🔒 Paid
Hot-Key Cache Overload
A single extremely popular cache key is receiving a sudden surge of read traffic. The distributed cache hashes that key to one specific shard, and that shard's request rate, utilization, and latency are climbing sharply while the rest of the cluster stays flat. The origin service behind the cache has limited headroom and must not be overwhelmed by repeated fetches for the same key. Diagnose why this one shard is saturated while its neighbors sit idle, and bring it back to a durable, sustainable state.
- Difficulty
- Senior
- Expected Time
- ~15 min
- Category
- Caching
Skills
- Diagnosing single-key cache hotspots versus cluster-wide capacity problems
- Distinguishing a targeted fix from a cluster-wide capacity increase
- Evaluating request coalescing and local caching as origin-protection strategies
- Recognizing when a mitigation clears symptoms by sacrificing a different guarantee
System Architecture
- Clients
- API
- Cache Shard (Hot Key)
- Cache Cluster (Other Shards)
- Origin Service
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