为什么用 Thread.Sleep 检查秒表似乎不准确？

Question

我尝试实现 .NET Stopwatch 是为了好玩，但我得到了一些意想不到的结果。

我完全期望这个程序的执行时间大约为 100 毫秒。

是 Stopwatch class 不准确还是这里发生了什么？

代码：

namespace Timer
{
    class Program
    {
        Stopwatch s = new Stopwatch();

        static void Main(string[] args)
        {
            s.Start();
            for (int i = 0; i < 100; i++)
            {
                Thread.Sleep(1);
            }
            s.Stop();

            Console.WriteLine("Elapsed Time " + s.ElapsedMilliseconds + " ms");

            Console.ReadKey();
        }
    }
}

结果是190 ms

Answer 1

因为Thread.Sleep(n)意味着：至少 n 毫秒。

前段时间I wrote an answer (on another topic though), which contained an external reference:

Thread.Sleep(n) means block the current thread for at least the number of timeslices (or thread quantums) that can occur within n milliseconds. The length of a timeslice is different on different versions/types of Windows and different processors and generally ranges from 15 to 30 milliseconds. This means the thread is almost guaranteed to block for more than n milliseconds. The likelihood that your thread will re-awaken exactly after n milliseconds is about as impossible as impossible can be. So, Thread.Sleep is pointless for timing.

根据MSDN：

The system clock ticks at a specific rate called the clock resolution. The actual timeout might not be exactly the specified timeout, because the specified timeout will be adjusted to coincide with clock ticks.

Answer 2

因为你不是实时的OS，你的程序可能会被其他东西打断，使用 Sleep 会增加这种情况发生的几率，即使你线程等待的毫秒数也会至少 n 毫秒。尝试使用普通的 Thread.Sleep(100)，您可能会找到更接近的东西。

为什么用 Thread.Sleep 检查秒表似乎不准确？

Why Stopwatch seems to be inaccurate if checked with Thread.Sleep?

c#

stopwatch