Linux resource leak

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Jonathan Campbell

  • Posts: 6
  • Joined: Fri Sep 05, 2014 11:51 pm

Linux resource leak

PostSat Feb 28, 2015 3:45 am

I have a Decklink Duo and I just updated our Castus unit to driver 10.3.7. Our code uses the C++ interfaces under Linux. We're using (what I understand) is the latest version of the SDK 10.3.1. Linux kernel 3.14.15 on x86_64.

I'm noticing that no matter what I release, the SDK seems to leave file handles and memory maps behind. What it opens and maps on capture or playback it never frees when I release all the objects.

This is a serious issue to us because it means that about 300MB of application resources is leaked every time our code opens or reopens the device. Leaving the device open at all times is not an option, the code in question is for a video capture source that is opened only when the schedule or user requests video, else, it closes it. If we allow the leak to excess, it can consume all 4GB of RAM in the system and then trigger the Linux OOM killer.

Our code is using the v9.9 interface because many of our systems out in the field have not yet been upgraded and our clients need to stay on the air. The leak seems to happen as early as when our code uses QueryInterface to obtain the IDeckLinkConfiguration of the input.

Interfaces used:

Code: Select all
# if BLACKMAGIC_DECKLINK_API_VERSION >= 0x0a010400
# include <isp-utils-v4/media-item/DeckLinkAPI_v9_9.h>
#  define IDeckLinkOutput               IDeckLinkOutput_v9_9
#  define IID_IDeckLinkOutput           IID_IDeckLinkOutput_v9_9
# endif
#endif

IDeckLinkDisplayMode*                           decklink_displaymode_changed = NULL;
IDeckLinkDisplayMode*                           decklink_displaymode = NULL;
IDeckLinkConfiguration*                         decklink_cfg = NULL;
IDeckLinkInput*                                 decklink_in = NULL;
IDeckLinkIterator*                              decklink_i = NULL;
IDeckLink*                                      decklink = NULL;


Closing:

Code: Select all
        if (decklink_displaymode_changed != NULL) {
                decklink_displaymode_changed->Release();
                decklink_displaymode_changed=NULL;
        }
        if (decklink_displaymode != NULL) {
                decklink_displaymode->Release();
                decklink_displaymode=NULL;
        }
        if (decklink_cfg != NULL) {
                decklink_cfg->Release();
                decklink_cfg=NULL;
        }
        if (decklink_in != NULL) {
                decklink_in->StopStreams();
                decklink_in->DisableVideoInput();
                decklink_in->DisableAudioInput();
                decklink_in->Release();
                decklink_in=NULL;
        }
        if (decklink != NULL) {
                decklink->Release();
                decklink=NULL;
        }
        if (decklink_i != NULL) {
                decklink_i->Release();
                decklink_i=NULL;
        }


Until recently that freed all resources as normal, until 10.3.5 and 10.3.7, where the memory map and file handles are left behind (plainly visible in /proc/<pid>/fd and /proc/<pid>/maps).

Can you please address this resource leak?
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Jonathan Campbell

  • Posts: 6
  • Joined: Fri Sep 05, 2014 11:51 pm

Re: Linux resource leak

PostTue Mar 10, 2015 10:10 pm

I can confirm that the leak remains even in the latest version of the SDK, but we can eliminate the leak if we comment out the following in our code that requests the IDecklinkConfiguration interface:

Code: Select all
        if (decklink_out->QueryInterface(IID_IDeckLinkConfiguration, (void**)(&decklink_cfg)) != S_OK) {
                fprintf(stderr,"Failed to get decklink cfg\n");
                assert(decklink_cfg == NULL);
        }


So the leak seems to involve somehow the decklink configuration interface. Our code uses this to allow the user to control output enables and audio levels.

EDIT: I want to clarify our code is very careful about management and it makes sure to call decklink_cfg->Release() when it's done. Despite releasing the interface, the leak still happens, unless my code never requests the interface in the first place.
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Marc Cymontkowski

  • Posts: 1
  • Joined: Mon Mar 16, 2015 9:44 am

Re: Linux resource leak

PostMon Mar 16, 2015 9:48 am

We are seeing the same issue on our systems with DeckLink Duo and Quad cards. Memory keeps increasing between 100 and 300 MB on every configuration cycle, in our case on Stop/Restart Capture combinations.

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