Comment by bbminner
6 months ago
Ok, now give me an example of a resource manager (eg in a game) that has methods for loading resources into memory and also for releasing such resources - all of a sudden if a system needs to give away pointer access to its buffers, things become more complicated and arena allocators are not enough.
For that scenario you can use a pool allocator backed by a fixed size allocation from an arena. That gives you the flexibility to allocate and free resources on the fly, but with a fixed upper limit to the lifetime (e.g. the lifetime of the level or chunk). Once you're ready to unload a level or a chunk, you can rewind the arena, which is a very cheap operation (as opposed to calling free in a loop, which can be expensive if the free implementation tries to defragment the freelist)
I am not sure how this would be a problem. Certainly the resource manager should manage the memory itself in some manner.
It has very little to do with trying to manage temporary memory lifetimes.