@Override
    public void close() {
      if (isLocked) {
        lockManager.stampedReadUnlock(parent, readLockStamp);
        if (needLock) {
          lockManager.globalReadUnlock();
        }
        isLocked = false;
      }
    }
Since any node R/W operation may change the memory status, thus it should be controlled during
iterating child nodes.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/mtree/impl/pbtree/CachedMTreeStore.java