371885 - rendering 500 random height divs with float left style hangs browser

Status: RESOLVED WORKSFORME

(Core :: Layout, defect)

Description

[Jingshao Chen]

User-Agent:       Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8.1.1) Gecko/20061228 Firefox/2.0.0.1
Build Identifier: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8.1.1) Gecko/20061228 Firefox/2.0.0.1

When the number of divs exceed 300, the browser become very slow. 
The divs are 1 pixel width and random height. They are packed to the left by specify the ccs "float left". See reference web page for the test.

FF does not crash. But only becomes very slow and CPU utilization surges to 100%.

The same page does not have problem with IE or Opera.


Reproducible: Always

Steps to Reproduce:
1.go to http://www.teekoo.com/freebsd/chart.html
2.change the number of bars. Try 100 first, then 200, then 300, then 500 (this will lock up the browser)
3.Try the same page in IE. 
Actual Results:  
CPU 100% usage when the number of bars increase. browser hangs

Expected Results:  
Should be able to render thousands with out any performance penalty.

if "float left" style is removed, (horizon bar), the problem disappeared.

Comment 2

[Boris Zbarsky [:bzbarsky]]

This is a different issue.  See bug 350228 comment 13.

The testcase is in the URL field.  The old URL is http://www.teekoo.com/freebsd/chart.html

Comment 3

[Jingshao Chen]

Are there any plan on how to fix the bug?

Comment 4

[Boris Zbarsky [:bzbarsky]]

Uri, if you're redesigning space manager want to keep this in mind?

Comment 5

[Uri Bernstein]

(In reply to comment #4)
> Uri, if you're redesigning space manager want to keep this in mind?
> 

I think you might be confusing me with someone else here. I barely have time these days to look at regressions I caused, and I never expressed an interest in redesigning space manager.

Comment 6

[Phoenix]

Issue still here, despite for dualcore 2.7 GHz cpu you need to use 2000 bars to reproduce, IE8 performs without problem in same conditions
Mozilla/5.0 (Windows NT 5.1; rv:13.0) Gecko/20120227 Firefox/13.0a1

Comment 7

[Mats Palmgren (inactive)]

I see about 7-8% CPU time in nsLineBox::IndexOf, bug 730769 fixes that.

Comment 8

[Phoenix]

Mozilla/5.0 (Windows NT 5.1; rv:14.0) Gecko/20120420 Firefox/14.0a1
With 3000 bars FF uses 33% of CPU, while IE8 only 11%, on 5000 bars FF completely consumes one core and became irresponsible, while IE8 uses only 14% in same conditions...

Comment 9

[Hallvord R. M. Steen [:hallvors]]

This seems improved - a lot :) Firefox can render 4000 bars without problems on a fast Windows machine (although it gets a bit janky with 3000 or above on a somewhat slower Ubuntu laptop).