@Override
  public long getHeapSize() {
    long result = 0;
    for (ImmutableSegment s : segments) {
      result += s.getHeapSize();
    }
    return result;
  }
Returns The heap size of this segment.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/CompositeImmutableSegment.java