Bug 253446 – REGRESSION(2.39.90): [GTK] Rendering errors on cnn.com

• Component: WebKitGTK
• Status: NEW

[Michael Catanzaro]

Created attachment 465317 [details]
Screenshot

It looks like tiles are getting jumbled around when rendering cnn.com (see attachment).

Unfortunately I do not have a reliable reproducer, but I've seen it a few times recently and I believe this never happened prior to 2.39.90.

[Michael Catanzaro]

Created attachment 465326 [details]
Another screenshot

Another screenshot, this time with only the Mapbox widget broken

[Michael Catanzaro]

This appears to be fixed on main, and only broken in the 2.40 stable branch.

[Michael Catanzaro]

(In reply to Michael Catanzaro from comment #2)
> This appears to be fixed on main, and only broken in the 2.40 stable branch.

Actually I'm not confident about this. It's much harder to reproduce in my development MiniBrowser than it is in Ephy Tech Preview so that might just have been luck.

[Michael Catanzaro]

Ah, I've found the bug appears to be related to window size. With larger window size, I can reproduce with MiniBrowser using 2.40.0. Can't reproduce using main.

[Adrian Perez]

I cannot reproduce this on a 2.40.x build from the tip of the release
branch, but this is using GTK3. I'm making a GTK4 build to check, but
there is some little chance that it's fixed by one of the patches that
have been backported 🤔️

[Adrian Perez]

(In reply to Adrian Perez from comment #5)
> I cannot reproduce this on a 2.40.x build from the tip of the release
> branch, but this is using GTK3. I'm making a GTK4 build to check, but
> there is some little chance that it's fixed by one of the patches that
> have been backported 🤔️

I cannot reproduce it either with a GTK4 build of the current tip of
the 2.40.x release branch (commit 6dcdac4b3d5a). I've tried changing the
MiniBrowser window size a few times, but even maximized on a 1920x1080
monitor (no HiDPI, @1x scale) there are no glitches.

Michael, what size exactly is the window when you see glitches? Or,
alternatively, could you check a build with the commit mentioned above?

[Michael Catanzaro]

Created attachment 465646 [details]
Another screenshot

Here is a screenshot taken with webkitglib/2.40 (commit 4524c8a9e1d4ae627ea2279ffed0ff05f806adf0) showing the bug. Definitely not fixed on the stable branch.

[Michael Catanzaro]

Anyway, it's impossible to be certain because the bug does not occur reliably, but I'm once again convinced myself that this is fixed in trunk. I will attempt to bisect this, although there's a high chance of failure here as there's a lot of luck involved.

[Michael Catanzaro]

(In reply to Adrian Perez from comment #6)
> Michael, what size exactly is the window when you see glitches?

I dunno. MiniBrowser does not remember its window size. I've just been resizing it each time I try to reproduce this bug, so the size will be different each time.

[Adrian Perez]

(In reply to Michael Catanzaro from comment #9)
> (In reply to Adrian Perez from comment #6)
> > Michael, what size exactly is the window when you see glitches?
> 
> I dunno. MiniBrowser does not remember its window size. I've just been
> resizing it each time I try to reproduce this bug, so the size will be
> different each time.

Okay, so we are doing basically the same, and from your screenshot it
doesn't look like you have a HiDPI screen either. Maybe it's one of
these issues that, by chance, one person has more ease reproducing than
others—too bad we don't have a good reproducer :\

[Michael Catanzaro]

Created attachment 465681 [details]
Yet another screenshot

Oooh, I found another affected website:

https://www.riverfronttimes.com/news/st-louis-to-extend-controversial-parking-management-contract-39741060

(still intend to attempt to bisect this)

[Michael Catanzaro]

(In reply to Michael Catanzaro from comment #11)
> (still intend to attempt to bisect this)

I'm not going to succeed. It's too hard to reproduce.

[Michael Catanzaro]

OK, I hit this today on reddit.com using 2.41.1, so I was wrong: it's not a stable branch bug after all. I still have not been able to reproduce on cnn.com but no question it's the same bug.

[Michael Catanzaro]

Something changed and now this bug is happening drastically more often with 2.41.2 on reddit.com. It's so severe that I'll probably downgrade the GNOME runtime back to 2.41.1, which was also affected but much less often.

[Michael Catanzaro]

On the other hand, I suspect I will be more productive if I cannot use reddit. Hmmm. ;)

[Michael Catanzaro]

src.fedoraproject.org is now broken as well.

[Michael Catanzaro]

OK so strangely enough, the rendering errors on reddit.com are occurring more commonly due to bug #255488. I know it seems weird but they are definitely related. To reduce bugzilla confusion, let's handle the 2.41.2 regressions in bug #255488 and keep this bug focused on the original regression from 2.39.90.

[Michael Catanzaro]

OK, with bug #255488 resolved as something different: I haven't seen the original problem here with cnn.com since upgrading to 2.41.2. I think it's probably fixed. Shame we don't know when it got fixed to do a backport for 2.40.