lock() 是否保证按请求的顺序获得?-C#/.NET问题

Does lock() guarantee acquired in order requested?(lock() 是否保证按请求的顺序获得?)

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问题描述

当多个线程请求同一个对象上的锁时，CLR 是否保证将按照它们被请求的顺序获取锁?

When multiple threads request a lock on the same object, does the CLR guarantee that the locks will be acquired in the order they were requested?

我写了一个测试看看这是不是真的，它似乎表明是的，但我不确定这是否是确定的.

I wrote up a test to see if this was true, and it seems to indicate yes, but I'm not sure if this is definitive.

class LockSequence
{
    private static readonly object _lock = new object();

    private static DateTime _dueTime;

    public static void Test()
    {
        var states = new List<State>();

        _dueTime = DateTime.Now.AddSeconds(5);
        
        for (int i = 0; i < 10; i++)
        {
            var state = new State {Index = i};
            ThreadPool.QueueUserWorkItem(Go, state);
            states.Add(state);
            Thread.Sleep(100);
        }
        
        states.ForEach(s => s.Sync.WaitOne());
        states.ForEach(s => s.Sync.Close());
    }

    private static void Go(object state)
    {
        var s = (State) state;

        Console.WriteLine("Go entered: " + s.Index);

        lock (_lock)
        {
            Console.WriteLine("{0,2} got lock", s.Index);
            if (_dueTime > DateTime.Now)
            {
                var time = _dueTime - DateTime.Now;
                Console.WriteLine("{0,2} sleeping for {1} ticks", s.Index, time.Ticks);
                Thread.Sleep(time);
            }
            Console.WriteLine("{0,2} exiting lock", s.Index);
        }

        s.Sync.Set();
    }

    private class State
    {
        public int Index;
        public readonly ManualResetEvent Sync = new ManualResetEvent(false);
    }
}

打印:

进入:0

0 被锁定

0 睡眠 49979998 滴答

0 sleeping for 49979998 ticks

进入:1

进入:2

进入:3

进入:4

进入:5

进入:6

进入:7