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1# kotlinx.coroutines
2
3[![Kotlin Stable](https://kotl.in/badges/stable.svg)](https://kotlinlang.org/docs/components-stability.html)
4[![JetBrains official project](https://jb.gg/badges/official.svg)](https://confluence.jetbrains.com/display/ALL/JetBrains+on+GitHub)
5[![GitHub license](https://img.shields.io/badge/license-Apache%20License%202.0-blue.svg?style=flat)](https://www.apache.org/licenses/LICENSE-2.0)
6[![Download](https://img.shields.io/maven-central/v/org.jetbrains.kotlinx/kotlinx-coroutines-core/1.10.1)](https://central.sonatype.com/artifact/org.jetbrains.kotlinx/kotlinx-coroutines-core/1.10.1)
7[![Kotlin](https://img.shields.io/badge/kotlin-2.0.0-blue.svg?logo=kotlin)](http://kotlinlang.org)
8[![KDoc link](https://img.shields.io/badge/API_reference-KDoc-blue)](https://kotlinlang.org/api/kotlinx.coroutines/)
9[![Slack channel](https://img.shields.io/badge/chat-slack-green.svg?logo=slack)](https://kotlinlang.slack.com/messages/coroutines/)
10
11Library support for Kotlin coroutines with [multiplatform](#multiplatform) support.
12This is a companion version for the Kotlin `2.0.0` release.
13
14```kotlin
15suspend fun main() = coroutineScope {
16    launch {
17       delay(1000)
18       println("Kotlin Coroutines World!")
19    }
20    println("Hello")
21}
22```
23
24> Play with coroutines online [here](https://pl.kotl.in/9zva88r7S)
25
26## Modules
27
28* [core](kotlinx-coroutines-core/README.md) — common coroutines across all platforms:
29  * [launch] and [async] coroutine builders returning [Job] and [Deferred] light-weight futures with cancellation support;
30  * [Dispatchers] object with [Main][Dispatchers.Main] dispatcher for Android/Swing/JavaFx (which require the corresponding artifacts in runtime) and Darwin (included out of the box), and [Default][Dispatchers.Default] dispatcher for background coroutines;
31  * [delay] and [yield] top-level suspending functions;
32  * [Flow] — cold asynchronous stream with [flow][_flow] builder and comprehensive operator set ([filter], [map], etc);
33  * [Channel], [Mutex], and [Semaphore] communication and synchronization primitives;
34  * [coroutineScope][_coroutineScope], [supervisorScope][_supervisorScope], [withContext], and [withTimeout] scope builders;
35  * [MainScope()] for Android and UI applications;
36  * [SupervisorJob()] and [CoroutineExceptionHandler] for supervision of coroutines hierarchies;
37  * [select] expression support and more.
38* [core/jvm](kotlinx-coroutines-core/jvm/) — additional core features available on Kotlin/JVM:
39  * [Dispatchers.IO] dispatcher for blocking coroutines;
40  * [Executor.asCoroutineDispatcher][asCoroutineDispatcher] extension, custom thread pools, and more;
41  * Integrations with `CompletableFuture` and JVM-specific extensions.
42* [core/js](kotlinx-coroutines-core/js/) — additional core features available on Kotlin/JS:
43  * Integration with `Promise` via [Promise.await] and [promise] builder;
44  * Integration with `Window` via [Window.asCoroutineDispatcher], etc.
45* [test](kotlinx-coroutines-test/README.md) — test utilities for coroutines:
46  * [Dispatchers.setMain] to override [Dispatchers.Main] in tests;
47  * [runTest] and [TestScope] to test suspending functions and coroutines.
48* [debug](kotlinx-coroutines-debug/README.md) — debug utilities for coroutines:
49  * [DebugProbes] API to probe, keep track of, print and dump active coroutines;
50  * [CoroutinesTimeout] test rule to automatically dump coroutines on test timeout.
51  * Automatic integration with [BlockHound](https://github.com/reactor/BlockHound).
52* [reactive](reactive/README.md) — modules that provide builders and iteration support for various reactive streams libraries:
53  * Reactive Streams ([Publisher.collect], [Publisher.awaitSingle], [kotlinx.coroutines.reactive.publish], etc),
54  * Flow (JDK 9) (the same interface as for Reactive Streams),
55  * RxJava 2.x ([rxFlowable], [rxSingle], etc), and
56  * RxJava 3.x ([rxFlowable], [rxSingle], etc), and
57  * Project Reactor ([flux], [mono], etc).
58* [ui](ui/README.md) — modules that provide the [Main][Dispatchers.Main] dispatcher for various single-threaded UI libraries:
59  * Android, JavaFX, and Swing.
60* [integration](integration/README.md) — modules that provide integration with various asynchronous callback- and future-based libraries:
61  * Guava [ListenableFuture.await], and Google Play Services [Task.await];
62  * SLF4J MDC integration via [MDCContext].
63
64## Documentation
65
66* Presentations and videos:
67  * [Kotlin Coroutines in Practice](https://www.youtube.com/watch?v=a3agLJQ6vt8) (Roman Elizarov at KotlinConf 2018, [slides](https://www.slideshare.net/elizarov/kotlin-coroutines-in-practice-kotlinconf-2018))
68  * [Deep Dive into Coroutines](https://www.youtube.com/watch?v=YrrUCSi72E8) (Roman Elizarov at KotlinConf 2017, [slides](https://www.slideshare.net/elizarov/deep-dive-into-coroutines-on-jvm-kotlinconf-2017))
69  * [History of Structured Concurrency in Coroutines](https://www.youtube.com/watch?v=Mj5P47F6nJg) (Roman Elizarov at Hydra 2019, [slides](https://speakerdeck.com/elizarov/structured-concurrency))
70* Guides and manuals:
71  * [Guide to kotlinx.coroutines by example](https://kotlinlang.org/docs/coroutines-guide.html) (**read it first**)
72  * [Guide to UI programming with coroutines](ui/coroutines-guide-ui.md)
73  * [Debugging capabilities in kotlinx.coroutines](docs/topics/debugging.md)
74* [Compatibility policy and experimental annotations](docs/topics/compatibility.md)
75* [Change log for kotlinx.coroutines](CHANGES.md)
76* [Coroutines design document (KEEP)](https://github.com/Kotlin/KEEP/blob/master/proposals/coroutines.md)
77* [Full kotlinx.coroutines API reference](https://kotlinlang.org/api/kotlinx.coroutines/)
78
79## Using in your projects
80
81### Maven
82
83Add dependencies (you can also add other modules that you need):
84
85```xml
86<dependency>
87    <groupId>org.jetbrains.kotlinx</groupId>
88    <artifactId>kotlinx-coroutines-core</artifactId>
89    <version>1.10.1</version>
90</dependency>
91```
92
93And make sure that you use the latest Kotlin version:
94
95```xml
96<properties>
97    <kotlin.version>2.0.0</kotlin.version>
98</properties>
99```
100
101### Gradle
102
103Add dependencies (you can also add other modules that you need):
104
105```kotlin
106dependencies {
107    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.10.1")
108}
109```
110
111And make sure that you use the latest Kotlin version:
112
113```kotlin
114plugins {
115    // For build.gradle.kts (Kotlin DSL)
116    kotlin("jvm") version "2.0.0"
117
118    // For build.gradle (Groovy DSL)
119    id "org.jetbrains.kotlin.jvm" version "2.0.0"
120}
121```
122
123Make sure that you have `mavenCentral()` in the list of repositories:
124
125```kotlin
126repositories {
127    mavenCentral()
128}
129```
130
131### Android
132
133Add [`kotlinx-coroutines-android`](ui/kotlinx-coroutines-android)
134module as a dependency when using `kotlinx.coroutines` on Android:
135
136```kotlin
137implementation("org.jetbrains.kotlinx:kotlinx-coroutines-android:1.10.1")
138```
139
140This gives you access to the Android [Dispatchers.Main]
141coroutine dispatcher and also makes sure that in case of a crashed coroutine with an unhandled exception that
142this exception is logged before crashing the Android application, similarly to the way uncaught exceptions in
143threads are handled by the Android runtime.
144
145#### R8 and ProGuard
146
147R8 and ProGuard rules are bundled into the [`kotlinx-coroutines-android`](ui/kotlinx-coroutines-android) module.
148For more details see ["Optimization" section for Android](ui/kotlinx-coroutines-android/README.md#optimization).
149
150#### Avoiding including the debug infrastructure in the resulting APK
151
152The `kotlinx-coroutines-core` artifact contains a resource file that is not required for the coroutines to operate
153normally and is only used by the debugger. To exclude it at no loss of functionality, add the following snippet to the
154`android` block in your Gradle file for the application subproject:
155
156```kotlin
157packagingOptions {
158    resources.excludes += "DebugProbesKt.bin"
159}
160```
161
162### Multiplatform
163
164Core modules of `kotlinx.coroutines` are also available for
165[Kotlin/JS](https://kotlinlang.org/docs/reference/js-overview.html) and [Kotlin/Native](https://kotlinlang.org/docs/reference/native-overview.html).
166
167In common code that should get compiled for different platforms, you can add a dependency to `kotlinx-coroutines-core` right to the `commonMain` source set:
168
169```kotlin
170commonMain {
171    dependencies {
172        implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.10.1")
173    }
174}
175```
176
177Platform-specific dependencies are recommended to be used only for non-multiplatform projects that are compiled only for target platform.
178
179#### JS
180
181Kotlin/JS version of `kotlinx.coroutines` is published as
182[`kotlinx-coroutines-core-js`](https://central.sonatype.com/artifact/org.jetbrains.kotlinx/kotlinx-coroutines-core-js/1.10.1)
183(follow the link to get the dependency declaration snippet).
184
185#### Native
186
187Kotlin/Native version of `kotlinx.coroutines` is published as
188[`kotlinx-coroutines-core-$platform`](https://central.sonatype.com/search?q=kotlinx-coroutines-core&namespace=org.jetbrains.kotlinx) where `$platform` is
189the target Kotlin/Native platform.
190Targets are provided in accordance with [official K/N target support](https://kotlinlang.org/docs/native-target-support.html).
191## Building and Contributing
192
193See [Contributing Guidelines](CONTRIBUTING.md).
194
195<!--- MODULE kotlinx-coroutines-core -->
196<!--- INDEX kotlinx.coroutines -->
197
198[launch]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/launch.html
199[async]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/async.html
200[Job]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-job/index.html
201[Deferred]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-deferred/index.html
202[Dispatchers]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-dispatchers/index.html
203[Dispatchers.Main]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-dispatchers/-main.html
204[Dispatchers.Default]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-dispatchers/-default.html
205[delay]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/delay.html
206[yield]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/yield.html
207[_coroutineScope]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/coroutine-scope.html
208[_supervisorScope]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/supervisor-scope.html
209[withContext]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/with-context.html
210[withTimeout]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/with-timeout.html
211[MainScope()]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-main-scope.html
212[SupervisorJob()]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-supervisor-job.html
213[CoroutineExceptionHandler]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-coroutine-exception-handler/index.html
214[Dispatchers.IO]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-i-o.html
215[asCoroutineDispatcher]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/as-coroutine-dispatcher.html
216[Promise.await]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/await.html
217[promise]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/[js]promise.html
218[Window.asCoroutineDispatcher]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/as-coroutine-dispatcher.html
219
220<!--- INDEX kotlinx.coroutines.flow -->
221
222[Flow]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.flow/-flow/index.html
223[_flow]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.flow/flow.html
224[filter]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.flow/filter.html
225[map]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.flow/map.html
226
227<!--- INDEX kotlinx.coroutines.channels -->
228
229[Channel]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.channels/-channel/index.html
230
231<!--- INDEX kotlinx.coroutines.selects -->
232
233[select]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.selects/select.html
234
235<!--- INDEX kotlinx.coroutines.sync -->
236
237[Mutex]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.sync/-mutex/index.html
238[Semaphore]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.sync/-semaphore/index.html
239
240<!--- MODULE kotlinx-coroutines-test -->
241<!--- INDEX kotlinx.coroutines.test -->
242
243[Dispatchers.setMain]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-test/kotlinx.coroutines.test/set-main.html
244[runTest]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-test/kotlinx.coroutines.test/run-test.html
245[TestScope]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-test/kotlinx.coroutines.test/-test-scope/index.html
246
247<!--- MODULE kotlinx-coroutines-debug -->
248<!--- INDEX kotlinx.coroutines.debug -->
249
250[DebugProbes]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-debug/kotlinx.coroutines.debug/-debug-probes/index.html
251
252<!--- INDEX kotlinx.coroutines.debug.junit4 -->
253
254[CoroutinesTimeout]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-debug/kotlinx.coroutines.debug.junit4/-coroutines-timeout/index.html
255
256<!--- MODULE kotlinx-coroutines-slf4j -->
257<!--- INDEX kotlinx.coroutines.slf4j -->
258
259[MDCContext]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-slf4j/kotlinx.coroutines.slf4j/-m-d-c-context/index.html
260
261<!--- MODULE kotlinx-coroutines-jdk8 -->
262<!--- INDEX kotlinx.coroutines.future -->
263<!--- MODULE kotlinx-coroutines-guava -->
264<!--- INDEX kotlinx.coroutines.guava -->
265
266[ListenableFuture.await]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-guava/kotlinx.coroutines.guava/await.html
267
268<!--- MODULE kotlinx-coroutines-play-services -->
269<!--- INDEX kotlinx.coroutines.tasks -->
270
271[Task.await]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-play-services/kotlinx.coroutines.tasks/await.html
272
273<!--- MODULE kotlinx-coroutines-reactive -->
274<!--- INDEX kotlinx.coroutines.reactive -->
275
276[Publisher.collect]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-reactive/kotlinx.coroutines.reactive/collect.html
277[Publisher.awaitSingle]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-reactive/kotlinx.coroutines.reactive/await-single.html
278[kotlinx.coroutines.reactive.publish]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-reactive/kotlinx.coroutines.reactive/publish.html
279
280<!--- MODULE kotlinx-coroutines-rx2 -->
281<!--- INDEX kotlinx.coroutines.rx2 -->
282
283[rxFlowable]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-rx2/kotlinx.coroutines.rx2/rx-flowable.html
284[rxSingle]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-rx2/kotlinx.coroutines.rx2/rx-single.html
285
286<!--- MODULE kotlinx-coroutines-rx2 -->
287<!--- INDEX kotlinx.coroutines.rx2 -->
288<!--- MODULE kotlinx-coroutines-reactor -->
289<!--- INDEX kotlinx.coroutines.reactor -->
290
291[flux]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-reactor/kotlinx.coroutines.reactor/flux.html
292[mono]: https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-reactor/kotlinx.coroutines.reactor/mono.html
293
294<!--- END -->
295