Firefox/Platform Engineering Update 40.1

This engineering update is also available on the Platform wiki:

https://wiki.mozilla.org/Platform/2015-04-24


# FIREFOX RELEASE SCHEDULE

We shipped a Firefox 37.0.2 chemspill which added some old Intel GPUs to 
our GPU blocklist.

Only two weeks until the next Firefox release: 2015-05-11!

https://wiki.mozilla.org/RapidRelease/Calendar


# LAYOUT (David Baron)

Off-main-thread animations now enabled on all platforms for Nightly and 
Aurora (bug 980770). This means many animations of the transform and 
opacity properties will now run on the compositor thread, with fewer 
updates on the main thread.


# MEDIA (Chris Peterson)

We shipped some MSE fixes in the Firefox 37.0.2 chemspill, so YouTube 
will re-enable HTML5 video for Firefox 37 on Windows next week.


# PERFORMANCE (Vladan Djeric)

Aaron Klotz and Ben Turner paid a visit to Adobe’s Flash team at their 
SF offices. They were able to provide fixes for several Flash player 
issues! An example of their work is in bug 1133351. This particular 
patch also landed in our codebase.

Many Telemetry histograms automatically expired in Nightly 40. Check 
Histograms.json and bug 1156565 to see if your histogram needs to be 
updated.

Telemetry unification work is continuing, Phase 3 is tracked in bug 
1120356. Enabling unified Telemetry (i.e. FHR + Telemetry) might get 
pushed back to Firefox 40.

Among the latest Telemetry changes, Telemetry will submit data more 
aggressively to make analyses more reliable (akin to FHR) and to reduce 
reporting latency. Additionally, unified Telemetry now archives 
Telemetry data on the client for 6 months — this archive will be used to 
power the Firefox Self-Support feature.

Yoric added a “Task Manager” feature to Nightly 40 (bug 674779) to 
identify tabs and add-ons that are consuming the main thread’s time and 
slowing down Firefox. Specifically, it reports the time spent by the 
main thread inside different JS compartments. You can see a very rough 
UI for this feature by opening about:performance in Nightly. For 
overhead reasons, the feature currently does not measure time spent in 
compartments belonging to Firefox’s own chrome JS code.

The Performance team, alongside Platform teams, will be studying page 
scrolling & page navigation performance on desktop & Android in Q2: 
https://wiki.mozilla.org/Firefox/Content_Performance_Program

The Places database work done by the “Forget” toolbar button, the 
“Forget Site” history-menu feature, and the “Clear recent history” 
feature has been moved off the main thread (bug 1076775). Less jank!

If you notice any plugin issues (crashes, videos not loading, etc), 
please file a bug and mark it as blocking the async plugin 
initialization feature (bug 1116806).
_______________________________________________
dev-planning mailing list
[email protected]
https://lists.mozilla.org/listinfo/dev-planning