We're close to the runtime limit for box tests on GitHub (6 hours, we're at ~5). Worth considering parallelizing them - I'm thinking about it already. AFAIK, GitHub Actions allow parallel execution on multiple machines, the main difficulty will be telling Gradle/JUnit to run a specific subset (map), and then join the results (reduce).

That's strange why they are made bigger in 3 times after my last PR... Will be tricky to split them... I had some ideas regarding the performance of tests themselves (1, 2). I can check the next week or you can do it if you want:

I think the more IR stuff we translate, the more time it takes for the compiler to produce the output. But true, this increase is suspicious. Whoever has an opportunity to work on it, let's check it out :)

How much time do box tests take on your machine, by the way? After we've updated to Kotlin 1.5.21 and I've switched to 24-threaded CPU, they only take 8-10 minutes on mine 😅

Regarding StringBuilder, Kotlin's string interpolation uses StringBuilder under the hood

Kotlin's string interpolation uses StringBuilder under the hood

I doubt it works outside of a single function... Inside a single one – definitely of course

I haven't measured, but I think around 1-2 hours. For sure not 4 :D. Will check it next time

Wow, that's a lot. Do you use ramdisks?

I once tried to use them, but then the tests didn't work at all. I didn't have time to investigate back then.

We can also try enabling ramdisks for GH Actions

Good idea, also thought about it

We can consider it too 😉 The problem is I don't run Linux usually, only for Kotlin

No worries, I meant it as a joke only :D we'll figure something out so that I won't have to ask you to run your machine so that my PR gets validated ;)

I hope 😉

I don't have any experience with GH actions but I'm fairly knowledgeable of GitLab CI, I have no idea if that's useful for you, but if it is please ping me, I'd love to help a bit on this project

Are you willing to learn GitHub Actions? Any help to optimize the CI would be great

I’d suggest profile tests first to understand which parts are heavier in your case

@bashor, it seems profiling doesn't work for me for test tasks. I've mentioned it here: https://kotlinlang.slack.com/archives/C0289CS37AS/p1627654423005300 Does it work for you? I've also asked IntelliJ folks about it and already received an answer, will check on Friday

Yes, it worked for me, I think even from gradle in last few major versions.

JFTR, I was asked to file a ticket by IntelliJ folks about unavailable profiler: https://youtrack.jetbrains.com/issue/IDEA-275500

🤷‍♂️ it works for me