gistfile1.cs

void Main()
{
    using(var l = new ReaderWriterLockSlim())
	{	
		var tasks = Enumerable.Range(0,2).Select (i => 
			Task.Run(() =>
			{
				l.EnterUpgradeableReadLock();
				try
				{
					Console.WriteLine("Task {0} has entered the lock.", i);
					while (true) Thread.Sleep(int.MaxValue);
				}
				finally
				{
					l.ExitUpgradeableReadLock();
				}
			})).ToArray();
		
		Task.WaitAll(tasks);
	}
}