private static Timer timer;
private static readonly object _syncLock = new object();
protected void Application_Start()
{
            if (timer == null)
            {
                lock (_syncLock)
                {
                    if (timer == null)
                    {
                        timer = new Timer(WriterFile, null, 0, 30 * 1000);                        
                    }
                }

            }
}
private void WriterFile(object state)
        {
            FileStream fs = null;
            StreamWriter sw = null;
            try
            {
                string path = @"D:\aspnet\MvcApplication5\MvcApplication5";
                fs = new FileStream( path+"\\test.txt",FileMode.Append, FileAccess.Write);
                sw=new StreamWriter(fs);
                sw.WriteLine(new Random().Next(1, 101));
            }
            catch (Exception ee)
            {

            }
            finally
            {
                if (sw != null)
                {
                    sw.Dispose();
                }
                if (fs != null)
                {
                    fs.Dispose();
                }
            }
        }