RFR: 8308645: Javadoc of FFM API needs to be refreshed [v4]

[Alan Bateman]

On Thu, 1 Jun 2023 21:12:08 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> I think SegmentAllocator should be agnostic re. thread safety. Allocation is a world of compromises, where if you give up (thread) safety you can gain more performance (and viceversa). So I think having a "one size fits all" thread-safety blanket might not work very well.

I'm just trying to think about the practical implications of this.  Arena is specified to be thread-safe so I can allocate from a non-confined Arena, and from concurrent threads, without needing to coordinate.  However, if you hand me a SegmentAllocator that is not an Arena then I don't know if I need to coordinate allocation with other parties. I'm not too concerned about the slicingAllocator and prefixAllocator factory methods as the result SegmentAllocators will likely be wrapped.

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PR Review Comment: https://git.openjdk.org/jdk/pull/14098#discussion_r1214092803