CachingdebuggingAdvanced

One Redis node is at 100% while the others idle

Symptoms

  • A sharded Redis cluster has one node pinned at 100% CPU; the rest are near idle.
  • Latency on that node’s keys is high; adding nodes does not help.
-- key access distribution (top keys by ops/sec):
config:global      420,000 ops/s   ← one key
user:*  (aggregate) 180,000 ops/s
everything else      ~60,000 ops/s

Investigate

Inspect areas in any order (0/4 inspected). When you think you know the root cause, commit to it.

Per-key operation counts
Sharding
Node hardware
Network