protected ISchemaPage allocNewSegmentedPage(SchemaPageContext cxt)
      throws SegmentNotFoundException {
    ISchemaPage newPage =
        ISchemaPage.initSegmentedPage(
            ByteBuffer.allocate(SchemaFileConfig.PAGE_LENGTH), lastPageIndex.incrementAndGet());
    // lock and mark to be consistent with # getMinApplSegmentedPageInMem
    cxt.markDirty(newPage);
    newPage.getLock().writeLock().lock();
    cxt.traceLock(newPage);
    pagePool.put(newPage);
    return newPage;
  }
Only accessed during write operation and every page returned is due to be modified thus they
are all marked dirty.

@param size size of the expected segment
@return always write locked
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/mtree/impl/pbtree/schemafile/pagemgr/PageManager.java