private void updateAssignmentManagerMetrics(final HbckReport report) {
    master.getAssignmentManager().getAssignmentManagerMetrics()
      .updateOrphanRegionsOnRs(report.getOrphanRegionsOnRS().size());
    master.getAssignmentManager().getAssignmentManagerMetrics()
      .updateOrphanRegionsOnFs(report.getOrphanRegionsOnFS().size());
    master.getAssignmentManager().getAssignmentManagerMetrics()
      .updateInconsistentRegions(report.getInconsistentRegions().size());
  }
Scan hbase:meta to get set of merged parent regions, this is a very heavy scan.
@return Return generated {@link HashSet}
hbase-server/src/main/java/org/apache/hadoop/hbase/master/hbck/HbckChore.java