I'm using xml messages for various communications in my application.

The application is multithreaded and some of the more complicated 
interactions have IXMLDOMDoc messages being handed from one thread to 
another and destroyed by the other thread when done (the messages are 
too large and numerous to be translating the whole DOM to string form 
and back again).

I have a handle leak which I can demonstrate with the code below:

===============================================================
===============================================================
#include "msxml2.h" // Linker includes msxml2.lib

DWORD WINAPI TestThread(LPVOID blah)
{
	CoInitialize(NULL); // +2 handles

	CComPtr <IXMLDOMDocument> xmlDomDoc2;
	xmlDomDoc2.CoCreateInstance(L"MSXML2.DOMDocument.3.0", NULL, 
CLSCTX_INPROC_SERVER); // +4 handles
	xmlDomDoc2.Release(); // -0 handles

	CoUninitialize(); // -0 handles

	return 0;
}


void SmartPointerXMLDOMDocTest()
{
	// Start off with 44 handles

	CoInitialize(NULL); // +9 handles

	CComPtr <IXMLDOMDocument> xmlDomDoc1;
	xmlDomDoc1.CoCreateInstance(L"MSXML2.DOMDocument.3.0", NULL, 
CLSCTX_INPROC_SERVER); // +20 handles
	xmlDomDoc1.Release(); // -0 handles

	DWORD threadID = NULL;
	CreateThread(NULL, NULL, TestThread, NULL, 0, &threadID); // +1 
handle

	Sleep(5000); // Allow time for thread to complete (which it does).

	CoUninitialize(); // -25 handles

	// End with 55 handles
}

===================================================================
===================================================================


Every time a new thread creates an IXMLDOMDoc it allocates handles which 
are not cleaned up until every thread calls CoUninitialize.

You can't call CoUninitialize until your not going to use the IXMLDOMDoc 
again.

This means that if _any_ thread holds onto one of these docs, then 
_none_ of the other threads' handles are ever cleaned up.

This would be fine, but some parts of the app use XML for storage, not 
just message passing, so they may never let go of their xml docs until 
the app is finished.

At the rate my app passes messages, I can pick up about 50k handles in a 
few minutes.


I've been at this for weeks, so flames are fine as long as something 
useful comes of it.


-BB