Arenas are great for latency sensitive programming. But some of the advice in this piece is a bit limited in that it assumes the presence of swap (often disable

Arenas are great for latency sensitive programming. But some of the advice in this piece is a bit limited in that it assumes the presence of swap (often disabled on server hardware) and programs whose important "hot" datasets are likely to fit in memory (i.e. the memory use is nice and predictable--an enviable but not always achievable property). When working with bursty memory demands and code/data you don't always fully control (think a big thick runtime with its own allocation decisions, some of them decidedly "1975") on a system whose swapping behavior you can't predict, hand managing on-disk versus in-memory data residency in userland (via manual memory mapping or something like sqlite/lmdb to take care of it for you) becomes necessary.