ts, the backend is guaranteed
          not to be accessed from other threads, unless the access is done through
          another frontend or a direct reference to the backend. This feature can
          be useful if there is a need to perform some updates on the sink backend
          while other threads may be writing logs. Beware, though, that while the
          backend is locked any other thread that tries to write a log record to
          the sink gets blocked until the backend is released.
        