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Relevance of code minification in a performance world

Jitin
October 27, 2021

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.

Jitin

October 27, 2021
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  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 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
  4. Minification fun main() { fetchUser() } fun fetchUser() { fetchProfile()

    } fun fetchProfile() { displayProfile() } fun displayProfile() { .. } main() fetchUser() fetchProfile() displayProfile()
  5. Minification fun main() { fetchUser() } fun fetchUser() { //

    fetchProfile() } fun fetchProfile() { displayProfile() } fun displayProfile() { .. } main() fetchUser() fetchProfile() displayProfile()
  6. Minification fun main() { fetchUser() } fun fetchUser() { //

    fetchProfile() } fun fetchProfile() { displayProfile() } fun displayProfile() { .. } main() fetchUser() fetchProfile() displayProfile()
  7. Android Toolchain Code (source code + libraries) Obfuscation + minification

    D8/R8 minified dex AGP Toolchain (removes unused resources) manifest, resources apk dex/IR
  8. Android Toolchain Code (source code + libraries) dex/IR minified dex

    AGP Toolchain (removes unused resources) manifest, resources ResourceUsageAnalyzer.java apk Obfuscation + minification D8/R8
  9. Rules fun main() { val clazz = Class.forName() val method

    = clazz.getDeclaredMethod() method.invoke() } main() method()
  10. Rules fun main() { val clazz = Class.forName() val method

    = clazz.getMethod() method.invoke() } main() method() Classes Fields Interfaces Functions
  11. 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
  12. Code Inlining fun myBranchedFunction() { if (BuildConfig.DEBUG) { debugMethod() }

    else { releaseMethod() } } fun myBranchedFunction() { releaseMethod() }
  13. 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 ... }
  14. 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 ... }
  15. 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 ...
  16. Code Inlining fun trim(String name) { Intrinsics.checkParameterIsNotNull(name) name(…) } fun

    trim(String name) { if (name != null) { name(…) } else { // exception } }
  17. 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
  18. Rules can hurt you - keep class com.mypackage.** - keep

    com.somepackage.R$* - keepclassmembers enum * { public static **[] values(); public static ** valueOf(java.lang.String); }
  19. 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
  20. 6.4 mb 361.3 ms Minified 6.6 mb (+3%) 487.1 ms

    (+34%) Minified with faulty rules
  21. 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
  22. 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.