Benchmarking your app's performance

In 1974, Donald Knuth said that “premature optimization is the root of all evil (or at least most of it) in programming”. But optimizing without benchmarks would be like following your instinct trying to get to your destination with a map but without a compass; you hope that you’re going in the right direction, but could be wasting a lot of time and energy..

Whether it is during development or at runtime, many tools exist to let you measure the performance of your applications. These measures can then be used to prioritize which parts to optimize first, as well as measure the performances gained (or lost) after a refactoring.

Based on various concrete examples, this talk will focus on measuring Android code using the Jetpack Benchmark library, as well as exploring how Datadog’s Android SDK can help measure app performance in real life.

Transcript

1. Benchmarking your app’s performance Xavier F. Gouchet, Senior Software Engineer / Team Lead @xgouchet (Twitter, GitHub, SpeakerDeck)
3. Introduction A few words about performance 0
4. Mobile app performance is still critical today - Low end devices - Slow networks - Short attention span 4 @priscilladupreez
5. Performance (like Android) are fragmented If you develop on a Pixel 5, make sure your app also works correctly on a Samsung Galaxy S8 (2017) 5
6. Performance must be measured You can’t just base your roadmap decision on “a hunch” 6 @youngprodigy3
7. User will tell you it feels slow Measurements will tell you what part exactly is slow. #MeasurementsMatter Changes must be measured Measurements will tell you how much your PR improves (or degrades) your feature’s performance 7
8. 8 Making sure the code works - Unit Testing - Instrumented Testing - Manual Testing - <insert testing paradigm> - … In your toolbox Making sure it works fast and efficiently - ???
9. Developer Tools Get a snapshot of your immediate performance 1
10. Immediate snapshot Get a full view of: - network - cpu - heap - rendering - … 10 @kmuza
11. 11 Tools Android Studio Profiler Systrace Perfetto
12. 12 Android Profiler
13. 13 Android Profiler Touch Activities Fragments
14. 14 Android Profiler CPU usage
15. 15 Android Profiler Memory usage
16. 16 Android Profiler Network usage
17. 17 Android Profiler Battery impact
18. 18 Android Profiler
19. Launching systrace $ systrace.py 19
20. Launching systrace $ systrace.py Starting tracing (stop with enter) 20
21. Launching systrace $ systrace.py Starting tracing (stop with enter) Tracing completed. Collecting output... Outputting Systrace results... Tracing complete, writing results 21
22. 22 Systrace (legacy)
23. 23 Perfetto showing systrace result
24. 24 Recording from Perfetto (API 28+)
25. 25 Recording from Perfetto (API 28+)
26. fun methodWithCustomEvents() { Trace.beginSection("MySectionName") // … Trace.endSection() } 26 Custom Traces
27. 27 Recording from Perfetto (API 28+)
28. 28 Recording from Perfetto (API 28+)
29. Pros 👍 ▫ (Almost) no setup required ▫ Get full system state info ▫ Controlled scenario and environment 29 Profiler / Systrace / Perfetto Cons 👎 ▫ Performance measurements are skewed ▫ Needs manual trigger ▫ Complex and dense UI/UX
30. When should you use it ? ▫ When you have a specific performance issue ▫ When you want to optimize a specific part of the code ▫ To debug a tricky algorithm (nested loops, concurrency) 30
31. Going Further ▫ Capture systrace from the device (API 28+) 31
32. 32 Capturing traces from the developer settings
33. Benchmark Standardized performance measurement 2
34. Benchmark Overview Measure timed performances of specific operations 34 @veri_ivanova
35. 35 Tools Jetpack Benchmark CI Provider
36. Jetpack Benchmark Library dependencies { // … androidTestImplementation "androidx.benchmark:benchmark-junit4:1.0.0" } 36
37. Jetpack Benchmark Library android { // … defaultConfig { // … testInstrumentationRunner "androidx.benchmark.junit4.AndroidBenchmarkRunner" } } 37
38. @RunWith(AndroidJUnit4::class) class BenchmarkTest { @get:Rule val benchmarkRule = BenchmarkRule() // … } 38 Benchmark Test Class
39. @RunWith(AndroidJUnit4::class) class BenchmarkTest { @get:Rule val benchmarkRule = BenchmarkRule() // … } 39 Benchmark Test Class
40. @RunWith(AndroidJUnit4::class) class BenchmarkTest { @get:Rule val benchmarkRule = BenchmarkRule() // … } 40 Benchmark Test Class
41. @Test fun benchmarkSomeWork() { benchmarkRule.measureRepeated { doSomeWork() } } 41 Benchmark Test Function
42. @Test fun benchmarkSomeWork() { benchmarkRule.measureRepeated { doSomeWork() } } 42 Benchmark Test Function
43. @Test fun benchmarkSomeWork() { benchmarkRule.measureRepeated { doSomeWork() } } 43 Benchmark Test Function
44. @Test fun benchmarkSomeWork() { benchmarkRule.measureRepeated { doSomeWork() } } 44 Benchmark Test Function
45. @Test fun benchmarkSomeWork() { benchmarkRule.measureRepeated { cleanState() val data = createData() doSomeWork(data) } } 45 Benchmark Test Function
46. @Test fun benchmarkSomeWork() { benchmarkRule.measureRepeated { runWithTimingDisabled { cleanState() } val data = runWithTimingDisabled { createData() } doSomeWork(data) } } 46 Benchmark Test Function
47. $ gradlew :benchmark_module:connectedCheck 47 Run the Benchmark
48. ▫ Stored in a JSON file ▫ Full timing information in nanoseconds 48 Benchmark Results
49. { "name": "benchmarkSomeWork", "className": "com.example.BenchmarkTest", "metrics": { "timeNs": { "minimum": 2561000, "maximum": 7133000, "median": 3914000, "runs": [ … ] } } 49 Benchmark Result
50. Running Benchmark in the CI ▫ Emulators are unstable, use real devices ▫ Needs some tweaks in your gradle config ▫ Use the JSON to: - Graph the evolution of performance - Fail if the measurements exceed a threshold 50
51. Pros 👍 ▫ Accurate*, reliable and consistent ▫ Measure just what you want ▫ Can be as high or low level as needed 51 Jetpack Benchmark Cons 👎 ▫ *Needs to be ran on a real device ▫ The feature to be tested must be repeatable and called from code ▫ Takes a long time in CI
52. When should you use it ? ▫ Monitor critical parts of your logic in CI ▫ When refactoring a specific feature ▫ When writing code executed on the main thread 52
53. ▫ Official Gradle plugin to lock the CPU clocks (root) ▫ Use CI script to fail on high measurements Going Further 53
54. Real User Monitoring Live performance from the trenches 3
55. What about the real users? Get performance and runtime information from the production environment 55 @robin_rednine
56. 56 Tools Real User Monitoring Error Tracking Android Vitals
57. 57 dependencies { implementation "com.datadoghq:dd-sdk-android:1.10.0" implementation "com.datadoghq:dd-sdk-android-ktx:1.10.0" // optional extensions: RxJava, Android NDK, … } Using Datadog SDK for Android
58. Single View Performance 58
59. Funnels 59
60. Network Performance 60
61. Mobile Vitals: Refresh Rate 61
62. Mobile Vitals: CPU usage 62
63. Mobile Vitals: RAM consumption 63
64. Application not responding 64
65. Application not responding 65
66. Error Tracking 66
67. Performance monitoring 67
68. Pros 👍 ▫ Real data - real use cases - real devices - real network conditions 68 App Performance Monitoring Cons 👎 ▫ Need large enough user base to have relevant data ▫ Can’t measure everything
69. When should you use it ? ▫ Monitor key aspects of your app in the wild ▫ Understand how performance and crashes impacts your users’ journey ▫ A/B testing / feature flags analytics 69
70. Going Further ▫ Library is Open Source on GitHub ▫ Also provides Logging and Tracing ▫ More features coming soon… 70
71. Wrapping up 4
72. Key takeaways “Measure twice, cut once.” 72 Choose the relevant tool to your use case. Always analyse your measurements before taking action.
73. 73 Useful links ▫ https:/ /ui.perfetto.dev/ ▫ https:/ /developer.android.com/studio/profile/benchmark ▫ https:/ /developer.android.com/studio/profile/run-benchmarks-in-ci ▫ https:/ /proandroiddev.com/jetpack-benchmark-on-firebase-test-lab-d1 4c5eae815f ▫ https:/ /github.com/DataDog/dd-sdk-android ▫ https:/ /docs.datadoghq.com/real_user_monitoring/android/
74. 74 Thank You! Any questions? ▫ @xgouchet ▫ @datadoghq @theunsteady5
75. CREDITS Special thanks to all the people who made and released these awesome resources for free: ▫ Presentation template by SlidesCarnival ▫ Photographs from Unsplash 75