I remember in the early days of web services, using the apache portable runtime, specifically memory pools.

If you got a web request, you could allocate a memory pool for it, then you would do all your memory allocations from that pool. And when your web request ended - either cleanly or with a hundred different kinds of errors, you could just free the entire pool.

it was nice and made an impression on me.

I think the lowly malloc probably has lots of interesting ways of growing and changing.