1058423 - Hangs up at loading Ohloh Code Search

Status: RESOLVED WORKSFORME

(Core :: Disability Access APIs, defect)

Description

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

When I access following page in Ohloh Code Search, Firefox hangs up and CPU spikes up after showing the page contents.
http://code.ohloh.net/file?fid=7UyJXxx8y6GGv1-VeJSJ0JP9jIs&cid=hOh6fvYhQFU&s=ITfMouseTrackerACP&fp=491344&mp&projSelected=true#L0

I can reproduce this bug on both Firefox 31 and Nightly. And also I can reproduce this with safe mode.

On Google Chrome, I cannot reproduce this.

Comment 1

[Alice0775 White]

Setting accessibility.force_disabled = 1 seems to fix the high CPU usage problem.

Comment 2

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Thank you, Alice-san. I tested again. If I change the pref, I can load mxr (e.g., http://mxr.mozilla.org/mozilla-central/source/layout/base/nsPresShell.cpp) smoother.

So, something of a11y has serious performance issue on a lot of page.

Alexander Surkov, do you know something about this?

Comment 3

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

When I load nsPresShell.cpp of mxr, the profiler said:
http://people.mozilla.org/~bgirard/cleopatra/#report=af9390cc747b20f8d53d8befbfb612330e991980

According to the result of profile, following methods spend almost half of the time:

mozilla::a11y::Accessible::InvalidateChildrenGroupInfo()
mozilla::a11y::EventQueue::CoalesceReorderEvents(mozilla::a11y::AccEvent *)
mozilla::a11y::EventQueue::CoalesceEvents()

Comment 4

[alexander :surkov (:asurkov)]

bug 1041070 might help with it

Comment 5

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

(In reply to alexander :surkov from comment #4)
> bug 1041070 might help with it

Yeah, I confirmed that the patch of bug 1041070 fixes this bug.

Comment 6

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

I tested at nsPresShell.cpp in mxr.

In the default settings, perhaps by the fix of bug 1041070, the time to hang up is much shorter than I've experienced before. However, I still need long time to render the page. If I disable a11y module with |accessibility.force_disabled = 1|, I don't see any hanging up.

surkov:

Do you think that remaining cost is necessary? Or can improve with some hack? (e.g., using interruptable handling like layout)

Comment 7

[alexander :surkov (:asurkov)]

I bet we have some perf a11y issues to fix. Can you share a link at perf report?

Comment 8

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Okay, I'll do that later.

Comment 9

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

It's odd. I cannot reproduce this with prof-build on my development machine...
http://people.mozilla.org/~bgirard/cleopatra/#report=7b5f1d61b58e90f4478f7ea9b5fede66de77ae3e

I'll investigate what happens more. And if it's not caused by a11y module, I'll file another bug.

Comment 10

[Marco Zehe (:MarcoZ)]

Hi! Is this still a problem with current Firefox?

Comment 11

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

I cannot access the website, but I don't experience this bug on dxr nor searchfox anymore. marking this as WFM.