339477 - tabbrowser.xml's observer destructor never gets called, leaking mTabClipWidth at shutdown

Status: RESOLVED FIXED

(Firefox :: Tabbed Browser, defect)

Description

[Adam Guthrie]

Found this using dbaron's leak monitor extension.

Steps to reproduce:
1. Install the extension.
2. Start Firefox; close Firefox.

Results:
On shutdown, the following is printed to the console:
LeakReport:
[+] [leaked object] (8671950) = [object XULElement @ 0x86907d0 (native @ 0x86a4830)]
 [ ] mTabClipWidth = 140

Expected results:
No leak.

I put some dumps in the destructor and found that it's never called. This can be solved my making the addObserver call to the pref. hold a weak reference to the observer, but I don't know what the possible side effects of this are.

Comment 1

[Mike Connor [:mconnor]]

I'm curious why the destructor isn't being called, but in the absence of a good reason, the weak ref is perfectly acceptable.

Comment 2

[Adam Guthrie]

Attachment: hold weak ref. to observer

Comment 3

[Mike Connor [:mconnor]]

Comment on attachment 223702 [details] [diff] [review]
hold weak ref. to observer

If we're holding the weak ref, just drop the removeObserver call and I guess the whole destructor

Comment 4

[Adam Guthrie]

Attachment: hold weak ref. to observer and kill destructor

OK. I had a feeling I should do that, but I wasn't sure.

Comment 5

[Joey Minta]

Patch landed on trunk and 1_8 branch

U toolkit/content/widgets/tabbrowser.xml
RCS file: /cvsroot/mozilla/toolkit/content/widgets/tabbrowser.xml,v
retrieving revision 1.149
retrieving revision 1.150

Checking in toolkit/content/widgets/tabbrowser.xml;
/cvsroot/mozilla/toolkit/content/widgets/tabbrowser.xml,v  <--  tabbrowser.xml
new revision: 1.103.2.42; previous revision: 1.103.2.41

Comment 6

[(not reading, please use [e-mail] instead)]

see also bug #340547, which contains a supplimental patch for this issue