Relevance of code minification in a performance world

R8 and Proguard are Android developer's go-to tool for code minification. As a developer, inconsistent proguard rules can affect your application in more ways than you know. This talk will focus on code minification and it's additional impacts, divided into 3 parts
- Small introduction to code obfuscation and minification.
- Introduction to proguard rules, common mistakes and how to avoid them.
- A deep dive on how performance of app is impacted by proguard rules.

Transcript

1. Relevance of code minification in a performance world Jitin Sharma GDE Android, Gojek Android Worldwide jitinsharma.com @_jitinsharma
2. What we’ll discuss • Code obfuscation and minification • Introduction to obfuscation tools • Proguard rules • Performance impacts of code minification • Common mistakes and how to avoid them
3. Obfuscation
4. Life of code Kotlin Class dex Source code Bytecode Bytecode
5. Life of code Kotlin Class dex Source code Bytecode resources + apk
6. Life of code Kotlin Class dex Source code Bytecode Bytecode • dedexer • smali
7. Life of code Kotlin Class dex Source code Bytecode Bytecode jadx
8. Obfuscation class Repository viewModel.fetchData() fun matchUser() val loggedIn = false package com.awesome.app class a c.zz() fun rt() val y = false package com.g.f
9. minification
10. Minification fun main() { fetchUser() } fun fetchUser() { fetchProfile() } fun fetchProfile() { displayProfile() } fun displayProfile() { .. } main() fetchUser() fetchProfile() displayProfile()
11. Minification fun main() { fetchUser() } fun fetchUser() { // fetchProfile() } fun fetchProfile() { displayProfile() } fun displayProfile() { .. } main() fetchUser() fetchProfile() displayProfile()
12. Minification fun main() { fetchUser() } fun fetchUser() { // fetchProfile() } fun fetchProfile() { displayProfile() } fun displayProfile() { .. } main() fetchUser() fetchProfile() displayProfile()
13. Minification Activities Service Application Receivers Code
14. Minification Activities Service Application Receivers Code resources
15. Tools
16. Proguard Dexguard R8
17. Android Toolchain Code (source code + libraries) Obfuscation + minification D8/R8 minified dex AGP Toolchain (removes unused resources) manifest, resources apk dex/IR
18. Android Toolchain Code (source code + libraries) dex/IR minified dex AGP Toolchain (removes unused resources) manifest, resources ResourceUsageAnalyzer.java apk Obfuscation + minification D8/R8
19. Rules
20. Rules fun main() { val clazz = Class.forName() val method = clazz.getDeclaredMethod() method.invoke() } main() method()
21. Rules fun main() { val clazz = Class.forName() val method = clazz.getMethod() method.invoke() } main() method() Classes Fields Interfaces Functions
22. Rules - keep class … - keepclassmembers … - keep attributes … - dontwarn …
23. Optimisation and Performance
24. Test bed project ~20 modules, 100 classes, 6000 methods androidx Rxjava Glide Kotlin AGP 4.1 D8/R8
25. Comparison App Type Size App Launch Mode Non Minified 11.8MB 596.6ms Release Minified 6.5MB 367.9ms Release Minified + Shrinked 6.4MB 361.3ms Release
26. 11.8 mb 596.6 ms 6.4 mb (45%) 361.3 ms (39%) Non Minified Minified
27. Optimisations
28. Code Inlining fun myBranchedFunction() { if (BuildConfig.DEBUG) { debugMethod() } else { releaseMethod() } } fun myBranchedFunction() { releaseMethod() }
29. Code Inlining fun myBranchedFunction() { releaseMethod() } fun main() { myBranchedFunction() myFunction2() }
30. Code Inlining fun myBranchedFunction() { releaseMethod() } fun main() { releaseMethod() myFunction2() }
31. Code Inlining if (Build.VERSION.SDK_INT >= 21) { window.statusBarColor = .. } if (Build.VERSION.SDK_INT >= 28) { val displayCutOut = decorView.rootWindowInsets.displayCutout ... } minSdk 19 if (Build.VERSION.SDK_INT >= 21) { window.statusBarColor = .. } if (Build.VERSION.SDK_INT >= 28) { val displayCutOut = decorView.rootWindowInsets.displayCutout ... }
32. Code Inlining if (Build.VERSION.SDK_INT >= 21) { window.statusBarColor = .. } if (Build.VERSION.SDK_INT >= 28) { val displayCutOut = decorView.rootWindowInsets.displayCutout ... } minSdk 21 window.statusBarColor = .. if (Build.VERSION.SDK_INT >= 28) { val displayCutOut = decorView.rootWindowInsets.displayCutout ... }
33. Code Inlining if (Build.VERSION.SDK_INT >= 21) { window.statusBarColor = .. } if (Build.VERSION.SDK_INT >= 28) { val displayCutOut = decorView.rootWindowInsets.displayCutout ... } minSdk 28 window.statusBarColor = .. val displayCutOut = decorView.rootWindowInsets.displayCutout ...
34. Code Inlining fun trim(String name) { Intrinsics.checkParameterIsNotNull(name) name(…) } fun trim(String name) { if (name != null) { name(…) } else { // exception } }
35. App Startup 596.6 ms 361.3 ms (39%) Non Minified Minified
36. App Startup Non Minified Minified
37. App Startup Non Minified Minified Dex load: 2.96 ms Dex load: 0.07 ms
38. Systrace Event Non minified Minified Mode bindApplication 54.46 ms 19.24 ms Release ResourcesManager#getRes ources 4.62 ms 3.97 ms Release ResourcesImpl#updateCon figuration 3.98 ms 2.62 ms Release LoadApkAssets 1.3 ms 0.68 ms Release VectorDrawable#inflate 0.41 ms 0.39 ms Release
39. Rules
40. Rules can hurt you - keep class com.mypackage.** - keep com.somepackage.R$* - keepclassmembers enum * { public static **[] values(); public static ** valueOf(java.lang.String); }
41. Case Study keepclassmembers class **.R$* { public static <fields>; }
42. Transitive R classes App Module1 Module2 Module3 Module4 Module5 aar aar aar aar
43. Transitive R classes App Module1 Module2 Module3 Module4 Module5 aar aar aar aar R.class R.class R.class R.class R.class R.class R.class R.class R.class
44. 11.8 mb 596.6 ms 6.4 mb (45%) 361.3 ms (39%) Non Minified Minified
45. 6.4 mb 361.3 ms Minified 6.6 mb (+3%) 487.1 ms (+34%) Minified with faulty rules
46. 6.4 mb 361.3 ms Minified 6.6 mb (+3%) 487.1 ms (+34%) Minified with faulty rules Dex Count: 1 Dex Size: 634KB Dex load: 0.07ms Dex Count: 2 Dex Size: 894KB Dex load: 0.09ms
47. Rules • Be aggressive instead of defensive when defining proguard rules. • Avoid wildcard package rules. • Use @Keep to attach rules to codebase instead of rules files. • Scan for rules which third party rules are importing in your codebase.
48. Imported Rules proguard-rules.pro -printconfiguration
49. Imported Rules proguard-rules.pro -printconfiguration build/outputs/mapping/release/configuration.txt
50. Further Optimisations proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' proguardFiles getDefaultProguardFile(‘proguard-android-optimize.txt’), 'proguard-rules.pro'
51. Further Optimisations gradle.properties android.enableR8.fullMode=true
52. Debugging Rules -addconfigurationdebugging
53. Proguard Playground https://playground.proguard.com/
55. Further Reading • https://developer.android.com/studio/build/shrink-code • https://www.zacsweers.dev/android-proguard-rules/ • https://jakewharton.com/blog (Search for R8 optimization)
56. Thanks @_jitinsharma