new Map() is a memory leak

Memoize getUser with a Map and nothing ever leaves: the process runs out of memory, restarts empty, and the graph climbs again. A sawtooth on your memory dashboard is a cache with no limit. Fix: an LRU with a size limit and a TTL. Memory goes flat.

Comment below: What's the biggest Map in your codebase?

Two Hard Things: a series on the caching bugs you already ship, and how to fix them. "There are only two hard things in computer science: cache invalidation and naming things." (Phil Karlton) All code is real TypeScript on Node, typechecked before it went on screen, and every claim was reproduced against real Redis and Postgres.