Bug 775993 – validate: Deadlock when doing PAUSE->PLAYING dance on BUFFERING messages while transcoding in filesink

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Bug 775993 - validate: Deadlock when doing PAUSE->PLAYING dance on BUFFERING messages while transcoding in filesink


Summary:	validate: Deadlock when doing PAUSE->PLAYING dance on BUFFERING messages whil...


Status:	RESOLVED OBSOLETE

Product:	GStreamer
Classification:	Platform
Component:	gstreamer (core)
Version:	git master
Hardware:	Other Linux

Importance:	Normal normal
Target Milestone:	git master
Assigned To:	GStreamer Maintainers
QA Contact:	GStreamer Maintainers

URL:
Whiteboard:

Depends on:
Blocks:

Reported:	2016-12-12 16:07 UTC by Thibault Saunier
Modified:	2018-11-03 12:38 UTC

See Also:
GNOME target:	---
GNOME version:	---

Attachments
validate: transcode: No buffering handling when the sink is not synced on the clock (2.06 KB, patch) 2016-12-12 16:07 UTC, Thibault Saunier	committed	Details \| Review

Description Thibault Saunier 2016-12-12 16:07:40 UTC

Created attachment 341827 [details] [review]
validate: transcode: No buffering handling when the sink is not synced on the clock

In gst-validate-transcoder-1.0 we respect do the BUFFERING message and PAUSE the pipeline when starting buffering and go back to PLAYING when this is done, and that even if the sink is not synchronized on the clock.

Validate test: validate.http.transcode.to_vorbis_and_vp8_in_webm.raw_video_mkv

In racy/rare conditions we get a deadlock when `prerolling` going to PAUSED with the following stack trace:

+ Trace 236968

Thread 6 (Thread 0x7fbb541e8700 (LWP 21847))

#0 syscall
#1 g_cond_wait
#2 gst_queue2_wait_free_space
at gstqueue2.c line 1826
#3 gst_queue2_chain_buffer_or_buffer_list
at gstqueue2.c line 2754
#4 gst_queue2_chain
at gstqueue2.c line 2815
#5 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#6 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#7 gst_pad_push_data
at gstpad.c line 4455
#8 gst_pad_push
at gstpad.c line 4574
#9 gst_type_find_element_chain
at gsttypefindelement.c line 896
#10 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#11 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#12 gst_pad_push_data
at gstpad.c line 4455
#13 gst_pad_push
at gstpad.c line 4574
#14 gst_base_src_loop
at gstbasesrc.c line 2855
#15 gst_task_func
at gsttask.c line 334
#16 default_func
at gsttaskpool.c line 68
#17 g_thread_pool_thread_proxy
#18 g_thread_proxy
#19 start_thread
#20 clone

Thread 5 (Thread 0x7fbb537cd700 (LWP 21853))

#0 syscall
#1 g_cond_wait
#2 gst_data_queue_push
at gstdataqueue.c line 520
#3 gst_multi_queue_chain
at gstmultiqueue.c line 2112
#4 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#5 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#6 gst_pad_push_data
at gstpad.c line 4455
#7 gst_pad_push
at gstpad.c line 4574
#8 gst_matroska_demux_parse_blockgroup_or_simpleblock
at matroska-demux.c line 3842
#9 gst_matroska_demux_parse_id
at matroska-demux.c line 4507
#10 gst_matroska_demux_chain
at matroska-demux.c line 4889
#11 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#12 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#13 gst_pad_push_data
at gstpad.c line 4455
#14 gst_pad_push
at gstpad.c line 4574
#15 gst_type_find_element_chain
at gsttypefindelement.c line 896
#16 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#17 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#18 gst_pad_push_data
at gstpad.c line 4455
#19 gst_pad_push
at gstpad.c line 4574
#20 gst_proxy_pad_chain_default
at gstghostpad.c line 126
#21 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#22 gst_pad_push_data
at gstpad.c line 4455
#23 gst_pad_push
at gstpad.c line 4574
#24 gst_queue2_push_one
at gstqueue2.c line 2908
#25 gst_queue2_loop
at gstqueue2.c line 3030
#26 gst_task_func
at gsttask.c line 334
#27 default_func
at gsttaskpool.c line 68
#28 g_thread_pool_thread_proxy
#29 g_thread_proxy
#30 start_thread
#31 clone

Thread 4 (Thread 0x7fbb529ca700 (LWP 21860))

#0 syscall
#1 g_cond_wait
#2 gst_queue_chain_buffer_or_list
at gstqueue.c line 1222
#3 gst_queue_chain
at gstqueue.c line 1320
#4 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#5 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#6 gst_pad_push_data
at gstpad.c line 4455
#7 gst_pad_push
at gstpad.c line 4574
#8 gst_proxy_pad_chain_default
at gstghostpad.c line 126
#9 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#10 gst_pad_push_data
at gstpad.c line 4455
#11 gst_pad_push
at gstpad.c line 4574
#12 gst_proxy_pad_chain_default
at gstghostpad.c line 126
#13 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#14 gst_pad_push_data
at gstpad.c line 4455
#15 gst_pad_push
at gstpad.c line 4574
#16 gst_proxy_pad_chain_default
at gstghostpad.c line 126
#17 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#18 gst_pad_push_data
at gstpad.c line 4455
#19 gst_pad_push
at gstpad.c line 4574
#20 gst_single_queue_push_one
at gstmultiqueue.c line 1611
#21 gst_multi_queue_loop
at gstmultiqueue.c line 1923
#22 gst_task_func
at gsttask.c line 334
#23 default_func
at gsttaskpool.c line 68
#24 g_thread_pool_thread_proxy
#25 g_thread_proxy
#26 start_thread
#27 clone

Thread 3 (Thread 0x7fbb51610700 (LWP 21865))

#0 syscall
#1 g_cond_wait
#2 gst_queue_chain_buffer_or_list
at gstqueue.c line 1222
#3 gst_queue_chain
at gstqueue.c line 1320
#4 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#5 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#6 gst_pad_push_data
at gstpad.c line 4455
#7 gst_pad_push
at gstpad.c line 4574
#8 gst_base_transform_chain
at gstbasetransform.c line 2378
#9 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#10 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#11 gst_pad_push_data
at gstpad.c line 4455
#12 gst_pad_push
at gstpad.c line 4574
#13 gst_stream_combiner_chain
at gststreamcombiner.c line 111
#14 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#15 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#16 gst_pad_push_data
at gstpad.c line 4455
#17 gst_pad_push
at gstpad.c line 4574
#18 gst_video_encoder_finish_frame
at gstvideoencoder.c line 2204
#19 gst_vpx_enc_process
at gstvpxenc.c line 1732
#20 gst_vpx_enc_handle_frame
at gstvpxenc.c line 1921
#21 gst_video_encoder_chain
at gstvideoencoder.c line 1461
#22 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#23 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#24 gst_pad_push_data
at gstpad.c line 4455
#25 gst_pad_push
at gstpad.c line 4574
#26 gst_base_transform_chain
at gstbasetransform.c line 2378
#27 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#28 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#29 gst_pad_push_data
at gstpad.c line 4455
#30 gst_pad_push
at gstpad.c line 4574
#31 gst_video_rate_flush_prev
at gstvideorate.c line 707
#32 gst_video_rate_transform_ip
at gstvideorate.c line 1434
#33 default_generate_output
at gstbasetransform.c line 2184
#34 gst_base_transform_chain
at gstbasetransform.c line 2342
#35 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#36 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#37 gst_pad_push_data
at gstpad.c line 4455
#38 gst_pad_push
at gstpad.c line 4574
#39 gst_base_transform_chain
at gstbasetransform.c line 2378
#40 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#41 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#42 gst_pad_push_data
at gstpad.c line 4455
#43 gst_pad_push
at gstpad.c line 4574
#44 gst_base_transform_chain
at gstbasetransform.c line 2378
#45 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#46 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#47 gst_pad_push_data
at gstpad.c line 4455
#48 gst_pad_push
at gstpad.c line 4574
#49 gst_base_transform_chain
at gstbasetransform.c line 2378
#50 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#51 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#52 gst_pad_push_data
at gstpad.c line 4455
#53 gst_pad_push
at gstpad.c line 4574
#54 gst_stream_splitter_chain
at gststreamsplitter.c line 140
#55 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#56 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#57 gst_pad_push_data
at gstpad.c line 4455
#58 gst_pad_push
at gstpad.c line 4574
#59 gst_queue_push_one
at gstqueue.c line 1359
#60 gst_queue_loop
at gstqueue.c line 1506
#61 gst_task_func
at gsttask.c line 334
#62 default_func
at gsttaskpool.c line 68
#63 g_thread_pool_thread_proxy
#64 g_thread_proxy
#65 start_thread
#66 clone

Thread 2 (Thread 0x7fbb50e0f700 (LWP 21868))

#0 syscall
#1 g_cond_wait
#2 gst_base_sink_wait_preroll
at gstbasesink.c line 2266
#3 gst_base_sink_do_preroll
at gstbasesink.c line 2360
#4 gst_base_sink_do_sync
at gstbasesink.c line 2562
#5 gst_base_sink_chain_unlocked
at gstbasesink.c line 3518
#6 gst_base_sink_chain_main
at gstbasesink.c line 3674
#7 gst_base_sink_chain
at gstbasesink.c line 3703
#8 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#9 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#10 gst_pad_push_data
at gstpad.c line 4455
#11 gst_pad_push
at gstpad.c line 4574
#12 gst_proxy_pad_chain_default
at gstghostpad.c line 126
#13 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#14 gst_pad_push_data
at gstpad.c line 4455
#15 gst_pad_push
at gstpad.c line 4574
#16 gst_ebml_write_flush_cache
at ebml-write.c line 271
#17 gst_ebml_write_header
at ebml-write.c line 940
#18 gst_matroska_mux_start
at matroska-mux.c line 2768
#19 gst_matroska_mux_handle_buffer
at matroska-mux.c line 3794
#20 gst_collect_pads_default_collected
at gstcollectpads.c line 1567
#21 gst_collect_pads_check_collected
at gstcollectpads.c line 1368
#22 gst_collect_pads_chain
at gstcollectpads.c line 2216
#23 gst_validate_pad_monitor_chain_func
at gst-validate-pad-monitor.c line 2121
#24 gst_pad_chain_data_unchecked
at gstpad.c line 4203
#25 gst_pad_push_data
at gstpad.c line 4455
#26 gst_pad_push
at gstpad.c line 4574
#27 gst_queue_push_one
at gstqueue.c line 1359
#28 gst_queue_loop
at gstqueue.c line 1506
#29 gst_task_func
at gsttask.c line 334
#30 default_func
at gsttaskpool.c line 68
#31 g_thread_pool_thread_proxy
#32 g_thread_proxy
#33 start_thread
#34 clone


Going to PAUSED when BUFFERING on a pipeline that is not sync on the clock is useless so I attach here a patch that removes that behaviour in -validate but this case should still work and defenitely not deadlock.

Comment 1 Edward Hervey 2016-12-12 16:19:47 UTC

Review of attachment 341827 [details] [review]:

::: validate/tools/gst-validate-transcoding.c
@@ +478,3 @@
+          g_object_class_find_property (G_OBJECT_GET_CLASS (sink), "sync");
+
+      if (spec) {

We should also not buffer if the sink doesn't have a "sync" property ?

Comment 2 Thibault Saunier 2016-12-12 16:29:46 UTC

(In reply to Edward Hervey from comment #1)
> Review of attachment 341827 [details] [review] [review]:
> 
> ::: validate/tools/gst-validate-transcoding.c
> @@ +478,3 @@
> +          g_object_class_find_property (G_OBJECT_GET_CLASS (sink), "sync");
> +
> +      if (spec) {
> 
> We should also not buffer if the sink doesn't have a "sync" property ?

Well, who knows in that case? :)

Comment 3 Thibault Saunier 2016-12-12 18:15:34 UTC

Comment on attachment 341827 [details] [review]
validate: transcode: No buffering handling when the sink is not synced on the clock

Pushed with suggested change about missing 'sync' property

commit ca85c454829ae8effa31551d56735e5ec2f5a3f6
Author: Thibault Saunier <tsaunier@gnome.org>
Date:   Mon Dec 12 12:27:42 2016 -0300

    validate: transcode: No buffering handling when the sink is not synced on the clock
    
    It makes no sense to pause the pipeline and wait for buffering to be
    done when the pipeline is just processing the data as it comes
    in without synchronizing on the clock.

Comment 4 Sebastian Dröge (slomo) 2016-12-13 09:31:27 UTC

What if a child of the sink bin has the "sync" property? ;)


Do we know why it deadlocks?

Comment 5 GStreamer system administrator 2018-11-03 12:38:32 UTC

-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.

You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/gstreamer/gstreamer/issues/209.