1461688 - Firefox freezes while scrolling through long webpages with Accessibility inspection enabled

Status: NEW

(DevTools :: Accessibility Tools, defect, P3)

Description

[Emil Ghitta, QA [:emilghitta]]

Attachment: Aceessibility.gif

[Affected versions]:
Firefox 62.0a1 (BuildId:20180515100038).
Firefox 61.0b4 (BuildId:20180510160705).
	
[Affected platforms]:
Windows 10 64bit.
macOS 10.13.3.
Ubuntu 16.04 64bit.

[Steps to reproduce]:
1.Launch Firefox.
2.Access the https://www.youtube.com webpage.
3.Enable the Accessibility features.
4.Click the "Pick accessible object from the page" button.
5.Hover over webpage elements while scrolling through the webpage. 

[Expected result]:
A transparent overlay is successfully displayed over the hovered elements and no performance issues are encountered.

[Actual result]:
Firefox freezes while scrolling through the webpage elements and the only way to restart the browser is to kill the process.

After doing this several times, some IPCError-browser | ShutDownKill crash reports were generated:
- 7fe3ee7a-6bf4-44cc-9e0c-ad7180180515
- 60e9138a-cba4-4716-b145-33f460180515

[Regression range]:
I don't think that this is a regression.

[Additional information]:
For further information regarding this issue please observe the attached screencast.
I also generate a dump file: https://drive.google.com/open?id=1MRGpN58jz7b5vn5BCTfgxU8OJEq96st1
I managed to reproduce this issue on websites like: YouTube or Imgur.

Comment 1

[Yura Zenevich [:yzen] (please use "needinfo")]

Hi Emil, I noticed similar lag on YouTube and the HTLM inspector, is that something you observe on your side?

Comment 2

[Emil Ghitta, QA [:emilghitta]]

Hi Yura, 

Unfortunately, I can't reproduce this lag with the html inspector.

Comment 3

[Yura Zenevich [:yzen] (please use "needinfo")]

Thanks, 

FYI we have this message when starting the tool:

"Accessibility features are deactivated by default because they negatively impact performance. Consider turning off accessibility features before using other Developer Tools panels."

It is still worth further investigation though, in case we can improve certain things. Best results I've seen were related to not on-the-spot highlighting (Chrome does that) so it could be one option in the future.

Comment 4

[James Teh [:Jamie]]

(In reply to Yura Zenevich [:yzen] from comment #1)
> Hi Emil, I noticed similar lag on YouTube and the HTLM inspector, is that
> something you observe on your side?

Yura, did you have accessibility enabled (even without the a11y inspector) when testing? Wondering whether this is a general a11y issue. Certainly, we have bug 1395536 concerning a11y perf with Youtube.

Comment 5

[Yura Zenevich [:yzen] (please use "needinfo")]

(In reply to James Teh [:Jamie] from comment #4)
> (In reply to Yura Zenevich [:yzen] from comment #1)
> > Hi Emil, I noticed similar lag on YouTube and the HTLM inspector, is that
> > something you observe on your side?
> 
> Yura, did you have accessibility enabled (even without the a11y inspector)
> when testing? Wondering whether this is a general a11y issue. Certainly, we
> have bug 1395536 concerning a11y perf with Youtube.

I don't believe I had, I don't think I tried it on Windows either. I will look at this bug this week though.

Comment 6

[Jan Honza Odvarko [:Honza] (always need-info? me)]

Yura, the severity is set to "Major" for this bug , but no activity for 3 years.
Is this still reproducible? Perhaps it's been fixed?

Comment 7

[BugBot [:suhaib / :marco]]

Redirect a needinfo that is pending on an inactive user to the triage owner.
:Jamie, since the bug has high severity and recent activity, could you have a look please?

For more information, please visit auto_nag documentation.

Comment 8

[BugBot [:suhaib / :marco]]

In the process of migrating remaining bugs to the new severity system, the severity for this bug cannot be automatically determined. Please retriage this bug using the new severity system.

Comment 9

[❌ Anna Yeddi [:ayeddi] ❌ On leave until 2027-01-04]

The issue still exists in 119 Nightly, after long scrolling the lazy loading of the page is hanging and the A11y Inspector keeps showing loaders for the just loaded containers and the eye dropper tool stops selecting elements on hover (even those that are already loaded). The browser needs to be forced to quit to restore its functionality.

That being said, if the page has already loaded the content (the long scrolling has already happened) before the A11y Inspector is opened, there were no issues with the eye dropper tool on my macOS machine. The issue is not observed with the HTML inspector

Marking as a11y-S3 because there is a workaround (load the page before starting the eye dropper a11y inspector tool)