public void getDiskSizeByDataRegion(
      Map<Integer, Long> dataRegionDisk, List<Integer> dataRegionIds) {
    dataRegionMap.forEach(
        (dataRegionId, dataRegion) -> {
          if (dataRegionIds.contains(dataRegionId.getId())) {
            dataRegionDisk.put(dataRegionId.getId(), dataRegion.countRegionDiskSize());
          }
        });
  }
reboot timed flush sequence/unsequence memtable thread
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/StorageEngine.java