MemoryCache helper class async locking test

gistfile1.txt

void Main()
{
	var key1Task = new Task<string>(() => ExampleCache.GetItem("key1"));
	var key2Task = new Task<string>(() => ExampleCache.GetItem("key2"));
	key1Task.Start();
	key2Task.Start();
	Task.WaitAll(key1Task, key2Task);
	key1Task.Result.Dump();
	key2Task.Result.Dump();
}

// Define other methods and classes here
public static class ExampleCache
{
	private static MemoryCache _cache = new MemoryCache("ExampleCache");

	public static string GetItem(string key)
	{
		return AddOrGetExisting(key, () => InitItem(key));
	}

	private static T AddOrGetExisting<T>(string key, Func<T> valueFactory)
	{
		var newValue = new Lazy<T>(valueFactory);
		var oldValue = _cache.AddOrGetExisting(key, newValue, new CacheItemPolicy()) as Lazy<T>;
		try
		{
			return (oldValue ?? newValue).Value;
		}
		catch
		{
			// Handle cached lazy exception by evicting from cache. Thanks to Denis Borovnev for pointing this out!
			_cache.Remove(key);
			throw;
		}
	}

	private static string InitItem(string key)
	{
		Console.WriteLine($"Initializing {key}");
		Thread.Sleep(1000);
		Console.WriteLine($"Finished {key}");
		return key.ToUpper();
	}
}