505328 - Resizing Samoa Wikipedia page will hang FF (speculate, floating items width calculation)

Status: RESOLVED WORKSFORME

(Core :: Layout, defect)

Description

[u348128]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; nl; rv:1.9.1.1) Gecko/20090715 Firefox/3.5.1 (.NET CLR 3.5.30729)
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; nl; rv:1.9.1.1) Gecko/20090715 Firefox/3.5.1 (.NET CLR 3.5.30729)

This is a split of bug 500103. That bug is about a crash, but somehow the Samoa page was mentioned.

If you go to the Samoa site and you resize as shown in the attachment (which I will add in next comment), then Firefox hangs. You need right size of font, maybe slightly different fonts on Mac/Linux prevent reproduction.

In general this is also a poor performance bug. Resizing close to the hang situation is sluggish.

Reproducible: Always

Steps to Reproduce:
1. Go to Samoa page on English Wikipedia.
2. Resize as shown in attachment.
3.
Actual Results:  
Hang

Expected Results:  
No hang.

Speculation:

The FF algorithm to calculate width gets into a infinite loop. Close to the hang situation the horizontal scroll bar suddenly gets shorter (meaning the width larger). This may be the result of the floating items on left and right. If the new width leads to other sizing problems on another part of the page, this may lead to again a new width calculation.

As said, this is speculation purely based on the visible behavior.

The test case is VERY hard to reduce. Removing parts often makes the case not reproducible anymore.

I have seen some bug in bugzilla, that might be a dupe of this bug.

Comment 1

[u348128]

Attachment: Resize the Samoa page exactly as in the picture. It must be pixel accurate.

Be sure you have the same sized fonts.

Resizing is very slow close to the hang situation.

Comment 2

[u348128]

It might be related to bug 505074. Little bit same behavior, also a website with difficult width calculation.

Comment 3

[Aaron Train [:aaronmt]]

Confirmed hang on Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1.1) Gecko/20090715 Firefox/3.5.1

Comment 4

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Is this a regression from 3.0?  If so, do we know when (on mozilla-central) it regressed?

Comment 5

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

After considerable resizing both on *nix and windows I say WFM