[gpderetta]

I have succesfully used the mmapped state trick in the past, although for crash resilience (with carefully maintaining invariants at instruction boundaries) not just for persistence.

It worked well with fixed size objects, although if I would do it again today I would still allow for a separate pool for variable size strings as updating the max string size was the most common change that both breaks the file compatibility and bloats the size.

The separate pool would make it more awkward to dereference the string as you can't neither use a dumb pointer nor the self offset trick but you have to pass the poll base offset explicitly (or implicitly with a global), but I think it would be worth it.

edit: thinking about it, interleaving fixed size string pools with the other objects might also work, in practice you get a persistent heap.