CODEWITHSUNDEEP
c++visual-studio-2012memory-leaks
roalter
roalter

Reputation: 259

Locating Memory Leaks

I'm currently in debuging some code, removing or at least locating memory leaks using Visual Studio 2012 with CrtDbg.

The problem is, as long as the allocation number does not change, tracking down the allocation is rather easy. When the allocation number changes a lot (or is not really deterministic), how can I locate the allocation point of that leak? Can I a least say, which module was allocating the memory?

I have following lines on shutdown of the application:

Detected memory leaks!
Dumping objects ->
{2789444} normal block at 0x0000000006103CB0, 32 bytes long.
 Data: < q f            > B8 71 E4 66 00 00 00 00 00 00 00 00 00 00 00 00 
{1269709} normal block at 0x000000000A50C6A0, 1008 bytes long.
 Data: <        )       > 01 00 00 00 0B 00 00 00 29 00 00 00 CD CD CD CD 
...
{2194} normal block at 0x0000000000278060, 16 bytes long.
 Data: <                > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
Object dump complete.

The last allocation number, 2194, is reproducable and is related to a static initializer. But the other numbers are changing.

Can't I use the address to locate it? Or is there a simpler solution to it?

Help would be great.

Upvotes: 4

Views: 1207

Answers (4)

ars
ars

Reputation: 707

You can use these technique:

#define _CRTDBG_MAP_ALLOC
#include <stdlib.h>
#include <crtdbg.h>
class MemChecker 
{
   friend class foo;
   struct foo 
   {
      HANDLE hLogFile;
      _CrtMemState _ms; 

      foo() 
      {
         hLogFile = CreateFile(TEXT("memory_leaks.txt"), GENERIC_WRITE, FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);

         _CrtSetReportMode( _CRT_WARN, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG); // enable file output
         _CrtSetReportFile( _CRT_WARN, hLogFile ); // set file to stdout
         _CrtMemCheckpoint(&_ms); // now forget about objects created before

         // breaks on N-th memory allocation
         // look for this number in report file (in curved brackets)
         //_CrtSetBreakAlloc(1518);
      }
      ~foo() 
      { 
         _CrtMemDumpAllObjectsSince(&_ms); // dump leaks
         CloseHandle(hLogFile);
      }
   };
   static foo obj;
};
MemChecker::foo MemChecker::obj;

with this declaration, every time you run your programm memory leaks will be detected and reported in a proper way.

Also, you can set breakpoint to a particularly memory leak (read the comments in code). How to do that: you run application, see, what the number of memory leak, then you set _CrtSetBreakAlloc(2789444*), so next time you run the app - it breaks on the place, where the memory (that leaked) was allocated.

You can read more carefully about flags _CRTDBG_MODE_FILE, _CRTDBG_MODE_DEBUG, to specify the place, where debug messages will be outputed.

*from your example, {2789444} normal block at 0x0000000006103CB0, 32 bytes long.

Upvotes: 0

Matt
Matt

Reputation: 6050

Try the Debug Diagnostic Tool v2.0, it is a very good memory dector tool on Windows, it is from Microsoft and it is free.

If the 3rd party libraries leaks memory, the tool can locate the library, just without the call stack information.

To start the exe via this debugger, go to the menu 'Tools'->"Pre-Attach Configuration', enable pre attach debugger for your exe.

Upvotes: 1

barak manos
barak manos

Reputation: 30126

Download visual-leak-detector and commence the following:

Create the following directory structure:

Visual Leak Detector
    include
        vld.h
        vld_def.h
    lib
        Win32
            vld.lib
        Win64
            vld.lib
    bin
        Win32
            vld_x86.dll
        Win64
            vld_x64.dll

Add the following above your main function:

#ifdef _DEBUG_MEM
#include <vld.h>
#endif

Add the following in your project settings:

_DEBUG_MEM in the preprocessor-definitions
Visual Leak Detector\include in the include-path
Visual Leak Detector\lib\Win<xx> in the library-path
Visual Leak Detector\bin\Win<xx> in the executable-path

Upvotes: 0

0x26res
0x26res

Reputation: 13882

I recommend you use visual leak detector. I should give you all the details you need so you can track the leak and it's easy to install. See here

Upvotes: 1

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