What does HackerNews think of graalvm-reachability-metadata?

GraalVM for JDK 21 | Sep 2023

gcj had a lot of problems beyond needing configuration of reflection metadata. It used a full reimplementation of the standard library, and it was never adopted by the wider Java community being largely just Red Hat's strategy for creating a fully open source Java implementation rather than something offering specific benefits to Java developers. In particular people thought it'd lead to faster code, but GCC was never designed for Java and the results were actually a fair bit slower iirc.

Native image is quite different. With this new release the compiled images can not only be faster than JIT compiled Java (wow) but also use way less memory and start instantly. At a stroke this is resolving one of the biggest complaints people have always had against JVM languages.

And as a consequence you're seeing adoption by the wider community. All the modern Java web frameworks support it now, and there's a metadata repository where it's collected for projects that haven't accepted it upstream yet [1].

[1] https://github.com/oracle/graalvm-reachability-metadata

Oracle Contributing GraalVM Community Edition Java Code to OpenJDK | Oct 2022

GraalVM is truly great stuff.

GraalVM native compilation helps Java in the data center to avoid being a cost sink and to reduce start-up latency. Oracle needs Java to sell enterprise software.

Oracle contributing to OpenJDK may be required for Amazon cooperation (since Amazon is pushing its own JDK build) and probably helps the library ecosystem work towards native compatibility.

Native support for reflection (used in many libraries) requires "reachability metadata", maps of reflective API usage, at build time. Anyone can do it, but enterprise requires authoritative sources. Until authoritative reachability metadata covers the transitive graph of library+version dependencies in enterprise software, GraalVM native AOT builds are a PITA.

- https://github.com/oracle/graalvm-reachability-metadata

- latest release: https://medium.com/graalvm/graalvm-22-3-is-here-jdk-19-build...

- graalvm "community" roadmap: https://github.com/orgs/oracle/projects/6

(As a side note: Mark Reinhold has run the JDK team since 1997: is there any comparable example of such stellar leadership for broadly-adopted software across multiple technical and organizational eras?)

GraalVM 22.3: JDK 19 builds, jlink support, new monitoring features, and more | Oct 2022

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Also, reflection is supported in AOT mode. The analysis, however, does require reachability metadata in some cases. In the best case, libraries provide and maintain appropriate configuration for this. Reachability metadata can also be shared via https://github.com/oracle/graalvm-reachability-metadata.