memory leak in a MFC application

ssylee

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Mar 25, 2009, 6:42:04 PM3/25/09

to

I have a single-document view MFC application as attached to this link
(https://www.yousendit.com/download/UmNMZGVkNEhkMnV4dnc9PQ). This
application would need to link with OpenGL libraries and dlls in order
to run. In addition, Intel Math Kernel Library (or Intel Compiler)
needs to be installed on the system in order for the application to
run.

My memory leak problem, at least I found, has something to do with
this snippet in CsplitterView::OnTimer handler:

if(startsim && needlemodel)
{
//theMesh->NodesRepoint(needlemodel->Xall);
theMesh->nodesdeleteignore = true; // change this parameter's
scope back to private
startsim = false;
}

if (theMesh->nodesdeleteignore &&
needlemodel)
{
if (count < needlemodel->needleBasePos.entries)
{
needlemodel->DoNeedle(&(needlemodel->needleBasePos.nodepts
[6*count]));
count++;
}
}

If "needlemodel->DoNeedle(&(needlemodel->needleBasePos.nodepts
[6*count]));" gets commented out, I don't see any memory leak problem
showing up in the debug window. If that function is called on a
consistent basis as the "Start" button in the application is pressed,
as I close the window, I see a group of memory leak messages from
Visual Studio debug output as indicated:

Detected memory leaks!
Dumping objects ->
{898} normal block at 0x04415428, 480128 bytes long.
Data: < > CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD
CD
{897} normal block at 0x02E4F8C0, 13184 bytes long.
Data: < > CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD
CD
{896} normal block at 0x02E4C380, 120 bytes long.
Data: < (TA > C0 F8 E4 02 28 54 41 04 00 00 00 00 00 00 00
00
{895} normal block at 0x02E4C500, 13184 bytes long.
Data: < > CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD
CD
{894} normal block at 0x046A0040, 935040 bytes long.
Data: < > CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD
CD
{889} normal block at 0x043A0068, 480128 bytes long.
Data: < > CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD
CD
{888} normal block at 0x02E4C448, 120 bytes long.
Data: <h : @ j > 68 00 3A 04 40 00 6A 04 00 C5 E4 02 00 00 00
00
Object dump complete.

I have used the memory profiler as well as data debug point in Visual
Studio debugger to check when the data in any one of the addresses as
indicated in the previous message change. However, I have found them
to be changing and allocated in Microsoft-implemented function calls
that I have no idea of. I suspect I'm using the MFC API improperly
somewhere in the project, but I have no idea what. After doing some
search on the internet, I have tried setting a breakpoint on a memory
allocation number (http://msdn.microsoft.com/en-us/library/w2fhc9a3(VS.
80).aspx), but have not much luck either.

When I ran the same function in a separate console project, I don't
see the same errors in the debug output window. You can try running it
for yourselves as I have attached the project to this link (https://
www.yousendit.com/download/UmNMZGVYQzNEa1ZjR0E9PQ). Again, Intel Math
Kernel Library needs to be installed before this application can be
run properly.

Sorry for the long email. Would really appreciate the explanation of
what's going on.

Goran

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Mar 26, 2009, 4:14:37 AM3/26/09

to

It's really not possible to conclude anything from your description.

Warning: potentially pointless patronizing ahead:

Let's say that memory leaks have a source and a destination. Let's
also say that source is a place where memory is allocated, and that
destination is the place where, by the program design, it should be
freed. One can't make a correct program without sorting this out for
every single allocation in the code.

That said... You are still far away from the source of the leak, and
from there, you need to find the destination. Who has the source
of ::DoNeedle? If you, you should dig into this function first, then
go from there.

Goran.

AliR (VC++ MVP)

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Mar 26, 2009, 11:09:17 AM3/26/09

to

Have you looked at DoNeedle to make sure it doesn't leak memory?

AliR.

"ssylee" <stani...@gmail.com> wrote in message
news:0ceb22f9-f24e-4294...@k19g2000prh.googlegroups.com...

ssylee

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Mar 26, 2009, 12:52:55 PM3/26/09

to

On Mar 26, 8:09 am, "AliR $VC++ MVP$" <A...@online.nospam> wrote:
> Have you looked at DoNeedle to make sure it doesn't leak memory?
>
> AliR.
>

> "ssylee" <staniga...@gmail.com> wrote in message

Thanks for your replies. I have actually run DoNeedle function in the
application in the second link in a console window, in exactly the
same manner. I did not see any memory leak complaints from the debug
output, and I have done my due diligence to ensure malloc/free or new/
delete are paired properly in the DoNeedle function.

BobF

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Mar 26, 2009, 1:13:31 PM3/26/09

to

<http://msdn.microsoft.com/en-us/visualc/cc563920.aspx>

<http://msdn.microsoft.com/en-us/library/aa293901(VS.60).aspx>

<http://msdn.microsoft.com/en-us/library/x98tx3cf(VS.80).aspx>

Joseph M. Newcomer

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Mar 26, 2009, 3:16:13 PM3/26/09

to

Your evaluation suggests that DoNeedle is the source of the problem. If you can do
something that produces the *same* values, {898} for example, then you can find the source
of the leak fairly easily.

Use the debugger to set the variable _crtBreakAlloc to the number you see (898 in the
example below) and you will get a debug break when that is allocated. Track back in the
stack to see who is allocating it. and you will know what allocation is not being freed.

Note that a lot of the files generate by Microsoft include the declaration

#ifdef _DEBUG
#define new DEBUG_NEW
#endif

If you are writing files that were not generated by the wizards, add those lines at the
front, and you will get the filename/line info in your debug report.
joe

Joseph M. Newcomer [MVP]
email: newc...@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm

ssylee

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Mar 26, 2009, 6:37:58 PM3/26/09

to

> email: newco...@flounder.com

> Web:http://www.flounder.com
> MVP Tips:http://www.flounder.com/mvp_tips.htm

Thanks for the videos and links in terms of memory leak finding
tutorials. I have added the MFC CMemoryState object instantiation and
method calls in the following manner in splitterView.cpp where
DoNeedle is being called:

if(startsim && needlemodel)
{
//theMesh->NodesRepoint(needlemodel->Xall);
theMesh->nodesdeleteignore = true; // change this parameter's
scope back to private
startsim = false;
}

if (theMesh->nodesdeleteignore &&
needlemodel)
{
if (count < needlemodel->needleBasePos.entries)
{

#if _DEBUG
CMemoryState oldstate, newstate, diffstate;
oldstate.Checkpoint();
#endif

// Note: memory leak indeed comes from this function
// need to determine the meaning of the memory leak diagnostics

needlemodel->DoNeedle(&(needlemodel->needleBasePos.nodepts
[6*count]));
count++;

#if _DEBUG
newstate.Checkpoint();
if(diffstate.Difference(oldstate, newstate))
{
AfxMessageBox("Memory Leak Detected");
diffstate.DumpAllObjectsSince();
}
#endif
}
}

The message box does pop up on certain calls to DoNeedle function.
However, as I step through the code inside DoNeedle in the debugger on
the cases where the memory state has changed, I can't find any new
memory allocations (at least the one that I have made anyway). I am
extremely certain that all the malloc/free pairs in the DoNeedle
function are paired properly in the Needle3D class from my search in
that project. There are no new/delete pairs in the Needle3D class. I
have no knowledge in terms of context of the additional new operator
calls that are called. Below is the printout of the
DumpAllObjectsSince function during a particular instance.

Dumping objects ->
{661} normal block at 0x119B58C8, 480128 bytes long.