Problems in Memory Handling with MSXML

Question

I've got an application for testing fabricated products using some legacy code in an dll. The application could be set up for different products. The setup is done via xml-files and can (and will) be changed during runtime, i.e. at End-Of-Lot. The processing of the xml is done by the mentioned legacy dll.

After running over a longer time (days to weeks) I've noticed an increasing memory footprint. Debugging into that, I could trace the (possible) leak to the dll. After getting the source, I could further investigate till I found something like this:

CAObjHandle doc;
MSXML6_NewDOMDocument40IXMLDOMDocument2(0, 0, LOCALE_NEUTRAL, 0, &doc);
[...]
MSXML6_IXMLDOMDocument2load(doc, 0, vtPath, &success);

It seems to me, this is called every time, a new lot is started. And it's this doc structure, that seems to reside in memory. I don't find any place where it is freed.

After all, the dll had a lot of minor leaks, all from not freed objects (of CVI-functions). I fixed those, but I don't know, how to free this MS-Objects. I came across this: Understanding the MSXML garbage collection mechanism, but after I have ANSI-C code, I'm not sure, what to do with GC and wether it works or not.

Is there a way, to free MSXML-Objects manually?

Answer 1

Okay, found the answer. A MSXML6_* object could be deallocated with CA_DiscardObjHandle().