public void CleanUpExpiredSessions(IUserSessionService sessionService, IErrorLog errorLog)
		{
			if (!Monitor.TryEnter(_syncRoot)) return;
			try
			{
				sessionService.CleanUpExpiredSessions();
			}
			catch (Exception exc)
			{
				errorLog.Log(exc, ErrorSeverity.Error);
			}
			finally
			{
				Monitor.Exit(_syncRoot);
			}
		}