IIS 7 : To Execute function/code for very first request only

//In Following method call to FirstRequestInitialization is done every time beginRequest called for a Application.
protected void Application_BeginRequest(Object source, EventArgs e)
{
    HttpApplication app = (HttpApplication)source;
    HttpContext context = app.Context;

    // Attempt to peform first request initialization
    FirstRequestInitialization.Initialize(context);
}


//Following Class will check the Flag(s_InitializedAlready) and according that it will execute Initializer function and check that request comes for first time or not.
class FirstRequestInitialization
{
    private static bool s_InitializedAlready = false;
    private static Object s_lock = new Object();

    // Initialize only on the first request
    public static void Initialize(HttpContext context)
    {

       if (s_InitializedAlready)
       {
          return;
       }

       lock (s_lock)
       {
           if (s_InitializedAlready)
           {
               return;
           }

          // write your code here for first-request initialization ...
      }

   }
}