cheerpj-meta VS graalvm-reachability-metadata

- https://github.com/leaningtech/cheerpj-meta

>> That wouldn't be of use in any existing Java project though. The only reason you'd ever want to do that is because browsers offer nothing else, even though they could and at that point why not compile to JS, at least that way your GC isn't being interpreted too. If you're not constrained by the WHATWG's decisions though it doesn't offer anything.

It is very use case and "what is the future of your Java application" dependent. Some organizations are looking into migrating off of Java due to a variety of reasons. These kind of "Java conversion" tools help to keep legacy Java applications running until the legacy Java applications can be replaced.

I have no relation to this project, saw it on another subreddit a week or so ago I think, and haven't looked into it at all, but might be a fun useless thing to play with: https://github.com/leaningtech/cheerpj-meta

You can still write applets (although since Java might remove them completely, it's not a long term solution) and run them via CheepJ: https://github.com/leaningtech/cheerpj-meta

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

Yeah, I was able to get it working by adding some custom runtime hints. jOOQ support was recently added to the graalvm-reachability-metadata repo via this issue, so that may make things easier

During native image generation, native-image tool does a static analysis. There are classes which might not get accessed during this static analysis and they get left out in the final artifact. To overcome this some extra information can be provided during build time. Creating this extra metadata is cumbersome. There's an effort to consolidate these metadata information for various 3rd party libraries into a shared github repo https://github.com/oracle/graalvm-reachability-metadata .

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 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?)

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.

Most JVM libraries will require some amount of reflection for all frameworks as well, and for that we have made the bet to invest on a JVM wide effort -> https://github.com/oracle/graalvm-reachability-metadata.

The first issue should be solvable by refining Kotlin hints in https://github.com/oracle/graalvm-reachability-metadata that is used for non Spring hints with Boot 3.