[jdk25] RFR: 8352075: Perf regression accessing fields

[Aleksey Shipilev]

On Thu, 19 Jun 2025 10:02:45 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Thank you for the backport! @shipilev indicated that the backport to 21 should wait a bit, could you clarify when should I file that (e.g. end of July, ...)?
>
>> @shipilev indicated that the backport to 21 should wait a bit, could you clarify when should I file that (e.g. end of July, ...)?
> 
> I would say for the fairly big change like this, we want to wait until JDK 25 GA (that would pass the all-tests-run). It would be too late for Oct 2025 release, though. So realistically, this would target January 2026 release. You can pull this patch to your downstream JDK 21 to see if there are any troubles ahead of this path, this will also soothe 21u maintainer concerns, I think.

> So @shipilev, JDK 25 is in rampdown phase 1. Rampdown phase 2 starts 7/17. It's a big change for JDK 25. My sense of the risk is that it's not high. If it's checked in now, I think it'll get more testing than if it gets backported to a 25.01 release. I'll discuss it with people here. I think for JDK 21, we should wait for more testing to be run after 25 GA.

Yeah, I am on the fence for JDK 25, can take it both ways. If it is to land in JDK 25u anyway, there is some benefit for doing it in GA for more testing. At the same time, JDK 26 is already testing it, so there is no particular need to risk JDK 25 stability, and we can just capitalize on JDK 26 testing for JDK 25u backport.

For JDK 21u, it definitely needs to be released in JDK 25 first.

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PR Comment: https://git.openjdk.org/jdk/pull/25877#issuecomment-2995450240