Why this events leak happen?

[Andrey Utkin]

I am still not 100% sure this is a GStreamer bug, although partially
very likely.

Trying to simulate the situation in my app, i made up the following
gst-launch command:

GST_DEBUG=3 G_SLICE=always-malloc valgrind --show-reachable=no
--suppressions=gst.supp gst-launch-1.0 udpsrc uri=udp://225.1.1.1:1234
multicast-iface=lo ! tsdemux name=demux demux.video_0100 ! tee name=t
t.src_0 ! h264parse ! avdec_h264 ! fakesink  t.src_1 ! h264parse !
avdec_h264 ! fakesink   t.src_2 ! h264parse ! avdec_h264 ! fakesink
t.src_3 ! h264parse ! avdec_h264 ! fakesink

Input is just MPEG TS with H.264 stream. (I avoided videotestsrc here
because it produces valgrind false positives by itself. But you should
be able to use it with same result, too). The demuxed result is Tee'ed
4 times. In valgrind log, you see below log.

In my real app, i have same
gst_video_decoder_sink_event_default-related leak, and some others
(gst_event_new_caps, gst_event_new_stream_start,
gst_h264_parse_update_src_caps - for them i cannot produce testcase
and can consider a bug in my app).

gst-everything is from today's git master.

Thanks for any help.

==14260== HEAP SUMMARY:
==14260==     in use at exit: 625,643 bytes in 4,825 blocks
==14260==   total heap usage: 85,654 allocs, 80,829 frees, 24,134,262
bytes allocated
==14260==
==14260== 72 bytes in 3 blocks are definitely lost in loss record 1,798 of 2,576
==14260==    at 0x4C2C5DB: malloc (vg_replace_malloc.c:270)
==14260==    by 0x591221A: g_malloc (gmem.c:159)
==14260==    by 0x592AC50: g_slice_alloc (gslice.c:1003)
==14260==    by 0x5905FB2: g_list_prepend (glist.c:279)
==14260==    by 0x84E2491: gst_video_decoder_sink_event_default
(gstvideodecoder.c:1172)
==14260==    by 0x84E2606: gst_video_decoder_sink_event (gstvideodecoder.c:1204)
==14260==    by 0x4EB4F2B: gst_pad_send_event_unchecked (gstpad.c:5051)
==14260==    by 0x4EB416E: gst_pad_push_event_unchecked (gstpad.c:4747)
==14260==    by 0x4EAF9A4: push_sticky (gstpad.c:3380)
==14260==    by 0x4EA75F4: events_foreach (gstpad.c:533)
==14260==    by 0x4EAFD2E: check_sticky (gstpad.c:3436)
==14260==    by 0x4EB4609: gst_pad_push_event (gstpad.c:4864)
==14260==    by 0x720FD73: gst_base_parse_push_pending_events
(gstbaseparse.c:2025)
==14260==    by 0x7210E78: gst_base_parse_push_frame (gstbaseparse.c:2203)
==14260==    by 0x7210608: gst_base_parse_handle_and_push_frame
(gstbaseparse.c:2131)
==14260==    by 0x72120A8: gst_base_parse_finish_frame (gstbaseparse.c:2453)
==14260==    by 0x909F3D4: gst_h264_parse_handle_frame (gsth264parse.c:959)
==14260==    by 0x720F9A7: gst_base_parse_handle_buffer (gstbaseparse.c:1959)
==14260==    by 0x72144F3: gst_base_parse_chain (gstbaseparse.c:2880)
==14260==    by 0x4EB12A4: gst_pad_chain_data_unchecked (gstpad.c:3773)
==14260==    by 0x4EB1F37: gst_pad_push_data (gstpad.c:4006)
==14260==    by 0x4EB2488: gst_pad_push (gstpad.c:4109)
==14260==    by 0x8E78366: gst_tee_do_push (gsttee.c:586)
==14260==    by 0x8E7859B: gst_tee_handle_data (gsttee.c:658)
==14260==    by 0x8E78920: gst_tee_chain (gsttee.c:730)
==14260==    by 0x4EB12A4: gst_pad_chain_data_unchecked (gstpad.c:3773)
==14260==    by 0x4EB1F37: gst_pad_push_data (gstpad.c:4006)
==14260==    by 0x4EB2488: gst_pad_push (gstpad.c:4109)
==14260==    by 0x7E685CE: gst_ts_demux_push_pending_data (tsdemux.c:1763)
==14260==    by 0x7E68961: gst_ts_demux_handle_packet (tsdemux.c:1802)
==14260==    by 0x7E68A82: gst_ts_demux_push (tsdemux.c:1840)
==14260==    by 0x7E5C940: mpegts_base_chain (mpegtsbase.c:1125)
==14260==    by 0x4EB12A4: gst_pad_chain_data_unchecked (gstpad.c:3773)
==14260==    by 0x4EB1F37: gst_pad_push_data (gstpad.c:4006)
==14260==    by 0x4EB2488: gst_pad_push (gstpad.c:4109)
==14260==    by 0x723704F: gst_base_src_loop (gstbasesrc.c:2785)
==14260==    by 0x4EE6047: gst_task_func (gsttask.c:316)
==14260==    by 0x4EE7142: default_func (gsttaskpool.c:70)
==14260==    by 0x59379BD: g_thread_pool_thread_proxy (gthreadpool.c:309)
==14260==    by 0x59373D2: g_thread_proxy (gthread.c:798)
==14260==    by 0x601BDA5: start_thread (in /lib64/libpthread-2.15.so)
==14260==
==14260== 320 (32 direct, 288 indirect) bytes in 1 blocks are
definitely lost in loss record 2,496 of 2,576
==14260==    at 0x4C2C5DB: malloc (vg_replace_malloc.c:270)
==14260==    by 0x591221A: g_malloc (gmem.c:159)
==14260==    by 0x592AC50: g_slice_alloc (gslice.c:1003)
==14260==    by 0x4ED542F: gst_structure_new_id_empty_with_size
(gststructure.c:147)
==14260==    by 0x4ED551A: gst_structure_new_id_empty (gststructure.c:174)
==14260==    by 0x4ED6FA2: gst_structure_new_id (gststructure.c:757)
==14260==    by 0x4E95658: gst_event_new_segment (gstevent.c:711)
==14260==    by 0x7E6767B: calculate_and_push_newsegment (tsdemux.c:1652)
==14260==    by 0x7E67C4D: gst_ts_demux_push_pending_data (tsdemux.c:1731)
==14260==    by 0x7E68961: gst_ts_demux_handle_packet (tsdemux.c:1802)
==14260==    by 0x7E68A82: gst_ts_demux_push (tsdemux.c:1840)
==14260==    by 0x7E5C940: mpegts_base_chain (mpegtsbase.c:1125)
==14260==    by 0x4EB12A4: gst_pad_chain_data_unchecked (gstpad.c:3773)
==14260==    by 0x4EB1F37: gst_pad_push_data (gstpad.c:4006)
==14260==    by 0x4EB2488: gst_pad_push (gstpad.c:4109)
==14260==    by 0x723704F: gst_base_src_loop (gstbasesrc.c:2785)
==14260==    by 0x4EE6047: gst_task_func (gsttask.c:316)
==14260==    by 0x4EE7142: default_func (gsttaskpool.c:70)
==14260==    by 0x59379BD: g_thread_pool_thread_proxy (gthreadpool.c:309)
==14260==    by 0x59373D2: g_thread_proxy (gthread.c:798)
==14260==    by 0x601BDA5: start_thread (in /lib64/libpthread-2.15.so)
==14260==
==14260== LEAK SUMMARY:
==14260==    definitely lost: 104 bytes in 4 blocks
==14260==    indirectly lost: 288 bytes in 4 blocks
==14260==      possibly lost: 0 bytes in 0 blocks

-- 
Andrey Utkin