36015 - Massive StyleChange reflows before browser comes up!

Status: VERIFIED DUPLICATE of bug 36485

(Core :: Preferences: Backend, defect, P3)

Description

[Eric Vaughan]

When ever a pref is loaded it causes a style change reflow of the entire window! 
This is very EXPENSIVE. This is why boxes are dumping Style change reflow 
messages when the browser first comes up. This really slows down our startup 
time.

To reproduce:

1) run the browser
2) select a profile.
3) Now for ever preference loaded you will get a Style Change reflow!!!

Comment 1

[Sean Richardson]

See also bug 36009, "rendering page causes processor to spike", a regression
in Today's M16 bits that may be related, if this only started happening today.

Comment 2

[neeti]

Erik, 
Is the StyleChangeReflow(..) method in nsCSSFrameContructor.cpp being called for 
every pref which gets loaded? If not, can you point me to the correct Style 
Style change reflow method. Also, what is the exact Style change reflow 
messages that are being dumped out when the browser starts up?

Thanks,
Neeti

Comment 3

[Eric Vaughan]

Yes the stylechange reflow in nsCSSFrameConstructor is being called for every 
pref that is loaded. 

Comment 4

[neeti]

By stepping through the code in the debugger, I find that 
PresShell::StyleChangeReflow(..) is being called "only" for prefs which have 
been registered for callback by nsPresContext while loading all.js. The prefs 
which have been registered by nsPresContext are

mPrefs->RegisterCallback("browser.screen_resolution", PrefChangedCallback, 
(void*)this);
D:\seamonkey\mozilla\layout\base\src\nsPresContext.cpp(308):    
mPrefs->RegisterCallback("browser.use_document_fonts", PrefChangedCallback, 
(void*)this);
mPrefs->RegisterCallback("browser.use_document_colors", PrefChangedCallback, 
(void*)this);
mPrefs->RegisterCallback("browser.background_color", PrefChangedCallback, 
(void*)this);
mPrefs->RegisterCallback("browser.foreground_color", PrefChangedCallback, 
(void*)this);
mPrefs->RegisterCallback("browser.base_font_scaler", PrefChangedCallback, 
(void*)this);
mPrefs->RegisterCallback("browser.wfe.use_windows_colors", PrefChangedCallback, 
(void*)this);
mPrefs->RegisterCallback("font.", PrefChangedCallback, (void*)this);
mPrefs->RegisterCallback("browser.display.direction", PrefChangedCallback, 
(void*)this);
pref->RegisterCallback("intl.charset.detector", MyPrefChangedCallback, nsnull);

It looks like a lot of calls, because all fonts prefs are registered.

Neeti

Comment 5

[sairuh (rarely reading bugmail)]

h'm, i still see this occurring --right after i select a profile and as the
browser launches, get a bunch of "STYLE CHANGE REFLOW. Blowing away all box
caches!!" in the console.

so, am gonna reopen this --neeti, should this go to someone else? thx!

Comment 6

[neeti]

*** This bug has been marked as a duplicate of 36485 ***

Comment 7

[sairuh (rarely reading bugmail)]

verif.