[jeberle]

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...

[seanmcdirmid]

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.