Mutex deadlock using gstcefsrc

[Steve McFarlin]

Issue was programmer error, and a little bit of not RTFM. I was setting
pipeline states in gst callbacks.

On Thu, Jan 19, 2023 at 5:18 PM Steve McFarlin <steve.mcfarlin at hopin.to>
wrote:

> Hello All -
>
> I have code equivalent of this gst-launch pipeline
>
> gst-launch-1.0 -e \
>     cefsrc url="https://www.youtube.com/watch?v=_3EuiU1qdpE" ! \
>     video/x-raw, width=1920, height=1080, framerate=30/1 ! \
>     cefdemux name=demux ! queue ! videoconvert ! \
>     queue max-size-bytes=0 max-size-buffers=0 max-size-time=3000000000
> ! x264enc ! queue ! \
>     mp4mux name=muxer ! filesink location='test.mp4' \
>     audiotestsrc do-timestamp=true is-live=true  volume=0.0 !
> audiomixer name=mix ! \
>     queue max-size-bytes=0 max-size-buffers=0 max-size-time=3000000000
> ! audioconvert ! \
>     audiorate ! audioresample ! avenc_aac bitrate=128000 ! queue ! muxer. \
>     demux. ! queue ! mix.
>
> If I follow this state path:
>
> NULL -> .. -> Paused -> Playing -> send_event(EOS)
>
>  I will enter into a deadlock on the following mutex
>
> **_lldb_unnamed_symbol3461 (@_**lldb*unnamed_symbol3461:19)
> pthread_mutex_lock (@pthread_mutex_lock:106)
> \*\*\_lldb_unnamed_symbol1391 (@***lldb_unnamed_symbol1391:358)
> gst_element_send_event (@gst_element_send_event:38)
> **_lldb_unnamed_symbol3063 (@_\*\*lldb_unnamed_symbol3063:104)
> gst_element_send_event (@gst_element_send_event:38)
> <O as gstreamer::element::ElementExtManual>::send_event
> (cargo/registry/src/github.com-1ecc6299db9ec823/gstreamer-0.19.5/src/
> element.rs:339)
> rendition::recorder::Recorder::stop (/rendition-rs/src/recorder.rs:229)
> rendition::stop::{{closure}} (/rendition-rs/src/bin/rendition.rs:267)
>
> Note that simply going from Null to Paused, and then sending EOS will
> result in the same deadlock. Any transition into and out
> of Paused will deadlock.
>
> What is interesting about this deadlock is it only occurs for me if
> there is a media player
> on the webpage (YouTube, MP4, etc). WebRTC AV does not cause this
> issue. Nothing immediately stands out in a debugger while searching
> through the other threads.
> Can someone suggest where I might look? I'll also try the default
> Spotify CEF build
> to see if that makes a difference. I am usinga custom CEF build with
> chromium 106.0.5249.119.
>
> In my code I am using the following calls to create this deadlock:
>
> pipeline.set_state(gst::State::Paused)
> ...
> pipeline.set_state(gst::State::Playing)
> ...
> pipeline.send_event(gst::event::Eos::new()); // Deadlock here.
>
>
> Thanks,
> Steve
>


-- 
[image: Logo] *Steve McFarlin*
Sr. Staff Engineer


www.hopin.com
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