c# - 我有一个 Singleton 类，但返回两个。我需要两个 lok 对象吗？

Question

public class Manager {
    private static Manager _one;
    private static Manager _two;
    private static object Obj_Lock_one = new object();
    private static object Obj_Lock_two = new object();//Do I need Obj_Lock_two here ?

    public static Manager GetOne ()
    {
            if (_one == null)
            {
                lock (Obj_Lock_one)
                {
                    if (_one == null)
                    {
                        _one = new Manager();
                    }
                }
            }

            return _one;
    }
    public static Manager GetTwo ()
    {
            if (_two == null)
            {
                lock (Obj_Lock_two) //Do I need Obj_Lock_two here ?
                {
                    if (_two == null)
                    {
                        _two = new Manager();
                    }
                }
            }

            return _two;
    }
}

我需要第二个对象来锁定吗？在 GetTwo 方法中，我应该使用“lock(Obj_Lock_one)”还是“lock(Obj_Lock_two)”

如果我只用一个obj来加锁，我想可能只会阻塞一个thred...

那么正确的方法是什么？

Answer 1

Do I need a second obj to lock?

如果两个线程同时调用 GetOne()，在这里使用第二个锁对象将稍微提高性能。和 GetTwo()第一次同时。换句话说:您可能无法衡量差异。

SO what is the correct way?

不要重新发明轮子。废弃你的代码并使用 Lazy initialization with Lazy<T> 相反，它是线程安全的并自动处理所有这些线程同步问题:

public sealed class Manager
{
    private static readonly Lazy<Manager> lazyOne = new Lazy<Manager>(() => new Manager());
    private static readonly Lazy<Manager> lazyTwo = new Lazy<Manager>(() => new Manager());

    public static Manager GetOne() { return lazyOne.Value; }
    public static Manager GetTwo() { return lazyTwo.Value; }
}