@Override
  protected void chore() {
    try {
      this.master.getMasterWalManager().updateOldWALsDirSize();
    } catch (IOException e) {
      LOG.error("Got exception while trying to update the old WALs Directory size counter: "
        + e.getMessage(), e);
    }
  }
This chore is used to update the 'oldWALsDirSize' variable in {@link MasterWalManager} through
the {@link MasterWalManager#updateOldWALsDirSize()} method.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/OldWALsDirSizeChore.java