c++ - soy - ¿Por qué valgrind dice que el programa SDL básico está perdiendo memoria?

perdida de memoria temporal

Question

Aquí está el programa SDL:

#include <SDL/SDL.h>

int main(int argc, char** argv){


  SDL_Init(SDL_INIT_VIDEO);
  SDL_Surface* screen = SDL_SetVideoMode(640, 480, 16, SDL_HWSURFACE);
  SDL_Quit();
  return 0;

}

Compilado con el comando:

g++ -o test test.cpp -lSDL

Y aquí está la salida de valgrind:

christian@christian-laptop:~/cpp/tetris$ valgrind --leak-check=full ./test
==3271== Memcheck, a memory error detector
==3271== Copyright (C) 2002-2009, and GNU GPL''d, by Julian Seward et al.
==3271== Using Valgrind-3.5.0-Debian and LibVEX; rerun with -h for copyright info
==3271== Command: ./test
==3271== 
==3271== 
==3271== HEAP SUMMARY:
==3271==     in use at exit: 91,097 bytes in 1,258 blocks
==3271==   total heap usage: 14,250 allocs, 12,992 frees, 2,615,177 bytes allocated
==3271== 
==3271== 10 bytes in 2 blocks are definitely lost in loss record 8 of 134
==3271==    at 0x4024C1C: malloc (vg_replace_malloc.c:195)
==3271==    by 0x4946F04: ??? (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x4945DA1: _XimEncodeLocalICAttr (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x4947195: _XimSetICValueData (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x493FDF1: _XimLocalCreateIC (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x4922478: XCreateIC (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x407AA64: ??? (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x407BCBB: ??? (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x4069C2A: SDL_VideoInit (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x403F9D3: SDL_InitSubSystem (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x403FA36: SDL_Init (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x8048658: main (in /home/christian/cpp/tetris/test)
==3271== 
==3271== 12 bytes in 1 blocks are definitely lost in loss record 12 of 134
==3271==    at 0x4024C1C: malloc (vg_replace_malloc.c:195)
==3271==    by 0x4A3DA8D: ???
==3271==    by 0x4A3D48C: ???
==3271==    by 0x4A3D5A4: ???
==3271==    by 0x4A3DD26: ???
==3271==    by 0x4A38BC5: ???
==3271==    by 0x4A38FCD: ???
==3271==    by 0x40717DD: ??? (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x407BDCA: ??? (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x4069C2A: SDL_VideoInit (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x403F9D3: SDL_InitSubSystem (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x403FA36: SDL_Init (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271== 
==3271== 112 (8 direct, 104 indirect) bytes in 1 blocks are definitely lost in loss record 102 of 134
==3271==    at 0x4024D12: realloc (vg_replace_malloc.c:476)
==3271==    by 0x492847E: ??? (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x492976D: ??? (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x492AA41: ??? (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x492B1A4: _XlcCreateLC (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x494B4FA: _XlcDefaultLoader (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x4933153: _XOpenLC (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x49332C2: _XlcCurrentLC (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x4933761: XSetLocaleModifiers (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x407161D: ??? (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x407AD8F: ??? (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271==    by 0x407BCBB: ??? (in /usr/lib/libSDL-1.2.so.0.11.2)
==3271== 
==3271== 112 (8 direct, 104 indirect) bytes in 1 blocks are definitely lost in loss record 103 of 134
==3271==    at 0x4024D12: realloc (vg_replace_malloc.c:476)
==3271==    by 0x492847E: ??? (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x492976D: ??? (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x492AA41: ??? (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x492B1A4: _XlcCreateLC (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x494B4FA: _XlcDefaultLoader (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x4933153: _XOpenLC (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x493327D: _XrmInitParseInfo (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x4918F20: ??? (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x491AF37: XrmGetStringDatabase (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x48F8459: ??? (in /usr/lib/libX11.so.6.2.0)
==3271==    by 0x48F864E: XGetDefault (in /usr/lib/libX11.so.6.2.0)
==3271== 
==3271== LEAK SUMMARY:
==3271==    definitely lost: 38 bytes in 5 blocks
==3271==    indirectly lost: 208 bytes in 8 blocks
==3271==      possibly lost: 0 bytes in 0 blocks
==3271==    still reachable: 90,851 bytes in 1,245 blocks
==3271==         suppressed: 0 bytes in 0 blocks
==3271== Reachable blocks (those to which a pointer was found) are not shown.
==3271== To see them, rerun with: --leak-check=full --show-reachable=yes
==3271== 
==3271== For counts of detected and suppressed errors, rerun with: -v
==3271== ERROR SUMMARY: 4 errors from 4 contexts (suppressed: 93 from 14)

¿Por qué este programa SDL básico pierde memoria?

Answer 1

Cada SDL_Surface que cargue debe liberarse antes de la llamada de SDL_Quit ().

Para hacer esto, simplemente use SDL_FreeSurface (surfaceName) para liberar la superficie que asignó en la memoria.

Answer 2

Incluso para el programa básico "hola mundo" de OpenGL sin el SDL completo, Valgrind me da advertencias similares en las bibliotecas de OpenGL. Es peculiar, pero lo he asumido.

• Los implementadores de la biblioteca saben lo que están haciendo (probablemente preasignando algunos búferes estáticos pequeños que nunca se molestan en liberar),
• Incluso si no lo hacen, es una fuga de una sola vez que será reclamada por el sistema operativo cuando el programa termina,

y no he perdido mucho sueño por eso.

Answer 3

Los Singletons son casi siempre una "fuga" con implementaciones estándar. Sin embargo, eso suele ser correcto, ya que normalmente no es como si quisieras descargar tu capacidad para hacer cosas como imprimir en la consola.

Answer 4

SDL definitivamente tiene un problema de pérdida de memoria con SDL_TLSCleanup y SDL_TLSData .

De hecho, nunca se llama a SDL_TLSCleanup para el hilo principal .