首先，非常感谢赵老大的CodeTimer，它让我们更好的了解到代码执行的性能，从而可以让我们从性能的角度来考虑问题，有些东西可能我们认为是这样的，但经理测试并非如何，这正应了我之前的那名话：“机器最能证明一切”！
费话就不说了，看代码吧：
1 /// <summary> 2 /// 执行代码规范 3 /// </summary> 4 public interface IAction 5 { 6 void Action(); 7 } 8 9 /// <summary> 10 /// 老赵的性能测试工具 11 /// </summary> 12 public static class CodeTimer 13 { 14 [DllImport("kernel32.dll", SetLastError = true)] 15 static extern bool GetThreadTimes(IntPtr hThread, out long lpCreationTime, out long lpExitTime, out long lpKernelTime, out long lpUserTime); 16 17 [DllImport("kernel32.dll")] 18 static extern IntPtr GetCurrentThread(); 19 public delegate void ActionDelegate(); 20 private static long GetCurrentThreadTimes() 21 { 22 long l; 23 long kernelTime, userTimer; 24 GetThreadTimes(GetCurrentThread(), out l, out l, out kernelTime, out userTimer); 25 return kernelTime + userTimer; 26 } 27 static CodeTimer() 28 { 29 Process.GetCurrentProcess().PriorityClass = ProcessPriorityClass.High; 30 Thread.CurrentThread.Priority = ThreadPriority.Highest; 31 } 32 public static void Time(string name, int iteration, ActionDelegate action) 33 { 34 if (String.IsNullOrEmpty(name)) 35 { 36 return; 37 } 38 if (action == null) 39 { 40 return; 41 } 42 43 //1. Print name 44 ConsoleColor currentForeColor = Console.ForegroundColor; 45 Console.ForegroundColor = ConsoleColor.Yellow; 46 Console.WriteLine(name); 47 48 // 2. Record the latest GC counts 49 //GC.Collect(GC.MaxGeneration, GCCollectionMode.Forced); 50 GC.Collect(GC.MaxGeneration); 51 int[] gcCounts = new int[GC.MaxGeneration + 1]; 52 for (int i = 0; i <= GC.MaxGeneration; i++) 53 { 54 gcCounts[i] = GC.CollectionCount(i); 55 } 56 57 // 3. Run action 58 Stopwatch watch = new Stopwatch(); 59 watch.Start(); 60 long ticksFst = GetCurrentThreadTimes(); //100 nanosecond one tick 61 for (int i = 0; i < iteration; i++) action(); 62 long ticks = GetCurrentThreadTimes() - ticksFst; 63 watch.Stop(); 64 65 // 4. Print CPU 66 Console.ForegroundColor = currentForeColor; 67 Console.WriteLine("\tTime Elapsed:\t\t" + 68 watch.ElapsedMilliseconds.ToString("N0") + "ms"); 69 Console.WriteLine("\tTime Elapsed (one time):" + 70 (watch.ElapsedMilliseconds / iteration).ToString("N0") + "ms"); 71 Console.WriteLine("\tCPU time:\t\t" + (ticks * 100).ToString("N0") 72 + "ns"); 73 Console.WriteLine("\tCPU time (one time):\t" + (ticks * 100 / 74 iteration).ToString("N0") + "ns"); 75 76 // 5. Print GC 77 for (int i = 0; i <= GC.MaxGeneration; i++) 78 { 79 int count = GC.CollectionCount(i) - gcCounts[i]; 80 Console.WriteLine("\tGen " + i + ": \t\t\t" + count); 81 } 82 Console.WriteLine(); 83 } 84 85 86 87 public static void Time(string name, int iteration, IAction action) 88 { 89 if (String.IsNullOrEmpty(name)) 90 { 91 return; 92 } 93 94 if (action == null) 95 { 96 return; 97 } 98 99 //1. Print name 100 ConsoleColor currentForeColor = Console.ForegroundColor; 101 Console.ForegroundColor = ConsoleColor.Yellow; 102 Console.WriteLine(name); 103 104 // 2. Record the latest GC counts 105 //GC.Collect(GC.MaxGeneration, GCCollectionMode.Forced); 106 GC.Collect(GC.MaxGeneration); 107 int[] gcCounts = new int[GC.MaxGeneration + 1]; 108 for (int i = 0; i <= GC.MaxGeneration; i++) 109 { 110 gcCounts[i] = GC.CollectionCount(i); 111 } 112 113 // 3. Run action 114 Stopwatch watch = new Stopwatch(); 115 watch.Start(); 116 long ticksFst = GetCurrentThreadTimes(); //100 nanosecond one tick 117 for (int i = 0; i < iteration; i++) action.Action(); 118 long ticks = GetCurrentThreadTimes() - ticksFst; 119 watch.Stop(); 120 121 // 4. Print CPU 122 Console.ForegroundColor = currentForeColor; 123 Console.WriteLine("\tTime Elapsed:\t\t" + 124 watch.ElapsedMilliseconds.ToString("N0") + "ms"); 125 Console.WriteLine("\tTime Elapsed (one time):" + 126 (watch.ElapsedMilliseconds / iteration).ToString("N0") + "ms"); 127 Console.WriteLine("\tCPU time:\t\t" + (ticks * 100).ToString("N0") 128 + "ns"); 129 Console.WriteLine("\tCPU time (one time):\t" + (ticks * 100 / 130 iteration).ToString("N0") + "ns"); 131 132 // 5. Print GC 133 for (int i = 0; i <= GC.MaxGeneration; i++) 134 { 135 int count = GC.CollectionCount(i) - gcCounts[i]; 136 Console.WriteLine("\tGen " + i + ": \t\t\t" + count); 137 } 138 Console.WriteLine(); 139 } 140 }
有了上面的codeTimer我们就来测试一个吧，如字条串和并的问题，用+=还是用StringBuilder呢，有点经验的程序员肯定说是StringBuilder，是的，确实是后者，那我们就来看看这
两种方法测试的结果吧
1 CodeTimer.Time("String Concat", 100000, 2 () => 3 { 4 var s = "1"; 5 for (int i = 1; i < 10; i++) 6 s = s + "1"; 7 }); 8 9 CodeTimer.Time("StringBuilder Concat", 100000, 10 () => 11 { 12 var s = new StringBuilder(); 13 for (int i = 1; i < 10; i++) 14 s.Append("1"); 15 });
测试的结果如下：
从图中我们可以看到StringBuilder快的很明显，无论是执行时间，还是对CPU的消耗及GC回收都远低于String的拼结，所以，才有以下结论：
在字符串拼结时，请使用StringBuilder吧！
本文转自博客园张占岭（仓储大叔）的博客，原文链接：将不确定变为确定~老赵写的CodeTimer是代码性能测试的利器，如需转载请自行联系原博主。
