# Coroutines: Support class reloading used by tools like Play framework and SBT **URL:** \ **Category:** Support\ **Created:** [September 20, 2017, 6:24am UTC](https://discuss.kotlinlang.org/t/coroutines-support-class-reloading-used-by-tools-like-play-framework-and-sbt/4653 "2017-09-20T06:24:24Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![youhansr](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/youhansr/32/4052_2.png) [@youhansr](https://discuss.kotlinlang.org/u/youhansr)\ **Post date:** [September 20, 2017, 6:24am UTC](https://discuss.kotlinlang.org/t/coroutines-support-class-reloading-used-by-tools-like-play-framework-and-sbt/4653/1 "2017-09-20T06:24:24Z")
Currently, Play framework (Java version) uses SBT to reload classes on their change by compiling changed classes and restarting class loaders of running app. Everything was ok until I added kotlin coroutines to a controller and then when developing on that controller, every time I change the code, I must restart server which takes very long time. Is there any way to work around this? ---
**Author:** ![elizarov](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/elizarov/32/2164_2.png) [@elizarov](https://discuss.kotlinlang.org/u/elizarov)\ **Post date:** [September 22, 2017, 9:04am UTC](https://discuss.kotlinlang.org/t/coroutines-support-class-reloading-used-by-tools-like-play-framework-and-sbt/4653/2 "2017-09-22T09:04:27Z")
Can you provide a link to some self-contained project that reproduces this problem? ---
**Author:** ![kirillkh](https://avatars.discourse-cdn.com/v4/letter/k/bbce88/32.png) [@kirillkh](https://discuss.kotlinlang.org/u/kirillkh)\ **Post date:** [September 24, 2017, 9:28am UTC](https://discuss.kotlinlang.org/t/coroutines-support-class-reloading-used-by-tools-like-play-framework-and-sbt/4653/3 "2017-09-24T09:28:20Z")
FWIW, I’m experiencing a lot of hot reloading problems with Android since introducing coroutines. Basically, I had to turn the feature off. Right now it won’t even compile: ```auto Error:Execution failed for task ':app:transformClassesWithDexBuilderForDebug'. > com.android.build.api.transform.TransformException: org.gradle.tooling.BuildException: com.android.dx.cf.code.SimException: local 0007: invalid ``` ---
**Author:** ![elizarov](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/elizarov/32/2164_2.png) [@elizarov](https://discuss.kotlinlang.org/u/elizarov)\ **Post date:** [September 25, 2017, 7:09am UTC](https://discuss.kotlinlang.org/t/coroutines-support-class-reloading-used-by-tools-like-play-framework-and-sbt/4653/4 "2017-09-25T07:09:50Z")
Can you elaborate on the problem? Can you reproduce with a self-contained example or post your project? ---
**Author:** ![kirillkh](https://avatars.discourse-cdn.com/v4/letter/k/bbce88/32.png) [@kirillkh](https://discuss.kotlinlang.org/u/kirillkh)\ **Post date:** [September 25, 2017, 12:02pm UTC](https://discuss.kotlinlang.org/t/coroutines-support-class-reloading-used-by-tools-like-play-framework-and-sbt/4653/5 "2017-09-25T12:02:33Z")
I’m using Android Studio 3.0 beta 6 with Kotlin 1.1.4-2. The project uses Anko and this library: [GitHub - lightningkite/kotlin-anko](https://github.com/lightningkite/kotlin-anko) Steps to reproduce: 1. enable Instant Run in Settings 2. build the project 3. run the project =\> exception as above. Stack trace from the Gradle console: ```auto :app:transformClassesWithDexBuilderForDebug Error while processing com\lightningkite\kotlin\anko\HintSpinner.class com.android.dx.cf.code.SimException: local 0007: invalid at com.android.dx.cf.code.OneLocalsArray.throwSimException(OneLocalsArray.java:243) at com.android.dx.cf.code.OneLocalsArray.get(OneLocalsArray.java:155) at com.android.dx.cf.code.BaseMachine.localArg(BaseMachine.java:211) at com.android.dx.cf.code.Simulator$SimVisitor.visitLocal(Simulator.java:604) at com.android.dx.cf.code.BytecodeArray.parseInstruction(BytecodeArray.java:368) at com.android.dx.cf.code.Simulator.simulate(Simulator.java:103) at com.android.dx.cf.code.Ropper.processBlock(Ropper.java:790) at com.android.dx.cf.code.Ropper.doit(Ropper.java:745) at com.android.dx.cf.code.Ropper.convert(Ropper.java:350) at com.android.dx.dex.cf.CfTranslator.processMethods(CfTranslator.java:309) at com.android.dx.dex.cf.CfTranslator.translate0(CfTranslator.java:150) at com.android.dx.dex.cf.CfTranslator.translate(CfTranslator.java:102) at com.android.builder.dexing.DxDexArchiveBuilder.dex(DxDexArchiveBuilder.java:115) at com.android.builder.dexing.DxDexArchiveBuilder.convert(DxDexArchiveBuilder.java:85) at com.android.build.gradle.internal.transforms.DexArchiveBuilderTransform$DexConversionWorkAction.run(DexArchiveBuilderTransform.java:433) at com.android.build.gradle.internal.transforms.DexArchiveBuilderTransform.lambda$convertToDexArchive$1(DexArchiveBuilderTransform.java:519) at java.util.concurrent.ForkJoinTask$AdaptedCallable.exec(ForkJoinTask.java:1424) at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289) at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056) at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692) at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157) ``` Looking at the stack trace, I’m not sure it’s even related to coroutines, though… ---
**Author:** ![elizarov](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/elizarov/32/2164_2.png) [@elizarov](https://discuss.kotlinlang.org/u/elizarov)\ **Post date:** [September 25, 2017, 12:49pm UTC](https://discuss.kotlinlang.org/t/coroutines-support-class-reloading-used-by-tools-like-play-framework-and-sbt/4653/6 "2017-09-25T12:49:56Z")
Looking at the stack trace it does not even seem to be related to Kotlin, but looks like a bug in a beta version of Android toolchain. I would highly recommend reporting it to Google Android team. ---
**Author:** ![kirillkh](https://avatars.discourse-cdn.com/v4/letter/k/bbce88/32.png) [@kirillkh](https://discuss.kotlinlang.org/u/kirillkh)\ **Post date:** [September 25, 2017, 1:01pm UTC](https://discuss.kotlinlang.org/t/coroutines-support-class-reloading-used-by-tools-like-play-framework-and-sbt/4653/7 "2017-09-25T13:01:33Z")
I did have problems with coroutines before I started using this library, though. Pretty sure it was related to using Anko’s onClick. “Apply changes” would result in runtime exception after I did something with the GUI.