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Scala 3 slowed us down?

(kmaliszewski9.github.io)
261 points kmaliszewski | 1 comments | 07 Dec 25 15:08 UTC | HN request time: 0s | source
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jiehong ◴[07 Dec 25 18:17 UTC] No.46183745[source]▶
> After upgrading the library, performance and CPU characteristics on Scala 3 became indistinguishable from Scala 2.13.

Checking the bug mentioned, it was fixed in 2022.

So, I’m wondering how one would upgrade to scala 3, while keeping old version of libraries?

Keeping updated libraries is a good practice (even mandatory if you get audits like PCI-DSS).

That part puzzled me more than the rest.

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mystifyingpoi ◴[07 Dec 25 19:22 UTC] No.46184274[source]▶
I'm confused as well, because he wrote

> I did it as usual - updating dependencies

but later

> After upgrading the library, performance and CPU characteristics on Scala 3 became indistinguishable from Scala 2.13.

So... he didn't upgrade everything at first? Which IMO makes sense, generally you'd want to upgrade as little as possible with small steps. He just got unlucky.

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1. gavinray ◴[07 Dec 25 19:40 UTC] No.46184434[source]▶
It would have been a transitive dependency based on the comments about the library being "transparent" and the author unaware it was even used.

Pinning specific versions of transitive deps is fairly common in large JVM projects due to either security reasons or ABI compatibility or bugs