protected void Session_Start(Object sender, EventArgs e)
		{
			
            LogHelper.LogBasePath = Request.MapPath("/Log/");
        }
protected void Application_Error(Object sender, EventArgs e)
		{
            if (string.IsNullOrEmpty(LogHelper.LogBasePath))
            {
                LogHelper.LogBasePath = Request.MapPath("/Log/");
            }
            LogHelper.ExceptonInfoQueue.Enqueue(Server.GetLastError().ToString());
            Response.Redirect("/Error.aspx");
		}

 public class LogHelper
    {
        public static Queue<string> ExceptonInfoQueue = new Queue<string>();
        public static string LogBasePath;
        static LogHelper()
        {
            ThreadPool.QueueUserWorkItem(o =>
            {
                while (true)
                {

                    if (ExceptonInfoQueue.Count > 0)
                    {
                        string str = ExceptonInfoQueue.Dequeue();
                        //写入错误信息
                        string strFileName = DateTime.Now.ToString(@"\yyyy-MM-dd") + ".txt";
                        string absoluteFileName = Path.Combine(LogBasePath, strFileName);
                        lock (ExceptonInfoQueue)
                        {
                            using (FileStream fs = new FileStream(absoluteFileName, FileMode.Append, FileAccess.Write))
                            {
                                byte[] data = Encoding.Default.GetBytes(str);
                                fs.Write(data, 0, data.Length);
                            }
                        }
                    }

                }
            });
        }
    }