static void Main(string[] args)
{
// 仅支持单线程
var instance = Singleton.GetInstance();
// 多线程，有额外的开销
var instance1 = Singleton1.GetInstance();
// Double check
var instance2 = Singleton2.GetInstance();
}
public static Singleton2 GetInstance()
{
if (_unqiueInstance == null)
{
lock (locker)
{
if (_unqiueInstance == null)
{
_unqiueInstance = new Singleton2();
}
}
}
return(_unqiueInstance);
}