code: @Override
    public void doUpdates(MetricsContext unused) {
      synchronized (this) {
        for (MetricsBase m : registry.getMetricsList()) {
          m.pushMetric(metricsRecord);
        }
      }
      metricsRecord.update();
    }
docs: Since this object is a registered updater, this method will be called
  periodically, e.g. every 5 seconds.