Efficient Kotlin

Доклад про языковые конструкции и методы stdlib'ы и их оверхед на рантайм. Предлагаются советы о том, что нужно делать, чтобы минимизировать этот самый оверхед.

Автор: Михаил Горюнов

Android-разработчик, иногда балуется back-endом.

Transcript

1. Efficient Kotlin-JVM Comparisons, precautions and gotchas Disclaimer: you may have different performance with the same code constructs. All measurements were performed with Kotlin 1.1.3 on 64-bit HotSpot (build 25.131-b11) and on Android 7.1.1
2. Flatten, filter and sort a list: Java 8 Truly functional: — concurrent processing — real lambdas — lambda creation overhead — virtual (interface) method invocation overhead fastest on big collections and with complex processing — stream creation overhead
3. Flatten, filter and sort a list: Kotlin — cute & concise — imperative bytecode: no real lambdas and virtual calls — no automatic concurrency, single-thread processing fastest on small collections (hundreds of elements)
4. functional syntax imperative bytecode
5. Create a new list
6. Create a new list
7. Create a new list
8. Create a new map malloc(24) malloc(24) malloc(24) malloc(24)
9. Create a new map malloc(24) malloc(24) malloc(24) malloc(24) ArrayMap See also: — slow & compact SimpleArrayMap — SparseArray, SparseIntArray, SparseLongArray, LongSparseArray
10. Difference between inline code & inline bytecode
11. Difference between inline code & inline bytecode
12. Difference between inline code & inline bytecode
13. Iterators Iterator is a common contract for all Iterables, i. e. Lists, Sets etc. ...but for ArrayList, the most common collection, positional access is faster.
14. For-each loops (HotSpot)
15. For-each loops (HotSpot) same sweet syntax, but no allocations
16. For-each loops (HotSpot)
17. For-each loops (ART)
18. Fastest loop for ArrayList • fastForEach (inlined for) in HotSpot • for (i in 0..size-1) in ART
19. Why different loops win? Want to run perfasm on ART? LOL, you’re funny.
20. Ranges: theory
21. Ranges: practice kotlinc intrinsic, allocation-free single allocation single allocation single allocation two allocations
22. Ranges: practice single allocation
23. SAM conversions – lambda is represented by a singleton implementing Runnable – <clinit>(), <init>(), run() methods are declared
24. SAM conversions: inline
25. SAM conversions: crossinline – class representing lambda implements Runnable – gets instantiated every time – <init>(), run() methods are declared
26. SAM conversions: noinline – class representing lambda is a singleton implementing Function0 – <clinit>, <init>, void invoke(), synthetic bridge Object invoke() methods are declared – Function0 is not Runnable, an adapter/proxy gets instantiated every time – <init>(Function0) and run() methods are declared
27. There are many ways to use enums...
28. SomeEnum.values() defensive copying
29. SomeEnum.values() replacement copy one time
30. Default LinkedHashMap vs. EnumMap much faster
31. Inline functions with default parameter values inlining of them is free
32. Private access between classes
33. Data class methods count per class: <init>(primary ctor args) <init>(no-arg) <init>(primary ctor params, bitmask, DefaultConstructorMarker ) toString, hashCode, equals copy & copy$default per property: getter & componentN setter if var
34. Data class methods count per class: <init>(primary ctor args) <init>(no-arg) <init>(primary ctor params, bitmask, DefaultConstructorMarker ) toString, hashCode, equals copy & copy$default per property: getter & componentN setter if var
35. See also • Anko, a library for Android development in Kotlin: github.com/Kotlin/anko • Enum problem (ru): javanese.online/статьи/enum_недоработка/ • enumMapOf(), enumSetOf() Gist: goo.gl/cS6tfR • arrayMapOf(), sparseArrayOf(), arraySetOf()… no library yet! • Set<Long> replacement if you ever need it: github.com/Miha-x64/Blitz/ • Exploring Java’s Hidden Costs by Jake Wharton jakewharton.com/exploring-java-hidden-costs/ javanese.online/статьи/exploring_java_hidden_costs/ • Eliminating Code Overhead by Jake Wharton jakewharton.com/eliminating-code-overhead/
36. Thanks to • JetBrains, Oracle, Google • GDG • Fira Code • LibreOffice • github.com/amaembo/screenshoter
37. Questions? • @Harmonizr at t.me/kotlin_lang • @miha-x64 at kotlinlang.slack.com, gdgspb.slack.com, androidrus.slack.com • twitter.com/miha_x64