299779 - Complete freeze with max CPU usage + hourglass when creating selections around form elements

Status: RESOLVED DUPLICATE of bug 299533

(Core :: Layout, defect)

Description

[Jonas Nordlund]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b2) Gecko/20050703 Firefox/1.0+
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b2) Gecko/20050703 Firefox/1.0+

Certain text selections seem to cause a browser hang; seems especially common
when working with forms. I first believed this was bug 256774 or similar freeze
bugs that I've looked at, but as opposed to bug 256774, even cycling tabs do not
work. As opposed to some other bugs, it also causes maximum CPU usage, and hence
not an "idle freeze". It also does not freeze when executing form actions, such
as form submits. It occurs when performing various web page content selections
with your mouse, particularly seemingly when form objects are involved. It also
does not occur automatically when entering or leaving a page.

Reproducible: Always

Steps to Reproduce:
1. Login and visit the "My Controls" section on an Invision Power Board forum
(tested with IPB 1.3 so far) *OR* "Profile" in a phpBB board.

If IPB:
2a. Click "Edit Signature".
3a. Click, and HOLD DOWN the mouse button BEFORE the "Update my Signature" button.
4a. Move around the mouse while HOLDING DOWN the button, as if you'd wish to
select this entire row.

If phpBB:
2b. Click, and HOLD DOWN the mouse button BEFORE the "Submit" and "Reset" buttons.
3b. Move around the mouse while HOLDING DOWN the button, as if you'd wish to
select this entire row.
Actual Results:  
Firefox freeze/hang, with maximum CPU consumption and a hourglass. Everything
seems unresponsive including menu bar, toolbar, and tabs.

Expected Results:  
A modified text selection with a still responsive browser.

Extensions installed: ChatZilla, Adblock, DOM Inspector, Reporter, How'd I Get
Here, Session Saver .2 (which I installed to reduce the pain from my freezes)

I'm on Windows XP SP2 and my computer use HyperThreading. I have Fastback
enabled, as it is nowadays by default in these builds.

I don't recall encountering this problem in a nightly Firefox 1.1 trunk build
since about a month back.

Comment 1

[Jonas Nordlund]

Updated title: "max CPU usage" instead of "50% CPU". Although the latter is true
when looking at the Task Manager, it's actually 100% but with Windows confused
to believe it's 50% due to the HyperThreading technology. The old title would
likely just confuse.

Additional reproduction info: I can also confirm http://forums.mozillazine.org
show this behavior for me. Just go to that address, log in, then go to User
Links -> Profile, scroll all the way down that page, press and hold down the
mouse button before the "Submit" button on the horizontal bar with the "Submit"
and "Reset" buttons, and then move around the mouse with it kept depressed. If
nothing special hangs, try again, and don't be too careful in your mouse
movements. You can move it all around the page if you wish, with the mouse
button depressed and before the "Submit" button (i.e. to the left of it, and
centered on the horizontal gradient bar).

Comment 2

[Martijn Wargers (dead)]

Attachment: testcase

Comment 3

[Martijn Wargers (dead)]

Ok, this regressed between 2005-06-30 and 2005-07-01.
Possibly because of bug 297224.
But this might already be fixed with the fix for bug 299533.
That has to be checked with a 2005-07-06 nightly trunk build.

Comment 4

[Jonas Nordlund]

OK, with the fix for bug 299533 in, I can no longer reproduce this on
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b2) Gecko/20050706
Firefox/1.0+

It seems very likely this was a duplicate of that bug.

Sorry, will add "hang" to my list of synonyms to "freeze", "crash" and "lock"
when searching for bugs.


*** This bug has been marked as a duplicate of 299533 ***