completed = 
					WaitHandle.WaitAll(
						events.Values.Cast<ManualResetEvent>().ToArray(),
						TimeSpan.FromSeconds(1));
			}

			if (completed)
				Console.WriteLine("Changed!");
		});
		
		Console.ReadKey();
	}

	public static void Action(object id)
	{
		var ev = new ManualResetEvent(false);
		events[id] = ev;

		Thread.Sleep(2000 * (int)id);

		ev.Set();
	}
}