Java's Plans for 2024 - Inside Java Newscast #61

Summary

The transcript covers upcoming Java language and JVM features that are expected to be worked on in 2024. It focuses on the major OpenJDK projects like Project Babylon, Project Loom, Project Leyden, Project Amber, Project Panama, Project Valhalla, and Project Lilliput. The key points are: - Project Babylon will expand Java's reflection API to allow code analysis and transformation. This enables use cases like auto-differentiation, GPU programming, and more. Babylon is still in early stages so major updates are not expected in 2024. - Project Loom brought virtual threads, structured concurrency and scoped values APIs which will likely finalize in 2024. Work remains to make synchronization non-pinning and file I/O non-capturing. Unclear if that will happen in 2024. - Project Leyden has shown 50-80% performance improvements for Spring Boot without constraints. The focus in 2024 is bringing these optimizations out of prototype stage into production use. Unlikely to see tangible changes in 2024. - Project Amber will finalize string templates, simplified main, and statements before this()/super() in 2024. Exciting new feature on the horizon is 'with' expressions for boilerplate-free record copies. Also considering expanding switch for exceptions and deconstruction assignments. - Project Valhalla will focus on JEP 401 value types and objects in 2024. Other topics like nullness markers and generic specialization unlikely to see public progress until JEP 401 stabilizes. - Project Panama will improve the Foreign Function Interface API and jextract native binding tooling. Vector API remains in incubation. - Project Lilliput aims to reduce object header sizes but alternative locking needs more work before that can happen. Unlikely to see header size reductions in 2024. The overarching message is that while many OpenJDK projects made great progress in 2023, 2024 will be focused on incremental improvements, stabilization and hardening features for production use rather than big splashy changes.

Takeaways

• Project Babylon aims to expand Java's reflection API to allow code analysis and transformation.
• Project Loom is nearing completion, with virtual threads and structured concurrency APIs finalized.
• Project Leyden is working to bring considerable performance improvements to all Java code.
• Project Amber continues driving Java's language evolution with features like string templates and `with` expressions.
• Progress is being made on value types and generics specialization in Project Valhalla.
• Project Panama focuses on improving APIs for calling native code from Java.
• Project Lilliput aims to reduce object header sizes to improve memory efficiency.
• A prototype for code reflection in Project Babylon was recently published.
• Features like pattern matching and records set the stage for upcoming work on `with` expressions.
• Improvements like fast-locking are needed before Lilliput can reduce header sizes.

Q & A

What is the goal of Project Babylon?

Project Babylon aims to expand Java's reflection API to allow code analysis and transformation. This will enable use cases like differentiating mathematical functions expressed in Java code.

What is the current status of Project Loom?

Project Loom is nearing completion, with key features like virtual threads and structured concurrency APIs already finalized in JDK versions. The remaining work is focused on smaller improvements and additions.

How does Project Leyden improve performance?

Project Leyden introduces an optional 'condenser' phase that shifts computation earlier and applies optimizations, speeding up the final program without requiring code changes.

What features is Project Amber working on?

Project Amber is driving Java's language evolution. Some current features under development are string templates, simplified `main`, statements before `this()`/`super()`, and `with` expressions.

What is the focus of Project Valhalla?

Project Valhalla is focused on value types and generics specialization. Specifically, work is progressing on JEP 401 for value classes and objects.

What does Project Panama aim to improve?

Project Panama focuses on improving APIs for calling native code from Java. Work in 2024 will focus on improving the jextract tool and tooling.

What is Project Lilliput's goal?

Project Lilliput aims to reduce object header sizes to improve memory efficiency. This requires work like the fast-locking scheme before header sizes can be reduced.

What recent progress was made on Project Babylon?

A prototype for code reflection was recently published to the Project Babylon repository, enabling initial use cases.

How do recent features relate to `with` expressions?

Features like pattern matching and records lay the groundwork for `with` expressions by enabling deconstruction of immutable objects.

What does Lilliput need to do before reducing header sizes?

Improvements like the alternative fast-locking scheme are needed in Lilliput before header sizes can be reduced.