Bug 201726 – REGRESSION(r249205): [GStreamer][MSE] playbin3 assertion during YouTube front-page load: combiner_control_pad: assertion failed: (combine->sinkpad != NULL)

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Charlie Turner]

Created attachment 378656 [details]
backtrace

Backtrace available in attachment area. This is a racey failure unfortunately, but I see it quite often after the MSE refactoring.

[Charlie Turner]

Created attachment 378657 [details]
GStreamer debug logging

Attach a run.log with lots of GStreamer logging

[Philippe Normand]

*** Bug 201652 has been marked as a duplicate of this bug. ***

[Michael Catanzaro]

IMO this is critical and we should revert the MSE rewrite if it can't be fixed ASAP.

[Alicia Boya García]

(In reply to Michael Catanzaro from comment #3)
> IMO this is critical and we should revert the MSE rewrite if it can't be
> fixed ASAP.

I know. I'm working on this among other playbin3-related bugs. I don't mind if you revert the WebKitMediaSrc rework commit on releases, I already commented back in the day that it was too soon to release it in production.

[Michael Catanzaro]

OK, I suggest we can leave it in trunk (it's OK if trunk is crashy for a couple weeks while you work on a fix), but revert for 2.26 branch (where it's not OK). Then you can have another six months to focus on making the rewrite nice and stable in trunk.

[Michael Catanzaro]

(In reply to Michael Catanzaro from comment #5)
> OK, I suggest we can leave it in trunk (it's OK if trunk is crashy for a
> couple weeks while you work on a fix)

Well this might have been a bad suggestion; this crash is too much for Tech Preview too. Alicia, how inconvenient would it be for you if I revert this on trunk? Can you have it solved before 2.27.1 (three weeks)? I don't want this crashing in 2.27.1.

[Michael Catanzaro]

Hm, I thought there was only one crash here, but trying to play a couple youtube.com videos 10x in a row just now, I got 10 crashes before I gave up. They were actually two different crashes, not this one. I've definitely seen this one many times in the past several days, but it's not what I'm hitting today. Reported bug #202078 and bug #202079.

[Michael Catanzaro]

So I'm not sure why 2.27.2 was released before addressing these issues. The goal of Tech Preview is to be as new as possible while still avoiding known critical regressions, so I'll continue to hold Tech Preview to 2.26.

[Carlos Garcia Campos]

(In reply to Michael Catanzaro from comment #8)
> So I'm not sure why 2.27.2 was released before addressing these issues. The
> goal of Tech Preview is to be as new as possible while still avoiding known
> critical regressions, so I'll continue to hold Tech Preview to 2.26.

The playbin3 support has been removed in 2.27.2. See bug #203078

[Michael Catanzaro]

OK then, I'll try adding it to GNOME runtime.

So: can't this bug be closed now, or does Alicia want it open as a reminder to fix before relanding? What about bug #202078 and bug #202079?

[Alicia Boya García]

It can be closed. The cause of the bug is playbin3 gets confused when several stream-collections are posted in quick succession; but for this and other reasons the next version of the WebKitMediaSrc patch will defer exposing any tracks until all SourceBuffer have received an initialization segment, emitting a single streams-collection message, which shouldn't cause this bug again.

I've replied to the other mentioned bugs too.