Native Memory in Java: Arenas, Malloc, and Pools

A practical guide to managing native memory in Java using the Foreign Function & Memory (FFM) API. Covers the four built-in Arena types (global, auto, confined, shared) with their lifetime and thread-safety trade-offs, how to implement a custom Arena wrapper, using C-level malloc/free via downcall handles for maximum control, building reusable memory pools with ConcurrentLinkedQueue, and slicing large memory blocks with asSlice and SegmentAllocator. Concludes with a comparison table of all strategies by allocation speed, safety, and best use cases.