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Not sure what you mean by "primitive support". Java 22 added FFM (Foreign Function & Memory). It works w/ both on-heap & off-heap memory. It has an Arena interface.

https://openjdk.org/jeps/454

https://docs.oracle.com/en/java/javase/25/docs/api/java.base...

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So, one year ago? After more than 25 years without it?

And a lot of people writing Java can't update to that.

Yeah, FFM adds many quality-of-life features - scoped lifetimes being a standout.

If you just want an arena interface, ByteBuffer has been there since Java 1.4 (2002). It also does off-heap w/ ByteBuffer.allocateDirect().

https://docs.oracle.com/en/java/javase/25/docs/api/java.base...

That brings back some memories...when Frank Yellin and Sheng Liang (from Javasoft) visited our team at UW I think in 1996 or 1997, we mentioned that our bytecode verifier/failure injector was really fast because we were using arena allocation, which was only possible (at the time) because we did the project in C. If you are using non-pointer offsets, you totally can do arena allocation with a byte buffer. I still don't get how you can do it safely with high level objects even with the mechanism described above, but there are definitely lots of unsafe ways to do it.

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