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Comment by BoardsOfCanada | Hacker News Reader

I've ported a lot of services from kotlin to rust. In my experience the kotlin code is about half the size of rust, and has about 200 mb + 2*x the memory overhead. Kotlin code probably takes about half of the time (or less) to write compared to rust as well, but you're not quite as sure that is it bug free as the rust code once it's done.

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That's a great point and I'm not sure why the memory usage/performance didn't come to mind when writing this.

It's probably because, like most JVM related things, it fits into the "good enough" bracket. Most things running in the JVM are definitely not on the forefront of either CPU or memory performance.

I haven't done personal estimates, but your 200 mb + 2*x estimate feels in line to what I'd expect when compared to "memory-tight" languages.

I agree and I'm not sure what language I would choose myself if it was up to me. In reality, we deployed to kubernetes with redundant instances and memory usage was the limiting factor with kotlin and it would not have been with rust.

Im curious :) Why did you port the services from Kotlin to rust? Can you elaborate a bit on the reasons for the rewrite?

I just like programming and I ported what I wrote at work to rust in my spare time. Basically I was thinking about if rust would be viable at work and in my spare time I tested the hypothesis.

An important distinction is also whether you were using Kotlin-JVM or Kotlin-native. I'd imagine the native version doesn't have the same memory impacts. (But you also don't get the JVM advantages).

While I didn't try kotlin native, I did try porting the micro service from spring boot to micronaut + graalvm native and the memory usage was pretty much identical to spring boot.

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