public void reloadMetricProperties(TrimProperties properties) {
    ReloadLevel reloadLevel = MetricConfigDescriptor.getInstance().loadHotProps(properties, false);
    LOGGER.info("Reload metric service in level {}", reloadLevel);
    if (reloadLevel == ReloadLevel.RESTART_INTERNAL_REPORTER) {
      IoTDBInternalReporter internalReporter;
      if (MetricConfigDescriptor.getInstance().getMetricConfig().getInternalReportType()
          == InternalReporterType.IOTDB) {
        internalReporter = new IoTDBInternalLocalReporter();
      } else {
        internalReporter = new IoTDBInternalMemoryReporter();
      }
      MetricService.getInstance().reloadInternalReporter(internalReporter);
    } else {
      MetricService.getInstance().reloadService(reloadLevel);
    }
  }
load a property file and set TsfileDBConfig variables.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/conf/IoTDBDescriptor.java