Singleton

public sealed class Singleton<T> where T:new()
    ...{
        private static T instance = new T();
        private static object lockHelper = new object();
        private Singleton() ...{ }
        public static T GetInstance()
        ...{
            if (instance == null)
            ...{
                lock (lockHelper)
                ...{
                    if (instance == null)
                    ...{
                        instance = new T();
                    }
                }
            }
            return instance;
        }
    }