Weekly Engineering Newsletter 2011-07-06

Here's your 25th edition of the Weekly Engineering Newsletter.

*Planning Update*

Yesterday (2011-07-05) was migration day and we did it without closing 
mozilla-central. That's kinda cool.

We took about 2,100 change sets that had landed on mozilla-central over 
the last six weeks and we uplifted them to Aurora. Builds of the new 
Aurora [Firefox 7] have been generated and are in testing now. If all 
goes well with that testing, we should be pushing them out to all of our 
people using the Aurora channel on Thursday (2011-07-06).

If that's confusing to you, go re-read this blog post: 
http://blog.mozilla.com/channels/2011/05/11/merge-dates-v...

We also took all the work that's happened over the last six weeks on 
Aurora (and the six weeks before that on mozilla-central) and migrated 
that up to Beta. Builds of the new Beta [Firefox 6] are also in the 
hands of QA and we hope to push those out to our Beta channel people on 
Friday (2011-07-06). The Firefox 6 Beta update will be for both Desktop 
and Mobile. We are now less than six weeks away from shipping Firefox 6 
to the world. It's gonna be awesome!

So, that means that mozilla-central is now at the beginning of the 
Firefox 8 cycle. If you've got big things planned for 8 (I'm looking at 
you Type Inference) then you're gonna want that stuff to land real soon 
now so it can get maximum shake-out time before the next uplift.

Finally, we're looking at a potential update to Firefox 5 because of a 
new and serious crasher that our Firefox 5 users would hit when they 
update to Mac OS X 10.7 (Lion). Lion's expected to ship before Firefox 6 
(which contains a complete fix for this problem) so we're probably going 
to have to do something sooner. A fix would be a very minor change and 
limited to just Mac users. We'll have more news as that plan comes together.


*Must Read Blogs & News*

Jay Sullivan - Firefox Product Vision Statement
https://wiki.mozilla.org/Firefox/VisionStatement

Nicholas Nethercote - MemShrink progress, week 3
http://blog.mozilla.com/nnethercote/2011/07/06/memshrink-...

Joshua Cranmer - DXR alpha 2 release
http://quetzalcoatal.blogspot.com/2011/07/dxr-alpha-2-rel...

Nicholas Nethercote - Faster JavaScript parsing
http://blog.mozilla.com/nnethercote/2011/07/01/faster-jav...

Mozilla Add-ons Blog - Porting the Library Detector to the Add-on SDK
http://blog.mozilla.com/addons/2011/07/06/porting-the-lib...

Products Team - New Feature Page system coming this week!
http://blog.mozilla.com/products/2011/07/04/new-feature-p...

Chris Jones - pdf.js reached its first milestone
http://blog.mozilla.com/cjones/2011/07/03/pdf-js-first-mi...

Taras Glek - Telemetry Status
http://blog.mozilla.com/tglek/2011/07/01/telemetry-status/


*Cool Features & Fixes*

Per-compartment memory reporters - Gives technically-oriented users a 
way to tell which web sites are causing high memory usage. Helps Mozilla 
developers identify problem site patterns and better optimize Firefox 
for those cases.
https://bugzilla.mozilla.org/show_bug.cgi?id=661474

GC more often using a timer - Background: GC was previously triggered 
only by allocation, so GCs were not triggered during idle time even if 
there was lots of garbage. "Basically, it fixes the ?I left Firefox 
running overnight and now my machine has locked up' problem." This 
reduced idle memory usage by 70-370 MB in some user-reported scenarios. 
Awesome!
https://bugzilla.mozilla.org/show_bug.cgi?id=656120

Dedicated memory allocator chunks for system objects - long-lived system 
objects would be allocated interspersed with other objects in the same 
1MB chunks, so those chunks could never be reclaimed. njn measured a 30% 
reduction in JS heap size during general browsing and a 5x improvement 
in JS heap size after closing all tabs. This should help dramatically 
with the "I closed all my tabs and Firefox is still holding onto that 
memory." problem.
https://bugzilla.mozilla.org/show_bug.cgi?id=666058


*Meetings I Went To So You Didn't Have To*

Weekly Firefox/Gecko Development Meeting:
https://wiki.mozilla.org/Platform/2011-07-05

Weekly Product Planning Meeting:
https://wiki.mozilla.org/Firefox/Planning/2011-07-06

Thrice-Weekly Aurora Meeting:
https://wiki.mozilla.org/Firefox/Aurora/2011-07-05
https://wiki.mozilla.org/Firefox/Aurora/2011-06-30