1134521 - Browser hangs when trying to sort a large file list alphabetically on SourceForge

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Ryan VanderMeulen [:RyanVM]]

Attachment: profile

On this page (with a huge list of files):
http://sourceforge.net/projects/msys2/files/REPOS/MSYS2/i686/

Clicking the Name header to sort by name, produces a ~50s hang on my W530 laptop. Chrome also hangs, but for a much shorter duration. Attached is the profile I took from the devtools, though I have no clue what it's saying other than that we spend most of the time within one function.

Comment 1

[Boris Zbarsky [:bzbarsky]]

OK so I see us taking about 2x as long as Chrome here (25s vs 12s).

Profile says the following are the most obvious things:

15% jitcode
22% document.querySelectorAll
13% str_replace with a regexp.
10% Element.className gets (which suggests there are a _lot_ of them).
 9% GetElementIC::update
 8% jit::RegExpReplace
 7% CallProperty doing a GetProperty that involves PrimitiveToObject and
    StringObject::init; I haven't checked which prop we're calling and why it's a slow
    path.
 7% SetObjectElement (SetNonexistentProperty, Shape::search, etc).
 4% GC off interrupt checks.
 2% DoCallFallback doing a js_fun_apply.
 2% Node.nodeType gets
 2% js::ConcatStrings

Comment 2

[Boris Zbarsky [:bzbarsky]]

Oh, and I used a profile with the slow script dialog turned off.  Obviously normally this sort of thing should trigger the slow script dialog....

Comment 3

[Boris Zbarsky [:bzbarsky]]

Also note that I did not profile for the full 25 seconds, but 5-6 seconds in the middle there, so it's possible that there are different things going on later on.

Comment 4

[Boris Zbarsky [:bzbarsky]]

Worth retesting with bug 1410624 fixed.