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Possible memory leak in allegro 5.0.10
Aikei_c
Member #14,871
January 2013
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OK, here is the code I (mostly) took from wiki:

#SelectExpand
1#define CRTDBG_MAP_ALLOC 2#include <stdlib.h> 3#include <crtdbg.h> 4 5#include "allegro5/allegro.h" 6#include "allegro5/allegro_image.h" 7#include "allegro5/allegro_native_dialog.h" 8 9int main(int argc, char **argv) 10{ 11 _CrtSetDbgFlag ( _CRTDBG_ALLOC_MEM_DF |_CRTDBG_LEAK_CHECK_DF ); 12 ALLEGRO_DISPLAY *display = NULL; 13 ALLEGRO_BITMAP *image = NULL; 14 15 if(!al_init()) 16 { 17 al_show_native_message_box(display, "Error", "Error", "Failed to initialize allegro!", 18 NULL, ALLEGRO_MESSAGEBOX_ERROR); 19 return 0; 20 } 21 22 if(!al_init_image_addon()) 23 { 24 al_show_native_message_box(display, "Error", "Error", "Failed to initialize al_init_image_addon!", 25 NULL, ALLEGRO_MESSAGEBOX_ERROR); 26 return 0; 27 } 28 29 display = al_create_display(800,600); 30 31 if(!display) 32 { 33 al_show_native_message_box(display, "Error", "Error", "Failed to initialize display!", 34 NULL, ALLEGRO_MESSAGEBOX_ERROR); 35 return 0; 36 } 37 38 image = al_load_bitmap("image.png"); 39 40 if(!image) 41 { 42 al_show_native_message_box(display, "Error", "Error", "Failed to load image!", 43 NULL, ALLEGRO_MESSAGEBOX_ERROR); 44 al_destroy_display(display); 45 return 0; 46 } 47 48 al_draw_bitmap(image,200,200,0); 49 50 al_flip_display(); 51 al_rest(2); 52 53 al_destroy_display(display); 54 al_destroy_bitmap(image); 55 al_shutdown_image_addon(); 56 al_uninstall_system(); 57 58 return 0; 59}

I also added the _CrtSetDbgFlag ( _CRTDBG_ALLOC_MEM_DF |_CRTDBG_LEAK_CHECK_DF ) line which is a crt function which spots memory leaks and dumps them to output at program termination (http://msdn.microsoft.com/en-us/library/vstudio/x98tx3cf.aspx)
When the program terminates, I get the following output:

Detected memory leaks!

Dumping objects -> {564} normal block at 0x007CB008, 65536 bytes long. Data: <+Da +Da +Da +Da > 2B 44 61 FF 2B 44 61 FF 2B 44 61 FF 2B 44 61 FF Object dump complete.

I then set a breakpoint at block 564 allocation, and this block is allocated when allegro bitmap is loaded, specifically, in _al_d3d_create_bitmap(), you can see attachment to get the idea where it is.

Memory for d3d bitmap is probably not deallocated at program termination, despite explicit call to allegro_destroy_bitmap().

Or it may be false positive.

Arthur Kalliokoski
Second in Command
February 2005
avatar

65536 bytes! Zomg!

They all watch too much MSNBC... they get ideas.

Aikei_c
Member #14,871
January 2013
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Actually, there must be an error in this tutorial: http://wiki.allegro.cc/index.php?title=Basic_tutorial_on_loading_and_showing_images
When I free the image BEFORE freeing the display (which uses this image, probably), no memory leaks are detected.
I must say, though, that it is not specified anywhere, although seems natural. However, this tutorial really confused me.

P.S.: Can I edit the order of these calls in wiki?

Vanneto
Member #8,643
May 2007

Of course you can. Any contribution to the wiki is welcome and appreciated.

In capitalist America bank robs you.

Matthew Leverton
Supreme Loser
January 1999
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When you destroy the display first, the bitmap is converted to a memory bitmap. So perhaps that process is leaking some memory.

beoran
Member #12,636
March 2011

It shouldn't though. If no one else takes this, I'll look into it after my holiday.

Thomas Fjellstrom
Member #476
June 2000
avatar

Holidays are the perfect time to work on side projects.

--
Thomas Fjellstrom - [website] - [email] - [Allegro Wiki] - [Allegro TODO]
"If you can't think of a better solution, don't try to make a better solution." -- weapon_S
"The less evidence we have for what we believe is certain, the more violently we defend beliefs against those who don't agree" -- https://twitter.com/neiltyson/status/592870205409353730

beoran
Member #12,636
March 2011

Unfortunately, not so if they are family holidays. Ah well, that's what it's like to be a father. :)

Thomas Fjellstrom
Member #476
June 2000
avatar

Nah, nothing says you actually have to spend all of your time on a holiday catering to your family ;)

--
Thomas Fjellstrom - [website] - [email] - [Allegro Wiki] - [Allegro TODO]
"If you can't think of a better solution, don't try to make a better solution." -- weapon_S
"The less evidence we have for what we believe is certain, the more violently we defend beliefs against those who don't agree" -- https://twitter.com/neiltyson/status/592870205409353730

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