1303352 - [e10s] Select box render extremely slow on large data sets

Status: RESOLVED DUPLICATE of bug 1118086

(Core :: Layout: Form Controls, defect)

Description

[blistovmhz]

User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36

Steps to reproduce:

Click select dropdown that is populated with a large data set (in this case, 38,000 records), to change selection.


Actual results:

If the select box "selected" item is in the first few thousand entries, the dropdown drops down instantly and renders normally. If however "selected" item is near the end of the list, the dropdown can take up to 30 seconds to render. During this time the CPU is pegged at 100% and FF becomes unresponsive. This issue is not present prior to version 47.0.1.  48 series always hangs up when clicking large selects.
I rolled a few users back to 47, and they no longer have any performance issue. The same select can be "selected" at entry 38,000 and renders instantly. Upgrade to 48 again and the same select takes 20-30 seconds to render.



Expected results:

Select dropdown should render quickly.

Comment 1

[blistovmhz]

I have also verified that there are no additional calls leaving the client machine (ie: fetching data) when the user clicks the select dropdown.
Incidentally, the most recent update to Chrome as of September 14 also now exhibits the same behavior. Again, rolling it back a version resolves the issue. Suspect Chrome copied some new functionality from FF to introduce the same bug.

Comment 2

[Loic]

Do you have a simple testcase?

Comment 3

[Ciprian Muresan [:cmuresan], Ecosystem QA]

User Agent 	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:52.0) Gecko/20100101 Firefox/52.0
Build ID 	20160920030429

I have managed to reproduce this issue on Ubuntu 14.04 x64 and on Windows 10 x64. Both on the latest Nightly and on Firefox release (48.0.2, with e10s enabled). In my case when I click the <select> dropdown the whole browser locks up and becomes unresponsive. 
With e10s disabled the dropdown menu loads and renders as expected both on Release and on the latest Nightly.

blistovmhz, could you please look in about:support and post what you find in "Multiprocess Windows"?

Comment 4

[Ciprian Muresan [:cmuresan], Ecosystem QA]

Attachment: LARGEDATASET.HTML

Attached the test case that reproduced the issue for me.

Comment 5

[Loic]

Yes, I can reproduce it with e10s enabled in Nightly, but not with e10s off. Same issue with old Nightly like FF40.

So it's clearly a perf issue with e10s.

Comment 6

[Jim Porter (:squib)]

This sounds like the same issue as bug 1118086, which has some analysis of the code that's causing the issue. Marking dupe.