Considering raising the Java baseline to 25 for Micronaut 5

[sdelamo]

We are considering raising the Java baseline to Java 25 for Micronaut 5.

It will also mean raising the Kotlin version to 2.3.

Why? We use major version releases to raise the Java baseline, and as a result, take advantage of new language features such as Scoped values within the framework code.

Moreover, we are hitting some bugs that are only resolved in Java 22.

Cloud vendors have adopted 25 as well. For example, Lambda supports Java 25. Google Cloud recommends using 25.. Java 25 is supported in Amazon Elastic Beanstalk. Google Cloud Run supports 25 as a preview.

Azure functions seem to be still on 21, but we can assume 25 will be there by the time we release Micronaut 5.

I would like to get some feedback from the community about this decission.

[msgilligan]

I think this is a great idea if you can pull it off. Being able to rely on GraalVM 25+ and FFM (Panama) will be a huge benefit.

[leeturner]

I think this is a great idea

[donbeave]

It will be significant. I hope you all will use Java 25 as the baseline. I also believe it's better to always adopt the latest available JDK version with each new major release from Micronaut.

[viniciusxyz]

Since there are even bugs in the JDK, I consider it a good idea to have JDK 25 as a baseline, but I think it would be interesting to consider a few points:

• Having a version still in the 4.x line that fully supports JDK 25, so we can adapt in terms of pipelines, images, and other things before upgrading to version 5.x. This makes it easier because when the new version is ready, we will only have to worry about migrating it instead of migrating the JDK and the version together and building everything necessary for execution.

• I don't know if you consider this a problem, but since Spring Boot 4 was released with a JDK 17 baseline, this could be a motivator for some users to remain there, especially those who, for whatever reason, cannot migrate to JDK 25.

[graemerocher]

Micronaut 4.x will continue to support running on JDK 25 we also plan to maintain this line for a while.

The decision here is to choose a new minimum version for Micronaut 5.x

There are features like scoped values and Panama that mean it will be easier for us to maintain going straight to JDK 25

Scoped values we want to support for context propagation for example.

[lkishalmi]

JDK 25 base would probably the most compelling feature to use Micronaut 5.0.

[sdelamo]

Please note you an already use JDK 25 with Micronaut 4 today.

[lkishalmi]

Please note you an already use JDK 25 with Micronaut 4 today.

Well yes, I am already using JDK 25 with Micronaut 4.9 and it works great.

[Husan]

I think this is a really great idea.

[utkirbekQutfiddinov]

This is a great idea!

[sgammon]

Please do it!

[Nezisi]

JDK 25 as a baseline would mean that the full feature set of JDK 25 is available for the whole Micronaut 5 lifetime.

Micronaut 4: Jul 2023 release was 2 years ago

Azul and other distributions have longer supported life time, but e.g. RedHat OpenJDK builds:
https://endoflife.date/redhat-build-of-openjdk

For Azul:
https://endoflife.date/azul-zulu

So... regarding EOL, it will be almost 7 years from now, while JDK 21 and earlier usually have a smaller timeframe - JDK 17 already ending in a year.

TLDR: JDK 25 has longest time of support.

JDK 22 - 25 though had a lot of deprecation removals, virtual threads improvements, ... - imho thats the most important part.

Embracing a newer baseline than 17 - which is what most libraries did - would mean that Micronaut is definitely more future proof. Which I'd highly welcome, given that a framework like Micronaut has a wide range of libraries / plugins etc. - which are constantly evolving. E.g. uring / virtual threads / FFI / ...

TLDR: Newer baseline - more bulletproof, less deprecation support (as e.g. already removed in JDK), more features / better forward compatibility.

Sorry for the longer post, but I wanted to reflect a bit longer on the why. I think its a great decision compared to the rather conservative approach of just sticking to JDK 17 - which imho fuels the "lets stick to sth that is already deprecated in the planning phase" mentality (not meant offensive, but JDK 17 is already 2 LTS releases behind).

[sean-wils]

Yes please; the sooner the better.

[dstepanov]

The decision was made to use JDK 25 for Micronaut 5