Faster Builds on Android

I talk about the importance of faster builds and share tips to speed them up with Gradle and modularisation. Doing it right, you can change code in the business logic and run the tests for it in 2 seconds instead of 2 minutes.

Transcript

1. Make diabetes suck less
2. Testing Trophy
3. Write tests. Not too many. Mostly integration. By Kent C. Dodds
4. Faster Builds on Android From 2 Minutes to 2 Seconds @muffls Philipp Hofmann
5. Why is build speed important?
6. Scenario • 10 - 100 builds per day • Reduce build time by 118s • Save around 20 min to 2 hours per day • Save around 1,6 hours to 10 hours per week
7. Scenario • Reduce by 5 seconds • 20 builds * 5s * 10 devs * 5 working days = 1,4 hours
8. What do you do when you have to wait 2 minutes?
9. Or just 20 seconds?
11. Loose Focus
12. Multitasking is killing your brain.
13. Multitasking lets your IQ drop significantly.
14. Like skipping whole night sleep.
15. Or smoking weed. Image Source
16. Checking your email.
17. Knowing there is an unread email can reduce your IQ by 10 points!
18. Multitasking is especially bad for men.
19. It can reduce the IQ up to 15 points.
20. Turning you into a cognitive equivalent of an 8-year-old.
21. D Multitasking Is Killing Your Brain CREDIT: Getty Images
22. Slow builds = slow tests test automation is a pain
23. • Basic tips to tweak your builds • Modularisation • Gradle Build Scans • Some additional information about the topic on the chart • Maybe some numbers or a background information about some insights • Here is just another placeholder text to visualise the look of a filled info box INFO BOX Agenda • Basic Android knowledge appreciated • Tips for beginners • Example for experts to maybe learn something new INFO
24. Basic tips to tweak your build
25. Update Gradle
26. Update JVM
27. A word about dependencies
28. Don’t use dynamic versions, such as “2.+”
29. Avoid unnecessary and unused dependencies.
30. Consider copying a class from a third party library.
31. Transient dependencies can add a lot of costs.
32. Minimise the repository count.
33. Minimise the repository count. repositories { google() maven { url '../localmaven' } maven { url 'https://maven.fabric.io/public' } mavenCentral() jcenter() maven { url "https://jitpack.io" } flatDir { dirs 'libs' } }
34. Use incremental build kotlin.incremental=true
35. If neither a task’s inputs nor its output have changed since the last time it was run, Gradle will not run it again.
36. Cache task outputs org.gradle.caching=true
37. Use parallel builds org.gradle.parallel=true
38. Improving the Performance of Gradle Builds https://guides.gradle.org/performance/
39. Check your memory settings org.gradle.jvmargs= -Xmx3g -XX:MaxPermSize=2048m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8
40. Java Performance Tuning https://dzone.com/articles/java-performance-tuning
41. Use instant run
42. Create a build variant for development
43. flavorDimensions "mode" productFlavors { dev { dimension "mode" resConfigs "en", "xxhdpi" versionNameSuffix "-dev" applicationIdSuffix '.dev' signingConfig signingConfigs.debug buildConfigField "long", "TIMESTAMP", "0L" } full { dimension "mode" } }
44. Optimize your build speed https://developer.android.com/studio/build/optimize-your-build
45. Modularisation
46. Modules can speed up your build, but can also slow down your build.
47. Biggest benefit when modules can be built in parallel.
54. Change Run
57. 18 seconds when in layout
58. 7 seconds when in Fragment
59. Change Run
62. 6 seconds when in layout
63. 3 seconds when in a Fragment
64. Change Run
65. 65 seconds
66. Change Run
67. Change Run
68. 65 seconds
69. 9 seconds
70. Change BL code and run tests
71. first time ~30 seconds
72. second time 10-15 seconds
73. Change BL code and run tests
74. Change BL code and run tests
75. first time ~4 seconds
76. second time 4 seconds
77. I promised 2 seconds
78. Plain Kotlin or Java No Android dependencies
79. Demo of DefaultTapLevelCalculator
80. Advantages of multiple modules
81. Advantages of multiple modules • For big projects huge speed up, if done right. • Add smaller test app of a specific feature for very fast iterations. • Build and test them in parallel on CI. • Force developers to have a clear separation of concerns. • And all the other advantages … (Reusability, Maintainability, SOLID, …)
82. Spotify has over 600 modules.
83. 2015 2016 2017 2018 LOC in repo LOC NOT in the monolith LOC in the monolith
84. :app :features :common :libs :http :logger :audio :video :artist :search :ui :library :feed :profile :radio :radio :android :ui-tools :follow :share :mobius :dep-inj
85. Modularisation - How hard can it be? (Droidcon London 2018)
86. Scan your Builds
87. ./gradlew assembleDebug --scan
88. ./gradlew assembleDebug --scan BUILD SUCCESSFUL in 6s Do you accept the Gradle Cloud Services license agreement (https:// gradle.com/terms-of-service)? [yes, no] yes Gradle Cloud Services license agreement accepted. Publishing build scan... https://gradle.com/s/czajmbyg73t62
90. First build time
91. Enable Parallel Builds
92. Change one line in business logic
93. Splitting up into multiple modules
94. Don’t just blindly optimise
95. Scan Optimise
96. Conclusion
97. Build speed is important Image Source
98. Improving the Performance of Gradle Builds https://guides.gradle.org/performance/
99. Optimize your build speed https://developer.android.com/studio/build/optimize-your-build
100. Modules can speed up your build, but can also slow down your build.
101. I optimize the build speed!
102. Don’t just blindly optimise
103. Scan Optimise
104. Slides on Speakerdeck tomorrow. Check my twitter account @muffls
105. Feedback bit.ly/phil-feedback
106. Questions ?