🚀 go-pugleaf

Here is something that Jim Champeaux discovered here at Mirror Systems.  I
am curious to learn if anyone else has experienced similar problems.

The basic problem is that calling MakeProcInstance() when it is not needed
[even though Microsoft says it is OK but not necessary to call
MakeProcInstance() in our particular case] even with matching
FreeProcInstance() calls ends up slowly using up all of free memory.  It
appears that each call to MakeProcInstance() and FreeProcInstance() uses up
96 bytes of global memory.  Our program was crashing due to insufficient free
memory after about 4000 iterations through the code that contained the
MakeProcInstance() and FreeProcInstance() calls.  Removing the unnecessary
MakeProcInstance() and FreeProcInstance() calls solved the memory loss
problem.  We reported this to Microsoft via On-Line but we have not yet heard
anything from them.
                                                                    Marc
----
	      "All my life I always wanted to BE somebody.
	       I see now I should have been more specific."
			     Jane Wagner
Marc Guyott					    mguyott@mirror.tmc.com
{mit-eddie, pyramid, harvard!wjh12, xait}!mirror!mguyott
Mirror Systems		 Cambridge, MA	02140	       617/661-0777

----

/* Written  2:01 pm  Dec  4, 1989 by jvc@prism.TMC.COM */
/* ---------- "Global Memory Loss" ---------- */
Read this if your are experiencing global memory loss.

According to Microsoft, MakeProcInstance() "is not required if the
module has a single data segment for all instances".  DLLs are
such a creature.  However, it seems their wording is not strong
enough.  We (tools group) have found that it might actually be
detrimental to use MakeProcInstance() in a DLL.

WinTester had this problem of eating up global memory.  It would
keep allocating 96 byte blocks of memory to support a linked list.
From what we can tell this linked list contained nothing but nulls.
In our case, we were also not using FreeProcInstance() since Microsoft
also states "MakeProcInstance can create no more than one procedure
instance of an application.  This means that after a procedure instance
has been created, subsequent calls using the same function and instance
return the same result.".  We only had four or five functions which needed
(we thought) procedure instance addresses and these functions were called
repeatedly.  Well, we installed FreeProcInstance() in all locations 
appropriate and the same problem continued.

We finally removed the MakeProcInstance()/FreeProcInstance() calls
(remember, Microsoft said they weren't required) and used the address
of the function directly.  Problem solved, no more eating global
memory.
/* End of text from prism:ms.clps.common */