Why sdl is reported memory leak by valgrind

SDL Development
1

hello guys:

sdl-config --version: 1.2.13
valgrind --version : valgrind-3.2.3

this is a simple test about sdl (sdltest.c):

#include <SDL/SDL.h>

int main(int argc, char* argv[])
{
SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_AUDIO);
SDL_Quit();
}

then i compiled sdltest.c:
gcc -g -o sdltest sdltest.c -lSDL

next, i run it with valgrind:

valgrind --tool=memcheck --leak-check=full --show-reachable=yes
–error-limit=no ./sdltest

then valgrind report some memory leak error:

==19611== 16 bytes in 2 blocks are definitely lost in loss record 9 of 55
==19611== at 0x4005525: malloc (vg_replace_malloc.c:149)
==19611== by 0xA9F882: (within /usr/lib/libX11.so.6.2.0)
==19611== by 0xA9E0D6: (within /usr/lib/libX11.so.6.2.0)
==19611== by 0xA9F063: _XimSetICValueData (in /usr/lib/libX11.so.6.2.0)
==19611== by 0xAA50D0: _XimLocalCreateIC (in /usr/lib/libX11.so.6.2.0)
==19611== by 0xA8CD7B: XCreateIC (in /usr/lib/libX11.so.6.2.0)
==19611== by 0x619E740: create_aux_windows (SDL_x11video.c:515)
==19611== by 0x619F924: X11_VideoInit (SDL_x11video.c:682)
==19611== by 0x618C5AD: SDL_VideoInit (SDL_video.c:240)
==19611== by 0x615F390: SDL_InitSubSystem (SDL.c:70)
==19611== by 0x615F3D6: SDL_Init (SDL.c:162)
==19611== by 0x80484E0: main (sdltest.c:5)

==19611== 224 (16 direct, 208 indirect) bytes in 2 blocks are definitely
lost in loss record 21 of 55
==19611== at 0x4005622: realloc (vg_replace_malloc.c:306)
==19611== by 0xA92B83: (within /usr/lib/libX11.so.6.2.0)
==19611== by 0xA9371B: (within /usr/lib/libX11.so.6.2.0)
==19611== by 0xA95677: _XlcCreateLC (in /usr/lib/libX11.so.6.2.0)
==19611== by 0xAB3AFA: _XlcDefaultLoader (in /usr/lib/libX11.so.6.2.0)
==19611== by 0xA9BFD2: _XOpenLC (in /usr/lib/libX11.so.6.2.0)
==19611== by 0xA9C112: _XlcCurrentLC (in /usr/lib/libX11.so.6.2.0)
==19611== by 0xA9C5C0: XSetLocaleModifiers (in /usr/lib/libX11.so.6.2.0)
==19611== by 0x6194EBD: XSetLocaleModifiers (SDL_x11sym.h:149)
==19611== by 0x619E8E9: create_aux_windows (SDL_x11video.c:468)
==19611== by 0x619F924: X11_VideoInit (SDL_x11video.c:682)
==19611== by 0x618C5AD: SDL_VideoInit (SDL_video.c:240)

now this report made by valgrind is true or false. i have read the
corresponding source code in SDL, maybe there exist some question
that maybe cause memory leak?

so i want to know there is or not some resource allocated by SDL_Init is not
release by SDL_Quit?

thanks.

2

then valgrind report some memory leak error:

It’s a leak in Xlib, even if we properly clean up the subsystem that
allocated the memory.

–ryan.

3

thanks for your response. maybe this leak exist in many versions of Xlib,
why it hasn’t been corrected.

2008/5/19, Ryan C. Gordon :>

then valgrind report some memory leak error:

It’s a leak in Xlib, even if we properly clean up the subsystem that
allocated the memory.

–ryan.

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SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org

4

hi,

Maybe a bug hasn’t been reported?

http://bugs.xfree86.org/
https://bugs.freedesktop.org/On Tue, May 20, 2008 at 11:37 AM, Tao Yu wrote:

thanks for your response. maybe this leak exist in many versions of Xlib,
why it hasn’t been corrected.

2008/5/19, Ryan C. Gordon :

then valgrind report some memory leak error:

It’s a leak in Xlib, even if we properly clean up the subsystem that
allocated the memory.

–ryan.

5

Not sure about this instance, but if it’s in exit/cleanup code, then the
resources are auto-reclaimed by OS, so people tend to be lazy with it…

Also, some leaks, aren’t leaks - see the Valgrind documentation.
Basically, Valgrind isn’t perfect and may sometimes incorrectly report
leaks due to the complexity of the software.

This isn’t a cop-out, it’s just a matter-of-fact. Valgrind provides
facilities to suppress these errors.

Incidentally, the total memory lost is 240 bytes, so it’s probably a
one-of allocation that isn’t freed. If that’s the most your program ever
leaks, I wouldn’t worry about it (as it’s re-claimed by the OS anyway…)

If it were 1MB or more, then it would more likely be a repeat-allocate
without free, which is serious (as this will eventually cause heap
exhaustion), as it could lead to your program failing.

Eddy

Tao Yu wrote:> thanks for your response. maybe this leak exist in many versions of

Xlib, why it hasn’t been corrected.

2008/5/19, Ryan C. Gordon <icculus at icculus.org
<mailto:icculus at icculus.org>>:

    then valgrind report some memory leak error:


It's a leak in Xlib, even if we properly clean up the subsystem that
allocated the memory.

--ryan.


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