ASP.NET Thread Pool 監控

前情提要

上一次說明了 .NET Thread Pool 的機制如何影響 Redis,
.NET Thread Pool 的機制會貫穿任何與它互動的系統或服務,
所以這篇會簡單描述如何對 .NET Thread Pool 建立監控。

步驟

1. 建立監控記數器
2. 在系統寫入監控數值
3. 開啟效能計數器

建立監控記數器

記數器	說明
Available Worker Threads	目前在 thread-pool 可以使用的 worker threads
Available IO Threads	目前在 thread-pool 可以使用的 I/O threads
Max Worker Threads	最大可以建立的 worker threads 數量
Max IO Threads	最大可以建立的 I/O threads 數量

建立一個 Console 應用程式

using System;
using System.Diagnostics;

class MyAspNetThreadCounters
{
  [STAThread]
  static void Main(string[] args)
  {
    CreateCounters();
    Console.WriteLine("MyAspNetThreadCounters performance counter category " +
                      "is created. [Press Enter]");
    Console.ReadLine();
  }

  public static void CreateCounters()
  {
    CounterCreationDataCollection col =
      new CounterCreationDataCollection();

    // Create custom counter objects
    CounterCreationData counter1 = new CounterCreationData();
    counter1.CounterName = "Available Worker Threads";
    counter1.CounterHelp = "The difference between the maximum number " +
                           "of thread pool worker threads and the " +
                           "number currently active.";
    counter1.CounterType = PerformanceCounterType.NumberOfItems32;

    CounterCreationData counter2 = new CounterCreationData();
    counter2.CounterName = "Available IO Threads";
    counter2.CounterHelp = "The difference between the maximum number of " +
                           "thread pool IO threads and the number "+
                           "currently active.";
    counter2.CounterType = PerformanceCounterType.NumberOfItems32;

    CounterCreationData counter3 = new CounterCreationData();
    counter3.CounterName = "Max Worker Threads";
    counter3.CounterHelp = "The number of requests to the thread pool "+
                           "that can be active concurrently. All "+
                           "requests above that number remain queued until " +
                           "thread pool worker threads become available.";
    counter3.CounterType = PerformanceCounterType.NumberOfItems32;

    CounterCreationData counter4 = new CounterCreationData();
    counter4.CounterName = "Max IO Threads";
    counter4.CounterHelp = "The number of requests to the thread pool " +
                           "that can be active concurrently. All "+
                           "requests above that number remain queued until " +
                           "thread pool IO threads become available.";
    counter4.CounterType = PerformanceCounterType.NumberOfItems32;

    // Add custom counter objects to CounterCreationDataCollection.
    col.Add(counter1);
    col.Add(counter2);
    col.Add(counter3);
    col.Add(counter4);
    // delete the category if it already exists
    if(PerformanceCounterCategory.Exists("MyAspNetThreadCounters"))
    {
      PerformanceCounterCategory.Delete("MyAspNetThreadCounters");
    }
    // bind the counters to the PerformanceCounterCategory
    PerformanceCounterCategory category =
            PerformanceCounterCategory.Create("MyAspNetThreadCounters",
                                              "", col);
  }
}

編譯後並執行即可,
執行 regedit 開啟登錄編輯程式,
輸入機碼 HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
將可以找到剛剛建立的 MyAspNetThreadCounters 記數器

在系統寫入監控數值

在站台的 Global.asax 加入以下的程式碼

public bool MonitorThreadPoolEnabled = true;

protected void Application_Start(Object sender, EventArgs e)
{
  Thread t = new Thread(new ThreadStart(RefreshCounters));
  t.Start();
}

public void RefreshCounters()
{
  while (MonitorThreadPoolEnabled)
  {
    ASPNETThreadInfo t = GetThreadInfo();
    ShowPerfCounters(t);
    System.Threading.Thread.Sleep(500);
  }
}

protected void Application_End(Object sender, EventArgs e)
{
  MonitorThreadPoolEnabled = false;
}

public struct ASPNETThreadInfo
{
  public int MaxWorkerThreads;
  public int MaxIOThreads;
  public int MinFreeThreads;
  public int MinLocalRequestFreeThreads;
  public int AvailableWorkerThreads;
  public int AvailableIOThreads;

  public bool Equals(ASPNETThreadInfo other)
  {
    return (
      MaxWorkerThreads == other.MaxWorkerThreads &&
      MaxIOThreads == other.MaxIOThreads &&
      MinFreeThreads == other.MinFreeThreads &&
      MinLocalRequestFreeThreads == other.MinLocalRequestFreeThreads &&
      AvailableWorkerThreads == other.AvailableWorkerThreads &&
      AvailableIOThreads == other.AvailableIOThreads
    );
  }
}

public ASPNETThreadInfo GetThreadInfo()
{
  // use ThreadPool to get the current status
  int availableWorker, availableIO;
  int maxWorker, maxIO;

  ThreadPool.GetAvailableThreads( out availableWorker, out availableIO);
  ThreadPool.GetMaxThreads(out maxWorker, out maxIO);

  ASPNETThreadInfo threadInfo;
  threadInfo.AvailableWorkerThreads = (Int16)availableWorker;
  threadInfo.AvailableIOThreads = (Int16)availableIO;
  threadInfo.MaxWorkerThreads = (Int16)maxWorker;
  threadInfo.MaxIOThreads = (Int16)maxIO;
 // hard code for now; could get this from  machine.config
  threadInfo.MinFreeThreads = 8;
  threadInfo.MinLocalRequestFreeThreads = 4;
  return threadInfo;
}

public void ShowPerfCounters(ASPNETThreadInfo t)
{

  // get an instance of our Available Worker Threads counter
  PerformanceCounter counter1 = new PerformanceCounter();
  counter1.CategoryName = "MyAspNetThreadCounters";
  counter1.CounterName = "Available Worker Threads";
  counter1.ReadOnly = false;

  // set the value of the counter
  counter1.RawValue = t.AvailableWorkerThreads;
  counter1.Close();

  // repeat for other counters

  PerformanceCounter counter2 = new PerformanceCounter();
  counter2.CategoryName = "MyAspNetThreadCounters";
  counter2.CounterName = "Available IO Threads";
  counter2.ReadOnly = false;
  counter2.RawValue = t.AvailableIOThreads;
  counter2.Close();

  PerformanceCounter counter3 = new PerformanceCounter();
  counter3.CategoryName = "MyAspNetThreadCounters";
  counter3.CounterName = "Max Worker Threads";
  counter3.ReadOnly = false;
  counter3.RawValue = t.MaxWorkerThreads;
  counter3.Close();

  PerformanceCounter counter4 = new PerformanceCounter();
  counter4.CategoryName = "MyAspNetThreadCounters";
  counter4.CounterName = "Max IO Threads";
  counter4.ReadOnly = false;
  counter4.RawValue = t.MaxIOThreads;
  counter4.Close();
}

當你的站台重新啟動後,
就會定期將 Worker Thread 與 I/O Threads 的監控數值傳遞給系統。

開啟效能計數器

1. 執行 perfmon.exe 開啟效能計數器
2. 新增效能計數器(點選綠色加符號)
3. 選取前面所建立監控記數器就能看到當前 ThreadPool 的使用狀況。
   

(fin)