一尘不染

C#静态构造函数线程安全吗?

c#

换句话说,此Singleton实现线程是否安全:

public class Singleton
{
    private static Singleton instance;

    private Singleton() { }

    static Singleton()
    {
        instance = new Singleton();
    }

    public static Singleton Instance
    {
        get { return instance; }
    }
}

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2020-05-19

共1个答案

一尘不染

在创建类的任何实例或访问任何静态成员之前,保证静态构造函数在每个应用程序域仅运行一次。https://docs.microsoft.com/zh-
cn/dotnet/csharp/programming-guide/classes-and-structs/static-
constructors

所示的实现对于初始构造是线程安全的,也就是说,构造Singleton对象不需要进行锁定或空测试。但是,这并不意味着实例的任何使用都将被同步。有很多种方法可以做到这一点。我在下面显示了一个。

public class Singleton
{
    private static Singleton instance;
    // Added a static mutex for synchronising use of instance.
    private static System.Threading.Mutex mutex;
    private Singleton() { }
    static Singleton()
    {
        instance = new Singleton();
        mutex = new System.Threading.Mutex();
    }

    public static Singleton Acquire()
    {
        mutex.WaitOne();
        return instance;
    }

    // Each call to Acquire() requires a call to Release()
    public static void Release()
    {
        mutex.ReleaseMutex();
    }
}
2020-05-19