9

I'm building an annotation processor, and I recently switched from using the default annotationProcessor type to kapt, using the kotlin-kapt plugin.

I was debugging my processor by using the command

./gradlew --no-daemon -Dorg.gradle.debug=true :app:clean :app:compileDebugJavaWithJavac

(full instructions here: https://stackoverflow.com/a/42488641/502463 )

And then running a Remote debugging configuration. When I used annotationProcessor, I could hit breakpoints, and debug fine. with kapt, my processor runs, but I can't debug it. No breakpoints are triggered.

My kotlin version is 1.1.2-3

M Dapp
  • 1,453
  • 16
  • 31

4 Answers4

11

You actually want to debug the Kotlin compiler daemon, not the Gradle daemon. Here is how you can pass the required JVM arguments:

./gradlew <tasks> -Dkotlin.daemon.jvm.options="-Xdebug,-Xrunjdwp:transport=dt_socket\,address=5005\,server=y\,suspend=n"
Jayson Minard
  • 84,842
  • 38
  • 184
  • 227
yanex
  • 1,101
  • 8
  • 10
  • do I need to make changes to the Remote configuration as well? – M Dapp May 22 '17 at 18:53
  • I tried : ./gradlew --no-daemon -Dorg.gradle.debug=true :app:clean :app:compileDebugKotlin -Dkotlin.daemon.jvm.options="-Xdebug,-Xrunjdwp:transport=dt_socket\,address=5005\,server=y\,suspend=n" With no changes in the IDE, but no luck... – M Dapp May 22 '17 at 18:57
  • Please restart both Kotlin and Gradle daemons. You can find all Java processes being executed using the `jps` command. Also make sure the debug port in daemon JVM options and IDEA is the same (5005). – yanex May 22 '17 at 19:34
  • I see now... you also have to wait to attach the debugger until the kotlin compiler daemon starts – M Dapp May 22 '17 at 20:18
  • the kaptDebugKotlin task seems to keep running regardless of whether I debug it or not. Is there any way to make it wait for the debugger connection? – M Dapp May 30 '17 at 20:57
  • 5
    I was also struggling to debug a non-android project, in IntelliJ Idea. A colleague suggested that kotlin might be running it's own daemon, which prevents attaching debug configuration at appropriate time. Running kotlin without daemon fixes issue: `./gradlew clean :sample:build --no-daemon -Dorg.gradle.debug=true -Dkotlin.compiler.execution.strategy="in-process" -Dkotlin.daemon.jvm.options="-Xdebug,-Xrunjdwp:transport=dt_socket\,address=5005\,server=y\,suspend=n"`. Run this in CLI, then attach remote debug config when you feel comfortable, and not during `app:kaptDebugKotlin` task or whatever – Den Drobiazko Dec 26 '17 at 15:59
  • @DenRimus you save my day! this should be an alternative answer as it covers non android projects – Juan Saravia Oct 27 '18 at 17:15
3

I just tried to debug a Kotlin annotation processor and found this post. You can tell the JVM to wait for the debugger by passing suspend=y

What I do now is starting the build from command line:

./gradlew --no-daemon clean build -Dkotlin.daemon.jvm.options="-Xdebug,-Xrunjdwp:transport=dt_socket\,address=5005\,server=y\,suspend=y"

and then attaching with Intellij via remote configuration.

Max Holtzberg
  • 31
  • 1
2

The other answer is generally correct, but I found https://medium.com/@daptronic/annotation-processing-with-kapt-and-gradle-237793f2be57 helpful for going into more detail.

You can run something like this 

./gradlew --no-daemon clean compileDebugKotlin -Dkotlin.daemon.jvm.options="-Xdebug,-Xrunjdwp:transport=dt_socket\,address=5005\,server=y\,suspend=n"

or if you want to run a specific module

./gradlew --no-daemon :modulename:clean :modulename:compileDebugKotlin -Dkotlin.daemon.jvm.options="-Xdebug,-Xrunjdwp:transport=dt_socket\,address=5005\,server=y\,suspend=n"

The tricky part

We actually need to wait for the Kotlin compilation task to begin before we attach the debugger, it doesn't pause and wait for you to attach the debugger like with java.

So you want to monitor your build and look for the task: :app:kaptDebugKotlin And when you see it, head immediately over to your IDE and hit debug on your Remote configuration. If you don’t attach in time, the task will just move on. You have a few seconds to figure it out, but it’s a bit of a race to get it all working.

This took me a frustratingly long time to figure out and get working. Now as soon as I run the command I just go to the IDE and mash the debugger button and I have had pretty good luck getting it to attach that way.

Zoe
  • 27,060
  • 21
  • 118
  • 148
konakid
  • 656
  • 5
  • 7
  • 1
    Hmmm... is this still working on the latest version of Android Studio/ Kotlin? I'm trying to follow this approach and I keep getting: - Unable to open debugger port (localhost:5005): java.net.BindException "Address already in use (Bind failed)" I have already called jps to check all the running processes and as far as I can tell there's none running. – cmota Jul 17 '19 at 14:18
  • As of kotlin 1.7.20 the other answers are no longer working for me, and the only approach I can get to work is to add the flags "-Dorg.gradle.debug=true -Dkotlin.compiler.execution.strategy=in-process" – konakid Nov 05 '22 at 19:19
2

Since Kotlin 1.2.60, kapt supports using the Gradle Worker API by including kapt.use.worker.api=true in your gradle.properties file.

The bonus side effect is that the kapt task is debuggable with the normal gradle debug arguments (./gradlew <task> -Dorg.gradle.debug=true --no-daemon) , and no specific kotlin args are needed.

David Liu
  • 9,426
  • 5
  • 40
  • 63