@Override
  public long heapSize() {
    // this does not take into account row locks, recent flushes, mvcc entries, and more
    return DEEP_OVERHEAD + stores.values().stream().mapToLong(HStore::heapSize).sum();
  }
Attach {@link RegionReplicationSink#add} to the mvcc writeEntry for replicating to region
replica.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java