public synchronized void flushMultiPages(SchemaPageContext cxt) throws IOException {
    flushDirtyPagesStrategy.apply(
        cxt.referredPages.values().stream()
            .filter(ISchemaPage::isDirtyPage)
            .collect(Collectors.toList()));
  }
Load bytes from log, deserialize and flush directly into channel, return current length
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/mtree/impl/pbtree/schemafile/pagemgr/PageIOChannel.java