Kotlin: How can I avoid autoboxing (garbage) in delegated properties?

Question

In my software, I have some various values which use property delegation.

This is a simple similar example showing what I do:

class ExampleDelegate<T>(val value: T) {

    operator fun getValue(thisRef: Any?, property: KProperty<*>) = value

}

val example by ExampleDelegate(1000) // number larger than 127 (no box cache)

What I've noticed, however, is that referring to this value seems to create an autoboxed object (java.lang.Integer) on EVERY reference. Because the value must be referenced potentially millions or times per second, this results in massive garbage creation for my software; heavy stress is put on the garbage collector.

Is there a way to avoid the overhead? If not directly, are there any clever ways to "emulate" property delegation that are performant?

Submitted a bug report on YouTrack: https://youtrack.jetbrains.com/issue/KT-13606

Answer 1

As discussed in the bug report, your app generates garbage because your property delegate is generic, and therefore requires boxing of values. If you use a non-generic property delegate with a primitive type, no boxing happens.