A general question, what Java/JVM version should you run on if you are running a server in purely kotlin? I am currently on

kotlinOptions.jvmTarget = "1.8"

and that feels a bit ancient, I have not really followed what has happened to to jvm since the Stream API basically. What is a sensible version to run the latest kotlin versions on now? Are there any performance improvements for kotlin?

Note that the steam api is totally unrelated to the JVM, that's purely a java thing.

Ah okay, I know they are unrelated but I thought the introduction of such a big shift required some new JVM instructions

AFAIK Kotlin doesn't target anything above 1.8 yet, but you can and probably should still run on the newest JVM possible for performance and bug fixes.

Java 8 was maybe a much bigger release on the Java side then on the JVM side then maybe

if you use Kotlin version >=1.3.30 you can set the jvmTarget to newer versions 9-12. There are no performance improvements yet, but there will be, so that’s where i’d start. https://blog.jetbrains.com/kotlin/2019/04/kotlin-1-3-30-released/#more-6991

Alright, great 🙂 upgrading the JVM always felt like packing up and moving to a new universe, have a hard time getting used to the JVMs new release schedule

There are special JVM instructions, but they're not necessary. There's an issue about the Kotlin compiler actually using them, can't find it easily on mobile though.