libmpv with lua: leaking memory with each new mpv instance

[a10r]

mpv Information

[   0.003][v][cplayer] mpv v0.38.0-559-g22fc2e6a Copyright © 2000-2024 mpv/MPlayer/mplayer2 projects
[   0.004][v][cplayer]  built on Jun 26 2024 12:07:11
[   0.004][v][cplayer] libplacebo version: v7.349.0 (v7.349.0-rc1-3-g1fd3c7b-dirty)
[   0.004][v][cplayer] FFmpeg version: N-116017-ge61fed828
[   0.004][v][cplayer] FFmpeg library versions:
[   0.004][v][cplayer]    libavcodec      61.8.100
[   0.004][v][cplayer]    libavdevice     61.2.100
[   0.004][v][cplayer]    libavfilter     10.2.102
[   0.004][v][cplayer]    libavformat     61.4.100
[   0.004][v][cplayer]    libavutil       59.26.100
[   0.004][v][cplayer]    libswresample   5.2.100
[   0.004][v][cplayer]    libswscale      8.2.100
[   0.004][v][cplayer] 
[   0.004][v][cplayer] Configuration: -Dgpl=false -Ddebug=true -Db_ndebug=true -Doptimization=3 -Db_lto=true -Db_lto_mode=thin -Dcplayer=false -Dlibmpv=true -Dpdf-build=disabled -Dlua=enabled -Djavascript=enabled -Dsdl2=enabled -Dlibarchive=enabled -Dlibbluray=enabled -Ddvdnav=disabled -Duchardet=enabled -Drubberband=disabled -Dlcms2=enabled -Dopenal=disabled -Dspirv-cross=enabled -Dvulkan=enabled -Dvapoursynth=enabled -Degl-angle=enabled -Dc_args=-Wno-error=int-conversion -Dprefix=/__w/mpv-winbuild/mpv-winbuild/mpv-winbuild-cmake/build64/install/x86_64-w64-mingw32 -Dlibdir=/__w/mpv-winbuild/mpv-winbuild/mpv-winbuild-cmake/build64/install/x86_64-w64-mingw32/lib -Ddefault_library=shared -Dprefer_static=True --cross-file=/__w/mpv-winbuild/mpv-winbuild/mpv-winbuild-cmake/build64/meson_cross.txt
[   0.004][v][cplayer] List of enabled features: build-date cplugins cuda-hwaccel cuda-interop d3d-hwaccel d3d11 d3d9-hwaccel debug dos-paths dxgi-debug dxgi-debug-d3d11 egl-angle egl-angle-win32 ffmpeg ffnvcodec gl gl-dxinterop gl-dxinterop-d3d9 gl-win32 glob glob-win32 iconv javascript jpeg lcms2 libarchive libass libavdevice libbluray libplacebo luajit pathcch sdl2 sdl2-audio sdl2-gamepad sdl2-video shaderc spirv-cross uchardet vaapi vaapi-win32 vapoursynth vector vulkan vulkan-interop wasapi win32 win32-desktop win32-threads zimg zimg-st428 zlib

(https://github.com/zhongfly/mpv-winbuild/releases/tag/2024-06-26-22fc2e6)

Other Information

• Windows version: Windows 11 23H2 (10.0.22631.3737)
• Source of mpv: Recent libmpv Windows builds by shinchiro and zhongfly; self-compiled with MSYS2 as described here
• Introduced in version: Possibly between 2020-04-05 and 2020-04-12?

Reproduction Steps

I'm seeing an issue where creating and terminating an mpv instance with libmpv leaks some memory (~1.5 MB per instance) if lua is enabled.

I believe this issue was previously discussed in #9860.

I'm using this test program linked against the libmpv DLL:

int main()
{
    std::cin.ignore(10000, '\n');
    std::cout << "Starting\n";
    for (int i = 0; i < 500; i++)
    {
        auto handle = mpv_create();
        mpv_initialize(handle);
        mpv_terminate_destroy(handle);
    }
    std::cout << "Finished\n";
    std::cin.ignore(10000, '\n');
}

I would expect memory usage to remain constant, but it increases linearly while the loop is running and never goes down again.

I was able to narrow it down to the lua build option: If I disable lua from the mpv build (-Dlua=disabled), the memory leak disappears, and memory use is constant when using the test program.

I was using the builds and scripts by shinchiro and zhongfly initially, then tried compiling a build with MSYS2 as described here and I'm seeing the same behavior with that.

I can confirm this post stating that the shinchiro libmpv build from 2020-04-05 did not leak, but the build from 2020-04-12 did, so it could be that the problem was introduced around that time.

Expected Behavior

No memory leak with lua enabled.

Actual Behavior

Memory leak with lua enabled.

Log File

Added mpv_load_config_file(handle, "log.conf"); after mpv_create(), log.conf contains this:

log-file=mpv-log.txt
msg-level=all=debug
gpu-debug=yes

Log file for one iteration: mpv-log.txt

Sample Files

No response

I carefully read all instruction and confirm that I did the following:

• [X] I tested with the latest mpv version to validate that the issue is not already fixed.
• [X] I provided all required information including system and mpv version.
• [X] I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of --log-file=output.txt.
• [X] I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
• [X] I attached the full, untruncated log file.
• [X] I attached the backtrace in the case of a crash.

[Dudemanguy]

Without bothering to check if there's any leak for me, here are the related looking commits in that timeframe if anyone wants to look into it.

fd3caa264ea0848e7e30db94390063c87e247003 1e780251aebc4103242cf60d9cba6aa2f6424f62 a67bda28409dd893617ef47f6e089fd753d7de78

[wbtcpip2]

i opened several issues on this subject ... the problem is real and you always close without investigations ... it leaks approx 1 MB at each instance

#9860

[Dudemanguy]

Oh so actually I can confirm this happens but it's only with luajit. That would explain why people in the old issue couldn't reproduce it reliably.

[kasper93]

Does it also happen if you compile luajit with -DLUAJIT_USE_SYSMALLOC, they have their own allocator. I don't know the details, but maybe it doesn't release memory right away, and this is what you see.

[Dudemanguy]

maybe it doesn't release memory right away

Did not try messing with luajit yet, but this is almost certainly what is happening. ASAN doesn't report any leaks.

[wbtcpip2]

is this related to our topic? https://github.com/LuaJIT/LuaJIT/issues/1179

[Dudemanguy]

is this related to our topic?

Unfortunately I am using luajit from git master which includes the fix for that issue and the problem still occurs.

Does it also happen if you compile luajit with -DLUAJIT_USE_SYSMALLOC,

~Unless I'm doing it wrong, yeah it still happens with this.~ My bad, wrong compile. It indeed doesn't happen with that flag.

[wbtcpip2]

is it possible to use the flag -DLUAJIT_USE_SYSMALLOC with the official win release of libmpv? do we have to ask it to shinchiro?

[kasper93]

Will be fixed by #14457

[wbtcpip2]

hello, could you please reopen this issue?

#14457 has fixed the memory leak but after this commit there is 1 leak handle at each new mpv instance (that was not present before the #14457 )

@kasper93 could you please check if in your commit there is an handle that is not closed?

[a10r]

Thanks for the quick fix! Can confirm that the leak is gone in the latest zhongfly build.