Add blog post about Java 24 upgrade

Author: mosabua

_posts/2025-03-03-java-24.md

@@ -0,0 +1,93 @@
+---
+layout: post
+title: Twenty four 
+author: Manfred Moser, Mateusz Gajewski
+excerpt_separator: <!--more-->
+image: /assets/blog/coffee-24.png
+---
+
+Six month ago [we adopted Java 23 as requirement]({% post_url 2024-09-17-java-23
+%}), following our standard procedure to upgrade with each Java version as soon
+as it becomes available. This allows us to take advantage of all the great
+improvement each release brings. The upgrade to 23 was pretty easy since the
+changes from 22 to 23 were not that big. The story turns out to be a bit
+different now with our upgrade to Java 24.
+
+<!--more-->
+
+## Java 24 features
+
+We have been [planning and working towards the
+upgrade](https://github.com/trinodb/trino/issues/23498) consistently since the
+23 bump in September. Java 24 is set to be released in March 2025 and the list
+of changes is quite significant:
+
+* JEP 450 Compact Object Headers (Experimental)
+* JEP 472 Prepare to Restrict the Use of JNI
+* JEP 475 Late Barrier Expansion for G1
+* JEP 478 Key Derivation Function API (Preview)
+* JEP 483 Ahead-of-Time Class Loading & Linking
+* JEP 484 Class-File API
+* JEP 485 Stream Gatherers
+* JEP 486 Permanently Disable the Security Manager
+* JEP 487 Scoped Values (Fourth Preview)
+* JEP 488 Primitive Types in Patterns, instanceof, and switch (Second Preview)
+* JEP 489 Vector API (Ninth Incubator)
+* JEP 490 ZGC: Remove the Non-Generational Mode
+* JEP 491 Synchronize Virtual Threads without Pinning
+* JEP 492 Flexible Constructor Bodies (Third Preview)
+* JEP 494 Module Import Declarations (Second Preview)
+* JEP 495 Simple Source Files and Instance Main Methods (Fourth Preview)
+* JEP 496 Quantum-Resistant Module-Lattice-Based Key Encapsulation Mechanism
+* JEP 497 Quantum-Resistant Module-Lattice-Based Digital Signature Algorithm
+* JEP 498 Warn upon Use of Memory-Access Methods in sun.misc.Unsafe
+* JEP 499 Structured Concurrency (Fourth Preview)
+
+The list of new features is also quite large. You can find more details
+in the [release notes](https://jdk.java.net/24/release-notes) and each
+individual JEP.
+
+## Trino perspective
+
+From a Trino perspective we want to specifically take advantage of performance
+improvements to MemorySegment (mismatch, copy, fill), "JEP 491 Synchronize
+Virtual Threads without Pinning" and "JEP 475 Late Barrier Expansion for G1". On
+the other hand [JEP 486 Permanently Disable the Security
+Manager](https://openjdk.org/jeps/486) turned out to be the most impactful.
+
+Since Trino and its connectors have a large footprint of dependencies there was
+a high chance that some projects as not keeping up with the security manager
+removal, although it was first deprecated with Java 17 in 2021. 
+
+At this stage the Kafka, Kudu, and Phoenix connectors are affected. The Kafka
+project is planning to make a new compatible release available in time and we
+will adopt that version.
+
+The Kudu and Phoenix connectors however will be removed, since it is not
+possible to use them with Java 24 as requirement. Both connectors are not
+heavily used in our community as we learned from our communication with numerous
+users, integrators, and the results from our [user survey]({% post_url
+2025-01-07-2024-and-beyond %}). We are tracking progress for each removal in the
+issues [#24419 Phoenix connector](https://github.com/trinodb/trino/issues/24419)
+and [#24417 Kudu connector](https://github.com/trinodb/trino/issues/24417). If
+either of these communities ends up supporting Java 24, or a newer version as
+required by Trino, in the future, we can potentially add the connectors back in
+if community members contribute updated versions.
+
+## Release plans
+
+In terms of shipping the changes we follow our established pattern:
+
+* Clean up codebase and get it ready, specifically this include the removal of
+  the Kudu and Phoenix connectors.
+* Cut a release that is completely ready to be used with Java 24, but does not
+  yet make it a hard requirement
+* Allow for community testing and feedback using Java 24.
+* Introduce Java 24 as hard requirement in another release.
+* Adopt Java 24 features and bring the benefits to our users with following
+  releases.
+
+As you see, there is a bunch of work waiting, we we better back to it. As usual,
+if you have questions or comments, chime in on the relevant issue or chat with
+us on [Trino Slack]({{site.baseurl}}/slack.html) in the [core-dev
+channel](https://{{site.slack_fqdn}}/messages/C07ABNN828M).