Thread Monitor class in c#
if (Id == "")
{
    System.Threading.Monitor.Enter(this);
    try
    {
        if (Request.AcceptTypes == null)
        {
            queue.Enqueue(Request.QueryString["sessionid"].Value);

            string que = "";

            que = queue.Dequeue();
            TypeController.session_id = que;
            langStr = SessionDatabase.Language;
            filter = new AllThingzFilter(SessionDatabase, parameters, langStr);
            TypeController.session_id = "";

            filter.Execute();
            Request.Clear();

            return filter.XML;
        }
        else
        {
            TypeController.session_id = "";
            filter = new AllThingzFilter(SessionDatabase, parameters, langStr);

            filter.Execute();
        }
    }
    finally
    {
        System.Threading.Monitor.Exit(this);
    }
}