Uhm, I'd suppose the service runs on one or more dedicated nodes - so there should be no competition for RAM (or if a node runs multiple services, the I'd expec

Uhm, I'd suppose the service runs on one or more dedicated nodes - so there should be no competition for RAM (or if a node runs multiple services, the I'd expect a fixed memory amount to be available). In such an environment, each fixed size LRU cache could just allocate a huge chunk of RAM for data + indices (index size is bound by data size). That's nothing to do with the ownership model, it's just manually managed memory. Yes, reality is more complex since they probably have multi socket servers/NUMA, which might add memory access latencies and atomic updates to the LRU might require a locking scheme, which also isn't trivial (and where async Rust might be useful).