Caching¶

Read-through: miss loads from origin then populates cache — common for Astra's actor/profile keys. TTL bounds staleness; invalidation on write keeps correctness for mutable entities.

Cache stampede: many clients miss at once after expiry — mitigate with single-flight locking, staggered TTL jitter, or short-lived negative cache. At Astra scale, stampedes on hot agent keys are a real risk during incidents (Redis flap).

Memcached vs Redis: Memcached for large blob LLM responses; Redis for structured keys and streams — different eviction and data models.