public static void RefreshActiveSessions() { lock (_lockObj) { _marketsOff = new List <string>(); DatabaseMethods db = new DatabaseMethods(); _DaysOff = db.GetAllDaysOff(); foreach (var day in _DaysOff) { if (!_marketsOff.Contains(day.ExchangeID)) { _marketsOff.Add(day.ExchangeID); } } } }