Hi, On Tue, Apr 4, 2017 at 10:07 AM, Michael Niedermayer <mich...@niedermayer.cc > wrote:
> On Tue, Apr 04, 2017 at 09:09:36AM -0400, Ronald S. Bultje wrote: > > This fixes the following tsan warnings when running fate-dnxhr-parse: > > > > WARNING: ThreadSanitizer: data race (pid=29917) > > Write of size 8 at 0x0000025b12d8 by thread T2 (mutexes: write M1543): > > #0 ff_idctdsp_init src/libavcodec/idctdsp.c:313 > (ffmpeg+0x00000044b68e) > > [..] > > Previous write of size 8 at 0x0000025b12d8 by thread T1 (mutexes: > write M1541): > > #0 ff_idctdsp_init src/libavcodec/idctdsp.c:313 > (ffmpeg+0x00000044b68e) > > --- > > libavcodec/idctdsp.c | 8 ++++---- > > libavcodec/idctdsp.h | 17 +++++++++++++++-- > > 2 files changed, 19 insertions(+), 6 deletions(-) > > does this have any performance effect and why do 2 threads write into > the same variable ? > It seems rather suspicious that 2 diferent threads write into the same > pointer In dnxhd, the initial context is uninitialized and is initialized at runtime during header parsing (or when bpp changes). So each thread calls idctdsp_init() once, each of which writes into the same global variable exactly once. This patch is a total hack, I openly admit that, I'm just exploring the bugs and am happy to discuss alternate designs. Some people have expressed the wish to get rid of the global function pointers which is probably a good longer-term goal... Ronald _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
