C# 秒表显示不正确的时间

Question

我看到其他用户帖子显示秒表测量“Thread.Sleep(5000)”花费的时间约为 5000 毫秒。

但我的程序产生以下结果

for (int i = 0; i < 20; ++i)
{
    Stopwatch sw = Stopwatch.StartNew();
    DateTime start = DateTime.Now;
    Thread.Sleep(5000);
    sw.Stop();
    Console.Out.WriteLine(
        "StopWatch Diff:" + 
        sw.ElapsedMilliseconds.ToString()); 
    Console.Out.WriteLine(
        "DateTime Diff:" + 
        DateTime.Now.Subtract(start).TotalMilliseconds.ToString());
}

---

StopWatch Diff:1684
DateTime Diff:5262.592
StopWatch Diff:1625
DateTime Diff:4997.12
StopWatch Diff:1604
DateTime Diff:4997.12
StopWatch Diff:1601
DateTime Diff:4997.12
StopWatch Diff:1690
DateTime Diff:4997.12
StopWatch Diff:1603

只有我在观察这种行为吗？为什么秒表实际已经过去了 5 秒，却测量到了 1.6 秒。是线程实际运行的时间吗？

Answer 1

Stopwatch 类是 不可靠。

这对于没有恒定时钟速度的处理器来说是不可靠的（大多数处理器可以降低时钟速度以节省能源）。 此处对此进行了详细解释。