C#使用Stopwatch精确测量运行时间

一般测量时间间隔使用的是DateTime.Now实例的DateTime.Ticks当前属性,想要精确测量一个操作的运行时间就只能使用Stopwatch类计时了。
Stopwatch计时精度取决于硬件,如果安装的硬件和操作系统支持高分辨率性能计数器, 则Stopwatch类将使用该计数器来测量运行时间。,否则,Stopwatch类将使用系统计时器来测量运行时间
测量耗时操作的运行时间:

            Stopwatch stopWatch = new Stopwatch();
            stopWatch.Start();
            Thread.Sleep(5000); // 耗时操作
            stopWatch.Stop();
            

            // 将经过的时间作为TimeSpan值
            TimeSpan ts = stopWatch.Elapsed;
            // 格式和显示时间值
            string elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:000}-{4:000}", ts.Hours, ts.Minutes, ts.Seconds, ts.Milliseconds, (ts.Ticks * 100 / 1000)%1000);
            Console.WriteLine("RunTime " + elapsedTime);

            // 将经过的时间作为毫秒数
            long mSeconds = stopWatch.ElapsedMilliseconds;
            Console.WriteLine("RunTime(ms) " + mSeconds);

            // 获取经过时间的计时器刻度
            // 也可在耗时操作前后使用Stopwatch.GetTimestamp()各获取1个Ticks值,然后相减得到耗时操作花费的计时器刻度
            // 计时器采用的计时方式不同,tick的时间单位不同
            long tick = stopWatch.ElapsedTicks;
            Console.WriteLine("RunTime(tick) " + tick);

            if (Stopwatch.IsHighResolution)
            {
                // 计时器刻度是高性能计时器滴答数
                Console.WriteLine("使用系统高分辨率性能计数器计时:");
                Console.WriteLine("  RunTime(ns) " +tick* ((1000L * 1000L * 1000L)/ Stopwatch.Frequency));
            }
            else
            {
                // 计时器刻度是DateTime.Now实例的DateTime.Ticks当前属性
                Console.WriteLine("使用DateTime类计时:");
                Console.WriteLine("  RunTime(ns) " + tick * 100);
            }

查看Stopwatch计时器的计时方式:

        /// 
        /// 显示计时器属性
        /// 
        public static void DisplayTimerProperties()
        {
            // 显示定时器频率和分辨率
            if (Stopwatch.IsHighResolution)
            {
                Console.WriteLine("操作使用系统高分辨率性能计数器计时");
            }
            else
            {
                Console.WriteLine("操作使用DateTime类计时");
            }

            long frequency = Stopwatch.Frequency;
            Console.WriteLine("  计时器频率,单位为每秒滴答数 = {0}",
                frequency);
            long nanosecPerTick = (1000L * 1000L * 1000L) / frequency;
            Console.WriteLine("  计时器分辨率为 {0} 纳秒/滴答",
                nanosecPerTick);
        }

附上官网上的一个测试实例:

        private static void TimeOperations()
        {
            long nanosecPerTick = (1000L * 1000L * 1000L) / Stopwatch.Frequency;
            const long numIterations = 10000;

            // 定义操作标题名称
            String[] operationNames = {"操作: Int32.Parse(\"0\")",
                                           "操作: Int32.TryParse(\"0\")",
                                           "操作: Int32.Parse(\"a\")",
                                           "操作: Int32.TryParse(\"a\")"};
            Console.WriteLine();
            Console.WriteLine("注:1ticks=100ns,1s=1000ms,1ms=1000us,1us=1000ns");

            // 从字符串解析整数的四种不同实现
            for (int operation = 0; operation <= 3; operation++)
            {
                // 定义操作统计的变量
                long numTicks = 0;
                long numRollovers = 0;
                long maxTicks = 0;
                long minTicks = Int64.MaxValue;
                int indexFastest = -1;
                int indexSlowest = -1;
                long milliSec = 0;

                Stopwatch time10kOperations = Stopwatch.StartNew();

                // 运行当前操作10001次。
                // 第一次执行时间将被丢弃,因为它可能会扭曲平均时间。
                for (int i = 0; i <= numIterations; i++)
                {
                    long ticksThisTime = 0;
                    int inputNum;
                    Stopwatch timePerParse;

                    switch (operation)
                    {
                        case 0:
                            // 使用try-catch语句分析有效整数
                            // 启动新的秒表计时器
                            timePerParse = Stopwatch.StartNew();
                            try
                            {
                                inputNum = Int32.Parse("0");
                            }
                            catch (FormatException)
                            {
                                inputNum = 0;
                            }

                            // 停止计时器,并保存操作所用的计时ticks

                            timePerParse.Stop();
                            ticksThisTime = timePerParse.ElapsedTicks;
                            break;
                        case 1:                           
                            timePerParse = Stopwatch.StartNew();
                            if (!Int32.TryParse("0", out inputNum))
                            {
                                inputNum = 0;
                            }
                            timePerParse.Stop();
                            ticksThisTime = timePerParse.ElapsedTicks;
                            break;
                        case 2:                            
                            timePerParse = Stopwatch.StartNew();
                            try
                            {
                                inputNum = Int32.Parse("a");
                            }
                            catch (FormatException)
                            {
                                inputNum = 0;
                            }
                            timePerParse.Stop();
                            ticksThisTime = timePerParse.ElapsedTicks;
                            break;
                        case 3:                           
                            timePerParse = Stopwatch.StartNew();
                            if (!Int32.TryParse("a", out inputNum))
                            {
                                inputNum = 0;
                            }                            
                            timePerParse.Stop();
                            ticksThisTime = timePerParse.ElapsedTicks;
                            break;
                        default:
                            break;
                    }
                    // 跳过第一个操作的时间,以防它导致一次性性能下降。
                    if (i == 0)
                    {
                        time10kOperations.Reset();
                        time10kOperations.Start();
                    }
                    else
                    {
                        // 更新迭代1-10001的操作统计信息。
                        if (maxTicks < ticksThisTime)
                        {
                            indexSlowest = i;
                            maxTicks = ticksThisTime;
                        }
                        if (minTicks > ticksThisTime)
                        {
                            indexFastest = i;
                            minTicks = ticksThisTime;
                        }
                        numTicks += ticksThisTime;
                        if (numTicks < ticksThisTime)
                        {
                            // Keep track of rollovers.
                            numRollovers++;
                        }
                    }
                }

                // 显示10000次迭代的统计信息
                time10kOperations.Stop();
                milliSec = time10kOperations.ElapsedMilliseconds;

                Console.WriteLine();
                Console.WriteLine("{0} 统计:", operationNames[operation]);
                Console.WriteLine("  最慢时间:  第{0}/{1}次操作,时间为{2} ticks",
                    indexSlowest, numIterations, maxTicks);
                Console.WriteLine("  最快时间:  第{0}/{1}次操作,时间为{2} ticks",
                    indexFastest, numIterations, minTicks);
                Console.WriteLine("  平均时间:  {0} ticks = {1} ns",
                    numTicks / numIterations,
                    (numTicks * nanosecPerTick) / numIterations);
                Console.WriteLine("  {0} 次操作的总时间: {1} ms",
                    numIterations, milliSec);
            }
        }

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