昨天对“黑色n秒”问题的最终猜想以失败而告终，从而让我们结束了被动猜想阶段，进入了主动进攻阶段——出招。
今天出第一招——用C#写个小程序，让其在每个CPU核上运行一个线程，不让任何一个CPU核进入空闲（idle）状态，以进一步排除CPU idle引起的“黑色n秒”。
在这一招中，借助的最重要的武器是System.Diagnostics.ProcessThread.ProcessorAffinity。通过给ProcessorAffinity设置一个掩码，就可以指定当前线程运行于哪个CPU核上。
如上图，用哪个核就把那个核对应的二进制位置1，其他位保持0。
所以对于我们所用的8核CPU，从第1核到第8核对应的ProcessorAffinity分别是：1, 2, 4, 8, 16, 32, 64, 128。
需要注意的地方是ProcessThread.ProcessorAffinity针对的是Windows操作系统线程，而.NET线程并不是与操作系统线程一一对应的，一个.NET线程可以运行于多个操作系统线程。所以，如果仅仅指定ProcessThread.ProcessorAffinity，并不能保证.NET线程运行于指定的CPU核上。那怎么办呢？
微软提供了解决方案，在设置ProcessThread.ProcessorAffinity之前需要通过下面的代码将.NET线程固定在操作系统线程上：
Thread.BeginThreadAffinity();
还有一个需要解决的问题是如何让一个线程一直处于执行状态，从而不让其所在的CPU核进入idle状态。微软也提供了解决方案，调用非托管方法SetThreadExecutionState()，代码如下：
NativeMethods.SetThreadExecutionState(NativeMethods.ES_CONTINUOUS | NativeMethods.ES_SYSTEM_REQUIRED);
下面请看招式：
代码第1部分：
class Program{static void Main(string[] args){var threads = new Thread[Environment.ProcessorCount];Console.WriteLine("Processor Count:" + Environment.ProcessorCount);for (int i = 0; i < threads.Length; i++){var coreNumber = i + 1;var threaName = "ThreadOnCPU" + coreNumber;var start = new ThreadStart(() =>{Console.WriteLine(threaName + " is working...");NativeMethods.SetThreadExecutionState(NativeMethods.ES_CONTINUOUS | NativeMethods.ES_SYSTEM_REQUIRED);});var thread = new DistributedThread(start);thread.ProcessorAffinity = (int)Math.Pow(2, i);thread.ManagedThread.Name = threaName;thread.Start();}Console.ReadKey();} }internal static class NativeMethods{[DllImport("kernel32.dll")]public static extern uint SetThreadExecutionState(uint esFlags);public const uint ES_CONTINUOUS = 0x80000000;public const uint ES_SYSTEM_REQUIRED = 0x00000001;}
代码第2部分（来自Running .NET threads on selected processor cores ）：
class DistributedThread{[DllImport("kernel32.dll")]public static extern int GetCurrentThreadId();[DllImport("kernel32.dll")]public static extern int GetCurrentProcessorNumber();private ThreadStart threadStart;private ParameterizedThreadStart parameterizedThreadStart;private Thread thread;public int ProcessorAffinity { get; set; }public Thread ManagedThread{get{return thread;}}private DistributedThread(){thread = new Thread(DistributedThreadStart);}public DistributedThread(ThreadStart threadStart): this(){this.threadStart = threadStart;}public DistributedThread(ParameterizedThreadStart threadStart): this(){this.parameterizedThreadStart = threadStart;}public void Start(){if (this.threadStart == null) throw new InvalidOperationException();thread.Start(null);}public void Start(object parameter){if (this.parameterizedThreadStart == null) throw new InvalidOperationException();thread.Start(parameter);}private void DistributedThreadStart(object parameter){try{// fix to OS thread Thread.BeginThreadAffinity();// set affinityif (ProcessorAffinity != 0){CurrentThread.ProcessorAffinity = new IntPtr(ProcessorAffinity);}// call real threadif (this.threadStart != null){this.threadStart();}else if (this.parameterizedThreadStart != null){this.parameterizedThreadStart(parameter);}else{throw new InvalidOperationException();}}finally{// reset affinityCurrentThread.ProcessorAffinity = new IntPtr(0xFFFF);Thread.EndThreadAffinity();}}private ProcessThread CurrentThread{get{int id = GetCurrentThreadId();return(from ProcessThread th in Process.GetCurrentProcess().Threadswhere th.Id == idselect th).Single();}}}
DistributedThread
接下来，出招——KeepAllCpuCoresAlive！
结果。。。这一招以失败告终！
（上图是“黑色1秒”发生时性能监视器监测到的 Requests/Sec为0的情况）
失败又如何，就如同代码编译不通过一般不值一提。那为什么还要写博客出来呢？分享的就是过程！
接下来呢？准备第二招。。。
【参考资料】
Running .NET threads on selected processor cores
Threading in C#
Keep Alive the Machine - No Sleep
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