Performance myths in android

We know reflection or enum are contentious topics, but do they cause *real* performance problems? Let's see!

Transcript

1. Performance myths in Android Javier Gamarra / @nhpatt
2. “Why is this important?”
3. “Please try again soon!”
4. Performance is another feature of your app like … login
5. Performance is … CPU … memory … network … battery … smoothness
6. Always measure first
7. Tools! --using the right tool for the job
8. Performance monitors
9. Android device monitor
10. GPU Overdraw
11. Leak Canary
12. Hierarchy view
13. Allocation tracker
14. Traceview
15. Traceview
16. GPU profiler
17. HProf
18. systrace
19. Battery historian
20. External tools (nimbledroid…)
21. Use an old device
22. Be pragmatic
23. FACTS or MYTHS?
24. “things the community is very passionate about”
25. lots of things...
26. iosched
27. “Own” methods Without games and not counting library methods
28. Methods in most popular apps -facebook -facebook chat -twitter
29. 1 DATABASES
32. Record actual performance “Write” Espresso tests Rewrite database “layer” Measure time to finish Check allocation tracker Check traceview
33. Use Case 1 (first use) 4,18MB 78,8% parsing 2,5 TV seconds 8,8 seconds
34. Use case 2 (remotely) 4,23MB 13% drawing 1,64 TV seconds 4,28 seconds
35. Use case 3 (normal) 4,83MB 13% drawing 2,54 TV seconds 4,82 seconds
37. “Realm objects can only be accessed on the thread they were created”
39. 0’0%
41. ORM performance doesn’t matter
42. Do NOT choose an ORM because performance
43. I'll take something 10-20% slower that offers better APIs for the very reason that you'll never get close to the limits -- Jake
44. 2 DI FRAMEWORKS
45. How slow is reflection?
46. ... pretty much when done a lot 700 ms to NYTimes 660 ms to photobucket ...like JSON/XML parsing
47. And in DI frameworks?
48. Synthetic app with 5455 injections: Roboguice: 3923 ms Dagger1: 154ms Dagger2: 62 ms
49. “Roboguice would (...) be (...) a mere 5 times [slower] compared to Dagger”
50. Synthetic app with 5455 injections: Roboguice: 3923 ms Dagger1: 154ms Dagger2: 62 ms Directamente: 39ms
51. 3 REACTIVE LIBRARIES
52. <BS> about lazyness
53. Shakespeare plays scrabble
54. Range
55. When Not to Use RxJava Small, constant datasets Expensive objects Many flatmaps
56. = 8x slower to iterate
57. 4 PART04 MICRO OPTIMIZATIONS
58. Enums -- like 285 bytes lost
59. “If you use integer constants instead of enums in your Android app you are a fool” --Jake Wharton
60. We use enums regularly because they are safer than Strings or ints and their performance downsides are minimal --instagram
61. OnClickListeners?
62. How much costs to iterate between 1M likes?
63. 300 ms 30 MB
64. JSON parsing Network requests
65. LAST WORDS
66. Things I like/UI • Flat layout hierarchy • Merge tags • Optimized bitmaps • Inexistent alpha
67. Things I like/code • WeakReferences • Caches • FlatBuffers • Developer Efficiency
68. “Do the simple thing first … and optimize what matters”
69. Ok, dagger/rx/ORM is slow but does it matter to you?
70. ？ QUESTIONS? @nhpatt / twitter gmail github ...
71. THANKS
72. References • Awesome list • Google+ community • High performance programming book • Performance Testing Tools • Speed up your app
73. “If you care more about performance than correctness why using a computer at all?” I can give you the wrong answer faster than any machine ;) -- Mario Fusco
74. Performance myths in Android Javier Gamarra / @nhpatt