code: static void reportError(final String errorMessage) {
          if (MetricsManager.instance != null) {
              MetricsManager.rootMetricsLogger.incCounter(METRIC_ERRORS, 1);
          }
          LOG.error(errorMessage);
      }
docs: Report errors during metric data collecting process. Report in two forms, a host level metric which counts
  number of errors and a log line with message for each error. Will be used by MetricsLogger to report errors.
  
  @param errorMessage, error message during metric data collecting process