Talk given at the DroidCon London 2013 conference by Tyrone Nicholas, an engineer on Facebook's Android team.

1. Facebook on Android
DroidCon London 2013

2. Why we sucked
2009 – Wrap the Web
2012 – Go Native fast

3. Why we still suck have problems
Since Jan 2013:
Per user, per day:
Photos posted up
20%
Messages up 33%
Time spent up 25%
• 360 million users every month
• 200 million every day
• Feature surpass desktop web
Photo uploads
quadrupled

4. How can we not?
Emerging markets
40% of users still on Gingerbread or earlier
8 million users per day on Froyo
40% of users using old versions of the app

5. What we’ve achieved
Since January 2013:
20-30 new features per month
Crashes per user down 30%
APK size flat
Data usage flat

6. Do’s

7. Tradeoffs

8. Don’t
HTML5 doesn’t work
New Zealand is your friend
TechCrunch is not
Java on Dalvik is different
Beware server-side libraries like Guava
Purgeable bitmaps don’t help much

9. LinearAlloc
Dalvik loads metadata about each method into a fixed
5 MB buffer
We filled it up (bug fixed in HC)
We hacked into Dalvik’s memory space to increase
this size!
Tested across dozens of devices

10. What four lines can do
4-line change removed some extra data from logging
Reduced start time for FB Messenger by 10%
Ends up saving a year every day!

11. Bitmaps
Use up mountains of memory
Not garbage collected effectively GB and earlier
Leading cause of OutOfMemoryErrors
Rotating, resizing etc, loses purgeability

12. Bitmaps
Custom reference counting
Custom purgeability
Libjpeg-turbo

13. Questions?
Tyrone Nicholas
tnicholas@fb.com