thank you.
Generally, after parsing the xml, the application memory caches the text information in the xml file, and there is no need to retain libxml resources such as xml node, and the xml will not be parsed again in the future, so malloc_trim can be called to force the release of the heap memory. I think many scenarios are This is the case, generally after calling libxml to complete the document parsing, save the saved information, and then do not need xml resources, libxml2 should design a function to release the heap memory requested by xmlreadfile.