[x264-devel] Memory leaks in encoder.c

[Ralf Terdic]

Hi there,

valgrind shows some memory leaks in encoder.c, it looks like some frames are 
not freed. For one encoding thread (see [1]), this is easily fixed:

diff --git a/encoder/encoder.c b/encoder/encoder.c
index 43f9f9f..e86935e 100644
--- a/encoder/encoder.c
+++ b/encoder/encoder.c
@@ -1962,6 +1962,10 @@ void    x264_encoder_close  ( x264_t *h )
     for( i = 0; h->frames.reference[i]; i++ )
         x264_frame_delete( h->frames.reference[i] );
 
+    if (h->param.i_threads == 1) {
+        x264_frame_delete( h->fdec );
+    }
+
     /* rc */
     x264_ratecontrol_delete( h );

See [2] for valgrind results after the patch.

But this doesn't help much with more than one encoding thread. It's quite 
difficult for me to understand what's going on. Each thread seems to have 
four stacks, the relevant ones seem to be thread->frames.unused and 
thread->frames.reference. After the encoding, these stacks contain references 
to some frames. x264_encoder_close deletes those frames that are referenced 
by stacks belonging to the *first* thread, but that's not enough, and I'm 
sure this causes the memory leaks.

Unfortunately, you can't simply delete all frames referenced by all stacks, 
because some frames are referenced to by more than one stack, and I don't see 
how I could easily check whether a frame was freed already, except by doing 
lots of ugly comparisons. Any ideas?

Ralf

[1]
# valgrind --leak-check=full --show-reachable=yes --leak-resolution=high 
x264 -o x264test.mp4 --fps 23.976 --crf 26 --threads 1 raw.yuv 640x480
...
==17829== 511,632 (3,152 direct, 508,480 indirect) bytes in 1 blocks are 
definitely lost in loss record 5 of 14
==17829==    at 0x4021A92: memalign (vg_replace_malloc.c:460)
==17829==    by 0x804EDEB: x264_malloc (common.c:728)
==17829==    by 0x806B143: x264_frame_new (frame.c:28)
==17829==    by 0x806B6AF: x264_frame_pop_unused (frame.c:889)
==17829==    by 0x8054D0B: x264_encoder_open (encoder.c:728)
==17829==    by 0x804B63B: main (x264.c:775)
...
==17829== LEAK SUMMARY:
==17829==    definitely lost: 3,152 bytes in 1 blocks.
==17829==    indirectly lost: 508,480 bytes in 13 blocks.
==17829==      possibly lost: 2,486,294 bytes in 14 blocks.
==17829==    still reachable: 3,496 bytes in 1 blocks.
==17829==         suppressed: 0 bytes in 0 blocks.

[2]
==18883== LEAK SUMMARY:
==18883==    definitely lost: 0 bytes in 0 blocks.
==18883==      possibly lost: 720,918 bytes in 11 blocks.
==18883==    still reachable: 3,496 bytes in 1 blocks.
==18883==         suppressed: 0 bytes in 0 blocks.