introduction to coroutines
play

Introduction to Coroutines Roman Elizarov elizarov at JetBrains - PowerPoint PPT Presentation

Sep 04, 2022 •361 likes •1.83k views

Introduction to Coroutines Roman Elizarov elizarov at JetBrains Asynchronous programming How do we write code that waits for something most of the time? A toy problem fun requestToken(): Token { 1 Kotlin // makes request for a token &

  1. Higher-order functions val post = retryIO { createPost (token, item) } suspending lambda suspend fun <T> retryIO(block: suspend () -> T): T { var curDelay = 1000L // start with 1 sec while ( true ) { try { return block() } catch (e: IOException) { e.printStackTrace() // log the error } delay (curDelay) curDelay = (curDelay * 2). coerceAtMost (60000L) } }

  2. Higher-order functions val post = retryIO { createPost (token, item) } suspend fun <T> retryIO(block: suspend () -> T): T { var curDelay = 1000L // start with 1 sec while ( true ) { try { return block() } catch (e: IOException) { e.printStackTrace() // log the error } delay (curDelay) curDelay = (curDelay * 2). coerceAtMost (60000L) } } Everything like in blocking code

  3. Higher-order functions val post = retryIO { createPost (token, item) } suspend fun <T> retryIO(block: suspend () -> T): T { var curDelay = 1000L // start with 1 sec while ( true ) { try { return block() } catch (e: IOException) { e.printStackTrace() // log the error } delay (curDelay) curDelay = (curDelay * 2). coerceAtMost (60000L) } }

  4. Coroutine builders

  5. Coroutines revisited suspend fun requestToken(): Token { … } suspend fun createPost(token: Token, item: Item): Post { … } fun processPost(post: Post) { … } suspend fun postItem(item: Item) { val token = requestToken () val post = createPost (token, item) processPost (post) }

  6. Coroutines revisited suspend fun requestToken(): Token { … } suspend fun createPost(token: Token, item: Item): Post { … } fun processPost(post: Post) { … } fun postItem(item: Item) { val token = requestToken () val post = createPost (token, item) processPost (post) }

  7. Coroutines revisited suspend fun requestToken(): Token { … } suspend fun createPost(token: Token, item: Item): Post { … } fun processPost(post: Post) { … } fun postItem(item: Item) { val token = requestToken () val post = createPost (token, item) processPost (post) } Error: Suspend function 'requestToken' should be called only from a coroutine or another suspend function

  8. Coroutines revisited suspend fun requestToken(): Token { … } suspend fun createPost(token: Token, item: Item): Post { … } fun processPost(post: Post) { … } Can suspend execution fun postItem(item: Item) { val token = requestToken () val post = createPost (token, item) processPost (post) }

  9. Coroutines revisited suspend fun requestToken(): Token { … } suspend fun createPost(token: Token, item: Item): Post { … } fun processPost(post: Post) { … } A regular function cannot Can suspend execution fun postItem(item: Item) { val token = requestToken () val post = createPost (token, item) processPost (post) }

  10. Coroutines revisited suspend fun requestToken(): Token { … } suspend fun createPost(token: Token, item: Item): Post { … } fun processPost(post: Post) { … } A regular function cannot Can suspend execution fun postItem(item: Item) { val token = requestToken () val post = createPost (token, item) processPost (post) } One cannot simply invoke a suspending function

  11. Launch coroutine builder fun postItem(item: Item) { launch { val token = requestToken () val post = createPost (token, item) processPost (post) } }

  12. Returns immediately, coroutine works in background thread pool fun postItem(item: Item) { launch { val token = requestToken () val post = createPost (token, item) processPost (post) } Fire and forget! }

  13. fun postItem(item: Item) { launch { val token = requestToken () val post = createPost (token, item) processPost (post) } }

  14. UI Context Just specify the context fun postItem(item: Item) { launch (UI) { val token = requestToken () val post = createPost (token, item) processPost (post) } }

  15. UI Context fun postItem(item: Item) { launch (UI) { val token = requestToken () val post = createPost (token, item) processPost (post) } } And it gets executed on UI thread

  16. Where’s the magic of launch?

  17. A regular function fun launch( context: CoroutineContext = DefaultDispatcher, block: suspend () -> Unit ): Job { … }

  18. fun launch( context: CoroutineContext = DefaultDispatcher, block: suspend () -> Unit ): Job { … } suspending lambda

  19. fun launch( context: CoroutineContext = DefaultDispatcher, block: suspend () -> Unit ): Job { … }

  20. async / await

  21. Kotlin-way suspend fun requestToken(): Token { … } suspend fun createPost(token: Token, item: Item): Post { … } fun processPost(post: Post) { … } suspend fun postItem(item: Item) { Kotlin val token = requestToken () val post = createPost (token, item) processPost (post) }

  22. Classic-way async Task<Token> requestToken() { … } async Task<Post> createPost(Token token, Item item) { … } void processPost(Post post) { … } C# approach to the same problem (also Python, TS, Dart, coming to JS) async Task postItem(Item item) { C# var token = await requestToken (); var post = await createPost (token, item); processPost (post); }

  23. Classic-way async Task<Token> requestToken() { … } async Task<Post> createPost(Token token, Item item) { … } void processPost(Post post) { … } mark with async async Task postItem(Item item) { C# var token = await requestToken (); var post = await createPost (token, item); processPost (post); }

  24. Classic-way async Task<Token> requestToken() { … } async Task<Post> createPost(Token token, Item item) { … } void processPost(Post post) { … } async Task postItem(Item item) { C# var token = await requestToken (); var post = await createPost (token, item); processPost (post); } use await to suspend

  25. Classic-way async Task<Token> requestToken() { … } async Task<Post> createPost(Token token, Item item) { … } void processPost(Post post) { … } returns a future async Task postItem(Item item) { C# var token = await requestToken (); var post = await createPost (token, item); processPost (post); }

  26. Why no await keyword in Kotlin? The problem with async requestToken () VALID –> produces Task<Token> C# concurrent behavior default VALID –> produces Token await requestToken () C# sequential behavior

  27. Kotlin suspending functions are designed to imitate sequential behavior by default Concurrency is hard Concurrency has to be explicit

  28. Kotlin approach to async Concurrency where you need it

  29. Use-case for async async Task<Image> loadImageAsync(String name) { … } C#

  30. Use-case for async async Task<Image> loadImageAsync(String name) { … } C# var promise1 = loadImageAsync(name1); Start multiple operations var promise2 = loadImageAsync(name2); concurrently

  31. Use-case for async async Task<Image> loadImageAsync(String name) { … } C# var promise1 = loadImageAsync(name1); var promise2 = loadImageAsync(name2); var image1 = await promise1; and then wait for them var image2 = await promise2;

  32. Use-case for async async Task<Image> loadImageAsync(String name) { … } C# var promise1 = loadImageAsync(name1); var promise2 = loadImageAsync(name2); var image1 = await promise1; var image2 = await promise2; var result = combineImages(image1, image2);

  33. Kotlin async function fun loadImageAsync(name: String): Deferred<Image> = Kotlin async { … }

  34. Kotlin async function A regular function fun loadImageAsync(name: String): Deferred<Image> = Kotlin async { … }

  35. Kotlin async function Kotlin’s future type fun loadImageAsync(name: String): Deferred<Image> = Kotlin async { … }

  36. Kotlin async function fun loadImageAsync(name: String): Deferred<Image> = Kotlin async { … } async coroutine builder

  37. Kotlin async function fun loadImageAsync(name: String): Deferred<Image> = Kotlin async { … } val deferred1 = loadImageAsync(name1) Start multiple operations val deferred2 = loadImageAsync(name2) concurrently

  38. Kotlin async function fun loadImageAsync(name: String): Deferred<Image> = Kotlin async { … } val deferred1 = loadImageAsync(name1) val deferred2 = loadImageAsync(name2) val image1 = deferred1.await() and then wait for them val image2 = deferred2.await() await function Suspends until deferred is complete

  39. Kotlin async function fun loadImageAsync(name: String): Deferred<Image> = Kotlin async { … } val deferred1 = loadImageAsync(name1) val deferred2 = loadImageAsync(name2) val image1 = deferred1.await() val image2 = deferred2.await() val result = combineImages(image1, image2)

  40. Using async function when needed Is defined as suspending function, not async suspend fun loadImage(name: String): Image { … }

  41. Using async function when needed suspend fun loadImage(name: String): Image { … } suspend fun loadAndCombine(name1: String, name2: String): Image { val deferred1 = async { loadImage (name1) } val deferred2 = async { loadImage (name2) } return combineImages (deferred1.await(), deferred2.await()) }

  42. Using async function when needed suspend fun loadImage(name: String): Image { … } suspend fun loadAndCombine(name1: String, name2: String): Image { val deferred1 = async { loadImage (name1) } val deferred2 = async { loadImage (name2) } return combineImages (deferred1.await(), deferred2.await()) }

  43. Using async function when needed suspend fun loadImage(name: String): Image { … } suspend fun loadAndCombine(name1: String, name2: String): Image { val deferred1 = async { loadImage (name1) } val deferred2 = async { loadImage (name2) } return combineImages (deferred1.await(), deferred2.await()) }

  44. Using async function when needed suspend fun loadImage(name: String): Image { … } suspend fun loadAndCombine(name1: String, name2: String): Image { val deferred1 = async { loadImage (name1) } val deferred2 = async { loadImage (name2) } return combineImages (deferred1.await(), deferred2.await()) }

  45. Kotlin approach to async requestToken () VALID –> produces Token Kotlin sequential behavior default VALID –> produces Deferred<Token> async { requestToken () } Kotlin concurrent behavior

  46. Coroutines

  47. What are coroutines conceptually?

  48. What are coroutines conceptually? Coroutines are like very light-weight threads

  49. Example fun main(args: Array<String>) = runBlocking <Unit> { val jobs = List (100_000) { launch { delay (1000L) print ( "." ) } } jobs. forEach { it .join() } }

Recommend

C++20 Coroutines Miosz Warzecha Introduction Coroutines allow you to suspend function

C++20 Coroutines Miosz Warzecha Introduction Coroutines allow you to suspend function

C++20 Coroutines Miosz Warzecha Introduction Coroutines allow you to suspend function execution and return the control of the execution back to the caller Which .then allows you to run an asynchronous piece of code in the same way as you

1.41k views • 58 slides
Coroutines Update Seva Tolstopyatov @qwwdfsad October 13, 2020 Coroutines debugging Coroutines

Coroutines Update Seva Tolstopyatov @qwwdfsad October 13, 2020 Coroutines debugging Coroutines

Kotlin 1.4 Online Event Coroutines Update Seva Tolstopyatov @qwwdfsad October 13, 2020 Coroutines debugging Coroutines debugging Coroutines debugging Coroutines debugging Coroutines debugging IDEA 2020.1 Coroutines debugging Debugging

737 views • 41 slides
Coroutines in Lua Coroutines An unconventional, but quite powerful control mechanism Well

Coroutines in Lua Coroutines An unconventional, but quite powerful control mechanism Well

Coroutines in Lua Coroutines An unconventional, but quite powerful control mechanism Well known as an abstract concept, but with several variations Variations with big differences 2 Kinds of Coroutines Symmetric or asymmetric

625 views • 20 slides
Kotlin Coroutines in Practice Roman Eliza zarov !&quot;#$%&amp;( )

Kotlin Coroutines in Practice Roman Eliza zarov !&quot;#$%&amp;( )

Kotlin Coroutines in Practice Roman Eliza zarov !&quot;#$%&amp;( ) )&amp;!&quot;#$%&amp;( Coroutines recap Coroutines are like light-weight threads suspend fun main() { val jobs = List (100_000) { GlobalScope. launch { delay (5000)

1.44k views • 128 slides
Introduction to C++ Coroutines JAMES MCNELLIS SENIOR SOFTWARE ENGINEER MICROSOFT VISUAL C++

Introduction to C++ Coroutines JAMES MCNELLIS SENIOR SOFTWARE ENGINEER MICROSOFT VISUAL C++

Introduction to C++ Coroutines JAMES MCNELLIS SENIOR SOFTWARE ENGINEER MICROSOFT VISUAL C++ Motivation WHY ADD COROUTINES AT ALL? int64_t tcp_reader(int64_t total) { std::array&lt;char, 4096&gt; buffer; tcp::connection the_connection =

1.62k views • 95 slides
Concurrency, Parallelism and Coroutines Anthony Williams Just Software Solutions Ltd

Concurrency, Parallelism and Coroutines Anthony Williams Just Software Solutions Ltd

Concurrency, Parallelism and Coroutines Anthony Williams Just Software Solutions Ltd https://www.justsoftwaresolutions.co.uk 29th April 2017 Concurrency, Parallelism and Coroutines Parallelism in C++17 The Coroutines TS The Concurrency TS

1k views • 66 slides
Lecture 25: Coroutines Marvin Zhang 08/03/2016 Announcements Roadmap Introduction Functions

Lecture 25: Coroutines Marvin Zhang 08/03/2016 Announcements Roadmap Introduction Functions

Lecture 25: Coroutines Marvin Zhang 08/03/2016 Announcements Roadmap Introduction Functions This week (Paradigms), the goals are: Data To study examples of paradigms that are very different from what we have seen so far

789 views • 17 slides
eventlet eventlet coroutines flexible efficient control flow greenlet non-blocking i/o

eventlet eventlet coroutines flexible efficient control flow greenlet non-blocking i/o

eventlet eventlet coroutines flexible efficient control flow greenlet non-blocking i/o efficient network i/o select/poll/epoll threads switch between async and sync queues/pipes coroutines main subroutine: subroutine(1, 2)

487 views • 23 slides
Common Lisp Native Coroutines (sort of. . . ahem. . . actually, no) Didier Verna April 4 2017

Common Lisp Native Coroutines (sort of. . . ahem. . . actually, no) Didier Verna April 4 2017

Common Lisp Native Coroutines (sort of. . . ahem. . . actually, no) Didier Verna April 4 2017 Coroutines Very old idea yield values without losing its state resume its computation later (yielding more values) transfer control

652 views • 11 slides
Demystifying Coroutines and Asynchronous Programming in Python Mariano Anaya @rmarianoa FOSDEM

Demystifying Coroutines and Asynchronous Programming in Python Mariano Anaya @rmarianoa FOSDEM

Demystifying Coroutines and Asynchronous Programming in Python Mariano Anaya @rmarianoa FOSDEM 2019 - Feb 03 History PEP-255: Simple generators PEP-342: Coroutines via enhanced generators PEP-380: Syntax for delegating to a

659 views • 42 slides
LLVM Coroutines Bringing resumable functions to LLVM LLVM Dev Meeting 2016 Gor Nishanov

LLVM Coroutines Bringing resumable functions to LLVM LLVM Dev Meeting 2016 Gor Nishanov

LLVM Coroutines Bringing resumable functions to LLVM LLVM Dev Meeting 2016 Gor Nishanov (@GorNishanov) 1 Microsoft Visual C++ Team Coroutines Subroutine A Coroutine C Subroutine A Subroutine B C start B start Introduced

1.31k views • 71 slides
Lua: language for the Web? @paulcuth ES6 ES2015 Generators Coroutines Spread operator

Lua: language for the Web? @paulcuth ES6 ES2015 Generators Coroutines Spread operator

Lua: language for the Web? @paulcuth ES6 ES2015 Generators Coroutines Spread operator table.unpack() 2003 http://www.katalog-telefonow-komorkowych.pl/files/mobily/st1/1111/800x600_pl_PL/1330689341-orange-spv-e200-1.jpg 2003

1.16k views • 41 slides
Asynchronous programming with Kotlin coroutines in Spring Konrad Kami ski Allegro.pl

Asynchronous programming with Kotlin coroutines in Spring Konrad Kami ski Allegro.pl

Asynchronous programming with Kotlin coroutines in Spring Konrad Kami ski Allegro.pl @GetMapping(&quot;/users/{userId}/products) fun getProducts(@PathVariable userId: String): List&lt;Product&gt; { if

689 views • 30 slides
Lock-free algorithms for Kotlin coroutines It is all about scalability Presented at SPTCC 2017

Lock-free algorithms for Kotlin coroutines It is all about scalability Presented at SPTCC 2017

Lock-free algorithms for Kotlin coroutines It is all about scalability Presented at SPTCC 2017 /Roman Elizarov @ JetBrains Speaker: Roman Elizarov 16+ years experience Previously developed high-perf trading software @ Devexperts

1.41k views • 127 slides
Deep dive into Coroutines on JVM Roman Elizarov elizarov at JetBrains There is no magic

Deep dive into Coroutines on JVM Roman Elizarov elizarov at JetBrains There is no magic

Deep dive into Coroutines on JVM Roman Elizarov elizarov at JetBrains There is no magic Continuation Passing Style (CPS) A toy problem fun postItem(item: Item) { val token = requestToken () val post = createPost (token, item) processPost

1.37k views • 107 slides
Monolingual probabilistic programming using generalized coroutines Oleg Kiselyov Chung-chieh

Monolingual probabilistic programming using generalized coroutines Oleg Kiselyov Chung-chieh

Monolingual probabilistic programming using generalized coroutines Oleg Kiselyov Chung-chieh Shan FNMOC Rutgers University oleg@pobox.com ccshan@cs.rutgers.edu 19 June 2009 This session . . . programming formalism 2/14 This talk . . .

587 views • 55 slides
ASYNCHRONOUS DATA STREAMS WITH KOTLIN FLOW ROMAN ELIZAROV @relizarov Copenhagen Copenhagen

ASYNCHRONOUS DATA STREAMS WITH KOTLIN FLOW ROMAN ELIZAROV @relizarov Copenhagen Copenhagen

ASYNCHRONOUS DATA STREAMS WITH KOTLIN FLOW ROMAN ELIZAROV @relizarov Copenhagen Copenhagen Denmark Denmark RECAP ON KOTLIN COROUTINES Kotlin Coroutines FTW Callback hell before fun requestTokenAsync(): Promise&lt;Token&gt; { } fun

1.98k views • 161 slides
Implementing Raft protocol by coroutines and Ktor Framework Andrii Rodionov @AndriiRodionov

Implementing Raft protocol by coroutines and Ktor Framework Andrii Rodionov @AndriiRodionov

Implementing Raft protocol by coroutines and Ktor Framework Andrii Rodionov @AndriiRodionov About me Devoxx Ukraine organizer KNight Kyiv co-organizer JUG UA Leader Kyiv Kotlin User Group Co-leader Devoxx Ukraine

495 views • 32 slides
Coroutines and Reactive Programming friends or foes? Konrad Kami ski Allegro.pl suspend

Coroutines and Reactive Programming friends or foes? Konrad Kami ski Allegro.pl suspend

Coroutines and Reactive Programming friends or foes? Konrad Kami ski Allegro.pl suspend fun getUser(userId: Int): User? fun getDefaultUserName(userId: Int): String val name = getUser (userId)?.name ?: getDefaultUserName (userId) println

841 views • 73 slides
INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION

INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION

TRAINING COURSE ON SOCIAL PROTECTION &amp; FORMALIZATION TRINIDAD AND TOBAGO MARCH 15, 2017 INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION Design of the NIS Assistance from the

547 views • 23 slides
Delimited Continuations The Bees Knees Quasiconf 2012 Andy Wingo A poll How many of you

Delimited Continuations The Bees Knees Quasiconf 2012 Andy Wingo A poll How many of you

Delimited Continuations The Bees Knees Quasiconf 2012 Andy Wingo A poll How many of you use call/cc and continuation objects in large programs? Do we really use it to implement coroutines and backtracking and threads and whatever?

659 views • 28 slides
A Look Into the Future Roman Elizarov October 12, 2020 @relizarov A bit of history Kotlin 1.0

A Look Into the Future Roman Elizarov October 12, 2020 @relizarov A bit of history Kotlin 1.0

Kotlin 1.4 Online Event A Look Into the Future Roman Elizarov October 12, 2020 @relizarov A bit of history Kotlin 1.0 2016 Posted on February 15, 2016 by Andrey Breslav Kotlin 1.1 Released with JavaScript Support, Coroutines and more

1.09k views • 70 slides
Closure conversion Compiling try, finally, dynamic-wind raise, guard let loop, for, while

Closure conversion Compiling try, finally, dynamic-wind raise, guard let loop, for, while

Closure conversion Compiling try, finally, dynamic-wind raise, guard let loop, for, while continue, break Call/cc, call/ec, return threads, coroutines Function calls closure objects (code ptr, environment) Closure conversion In

644 views • 17 slides
INTRODUCTION Introduction 2/42 INTRODUCTION Alternations I am giving bread to the

INTRODUCTION Introduction 2/42 INTRODUCTION Alternations I am giving bread to the

Patterns of variation in the expression of case and agreement Andrs Brny Leiden University Centre for Linguistics 9 November 2019, BaSIS Workshop a.barany@hum.leidenuniv.nl INTRODUCTION Introduction 2/42 INTRODUCTION

1.37k views • 42 slides

More recommend