在我的电脑上,秒表返回的值太低了。例如,当我指定 200 毫秒时Thread.Sleep(1000)
。该程序应该等待 1 秒。我也进行了测试ManualResetEvent.WaitOne(1000)
并得到了相同的结果。框架 2.0 和 3.0 都给出了这种奇怪的行为。我正在运行带有 .NET Framework 3.5 SP1 的 Windows XP SP3。
这是我的测试结果(下面的代码):
1000 ms for DateTime.Now.Ticks
0201 ms for Stopwatch.ElapsedTicks
0142 ms for Stopwatch.ElapsedMilliseconds
0139 ms for Stopwatch.ElapsedTicks after Reset
0264 ms for Stopwatch.ElapsedTicks setting ThreadAffinity
0151 ms for Stopwatch.ElapsedTicks setting ProcessorAffinity (and more)
0371 ms for Stopwatch.ElapsedTicks with Syncronized object
Done!
// Program.cs 文件
class Program
{
static void Main(string[] args)
{
StopWatchTest.Go();
Console.WriteLine("Done!");
Console.ReadLine();
}
}
// StopWatchTest.cs 类
internal static class StopWatchTest
{
public const int SleepTime = 1000;
public static void Go()
{
#region Test #0 with DateTime.Now.Ticks
long startTick = DateTime.Now.Ticks;
Thread.Sleep(SleepTime);
long stopTick = DateTime.Now.Ticks;
long elapsedDt = (stopTick - startTick) * 100;
Display((int)(elapsedDt / 1000 / 1000), "DateTime.Now.Ticks");
#endregion Test #0 with DateTime.Now.Ticks
Stopwatch watch = Stopwatch.StartNew();
long frequency = Stopwatch.Frequency;
double nanosecPerTick = (1000.0 * 1000.0 * 1000.0) / frequency;
#region Test #1 with Stopwatch.ElapsedTicks
startTick = watch.ElapsedTicks;
Thread.Sleep(SleepTime);
stopTick = watch.ElapsedTicks;
double elapsedSw = (stopTick - startTick) * nanosecPerTick;
Display((int)(elapsedSw / 1000 / 1000), "Stopwatch.ElapsedTicks");
#endregion Test #1 with Stopwatch.ElapsedTicks
#region Test #2 with Stopwatch.ElapsedMilliseconds
startTick = watch.ElapsedMilliseconds;
Thread.Sleep(SleepTime);
stopTick = watch.ElapsedMilliseconds;
Display((int)(stopTick - startTick), "Stopwatch.ElapsedMilliseconds");
#endregion Test #2 with Stopwatch.ElapsedMilliseconds
#region Test #3 with Stopwatch.ElapsedTicks after Reset
watch.Stop();
watch.Reset();
watch.Start();
startTick = watch.ElapsedTicks;
Thread.Sleep(SleepTime);
stopTick = watch.ElapsedTicks;
elapsedSw = (stopTick - startTick) * nanosecPerTick;
Display((int)(elapsedSw / 1000 / 1000), "Stopwatch.ElapsedTicks after Reset");
#endregion Test #3 with Stopwatch.ElapsedTicks after Reset
#region Test #4 with Stopwatch.ElapsedTicks and ThreadAffinity
Thread.BeginThreadAffinity();
startTick = watch.ElapsedTicks;
Thread.Sleep(SleepTime);
stopTick = watch.ElapsedTicks;
elapsedSw = (stopTick - startTick) * nanosecPerTick;
Display((int)(elapsedSw / 1000 / 1000), "Stopwatch.ElapsedTicks setting ThreadAffinity");
Thread.EndThreadAffinity();
#endregion Test #4 with Stopwatch.ElapsedTicks and ThreadAffinity
#region Test #5 with Stopwatch.ElapsedTicks and ProcessorAffinity (and more)
const int affinity = 0x0001;
Process proc = Process.GetCurrentProcess();
proc.ProcessorAffinity = new IntPtr(affinity);
proc.PriorityClass = ProcessPriorityClass.High;
ProcessThreadCollection ptc = proc.Threads;
foreach (ProcessThread pt in ptc)
{
pt.IdealProcessor = 0;
pt.ProcessorAffinity = new IntPtr(affinity);
}
Thread.CurrentThread.Priority = ThreadPriority.Highest;
startTick = watch.ElapsedTicks;
Thread.Sleep(SleepTime);
stopTick = watch.ElapsedTicks;
elapsedSw = (stopTick - startTick) * nanosecPerTick;
Display((int)(elapsedSw / 1000 / 1000), "Stopwatch.ElapsedTicks setting ProcessorAffinity (and more)");
#endregion Test #5 with ProcessorAffinity and more
#region Test #6 with Syncronized object
elapsedSw = new SyncTimer().Go();
Display((int)(elapsedSw / 1000 / 1000), "Stopwatch.ElapsedTicks with Syncronized object");
#endregion Test #6 with Syncronized object
}
private static void Display(int milliseconds, string testName)
{
Console.WriteLine("{0:0000} ms for {1}", milliseconds, testName);
}
}
[Synchronization]
internal class SyncTimer : ContextBoundObject
{
[MethodImpl(MethodImplOptions.Synchronized)]
public double Go()
{
Stopwatch.StartNew();
long frequency = Stopwatch.Frequency;
double nanosecPerTick = (1000.0 * 1000.0 * 1000.0) / frequency;
long startTick = Stopwatch.GetTimestamp();
Thread.Sleep(StopWatchTest.SleepTime);
long stopTick = Stopwatch.GetTimestamp();
return (stopTick - startTick) * nanosecPerTick;
}
}