http://www.paug.fr

1. (Code for Responsiveness)
Thinking of CPU & Memory

2. Done!
The app works!

3. Why?
25% of people leave a web page if it takes more than 4
seconds to load

4. why?
● Amazon: +100ms = -1% sales
● Google: going from 0.4 seconds to 0.9 seconds loading
a page causes a 20% decrease of benefits
● I don't have data about smartphones, but IMHO is even
worse

5. The user is very
demanding
Mobile != Computer

6. The concept
Classic case:
1. Download some data
2. Parse
3. Download more data (images, audios, ...)
4. Load it on memory
5. Show it on screen

7. Don't be a Java Hero
It seems to me that Java is designed to make it
difficult for programmers to write bad code,
while Python is designed to make it easy to
write good code.” — Magnus Lycka, Aug. 18,
2005

8. How?
● Compile always with the latest SDK (hardware accel, ...)
● Splash-screens are evil
● Don't do work on UI Thread
● Don't block the UI (ProgressDialogs...)
● Efficient GetViews
● Don't download same data 2 times
● Fight for the 60fps

9. Speed

10. Strict Mode
.penaltyLog()
.penaltyDeath()

11. Network
(Public enemy #1)

12. DDMS (Network Statistics)
Red (Análisis)

13. 12s -> 0.4s (bad network, good smartphone)
Network - cache downloaded data
(this code isn't complete)

14. Cache:
● Universal-Image-Loader
● Picasso
Bandwidth:
● don't send too big bitmaps
● WebP (~-30%)
Bitmaps

15. CPU
Not everybody have a Nexus 4

16. Traceview (code y DDMS)
CPU (Analyze)

17. Cache objects
7s -> 0.8s (bad smartphone)

18. Show old data
always

19. RAM
If you don't share you get kicked

20. $ adb shell procrank
Keep the app in memory (Analyze)

21. Other tools to analyze memory usage
● adb shell dumpsys meminfo
● Heap dump
○ capture it with DDMS
○ +HeapDumpOnOutOfMemoryError
● MAT (Memory Analyzer Tool)
○ analyzes your heap dump
○ hprof-conv package.hprof package-converted.hprof
○ It has a stand-alone version if you don't want to use Eclipse

22. Keep the app in memory

23. Smoothness*
The wanted 60fps
*(Section "stolen" from Romain Guy)

24. Smoothness
● Profile GPU rendering (4.1)
● GPU Overdraw (4.2)
● Systrace (4.1)
● Hierarchy Viewer

25. Profile GPU Rendering
● profile last frames rendered
● You need to enable it on device (dev.options)
● you need <16ms per frame to get 60fps
● ddms -> System Information -> Frame render time

26. Systrace
● Enable on device (dev. options)
● tools/systrace/systrace.py or ddms

27. GPU Overdraw
● As a general recommendation
we can paint every pixel a max
of 3 times
● 9-patch for backgrounds
● lint can warn you about layouts
with possible overdraw

28. Hierarchy Viewer

29. ● PerfMon (memory, cpu, network on a floating window)
● Usage Timelines (cpu, memory)
Other tools

30. ● Save a long with start time on Application and show a
diff with current time on a toast when you are end
"printing" screen
● Send through analytics performance data
● You can do it on all parts of your app
Detect regressions

31. "Donald Knuth"
"Premature optimization is the root of all
evil"

32. References
● Google I/O 2012 - Doing More With less: Being a Good
Android Citizen
● Designing for Performance (developer.android.com)
● "Displaying Bitmaps Efficiently" Android Developers
● http://www.curious-creature.org/docs/android-performance-
case-study-1.html
● http://www.curious-creature.org/2012/12/06/android-
performance-in-practice/
twitter: @oriolj
+Oriol Jiménez