protected ISchemaPage registerAsNewPage(ISchemaPage page, SchemaPageContext cxt) {
    // new page will be LOCAL until the creating thread finished
    //  thus not added to sparsePageIndex now
    page.setPageIndex(lastPageIndex.incrementAndGet());
    pagePool.put(page);
    cxt.markDirty(page);
    return page;
  }
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