Redis City

Type SET, GET, HSET, EXPIRE or BGSAVE into Redis City and the command travels through a 3D city built from one Redis instance. Each step is explained along the way: the RESP parser turning bytes into arguments, the arity, ACL and memory checks before execution, the main thread running the command, the key lookup in DB 0, and the allocator placing objects into slots on heap pages.

Guided experiments cover why RSS stays high after keys are deleted, how a BGSAVE child keeps its snapshot while the parent modifies copied pages, how AOF bytes become durable, what a simulated power loss throws away, and how allkeys-lru eviction behaves under a 144 KiB maxmemory limit. Everything runs in the browser against an educational model, not a live Redis server. The model is upfront about its simplifications, noting for instance that it samples five keys for eviction rather than using Redis's full ranked pool. A scene holds at most 96 keys.