Serial Execution Masking Redis Cache Effectiveness
warningEvent loop blocking creates false appearance of cache ineffectiveness - Redis cache hits are fast individually, but serial request processing prevents concurrent cache lookups from improving overall throughput during traffic bursts.
Monitor for high redis.keyspace.hits ratio (indicating cache is working) but throughput plateaus earlier than expected during load tests. Look for redis.commands.usec_per_call staying low while overall request latency (client_operation_time) remains high, especially at higher concurrency levels.
Profile request concurrency patterns to identify whether cache lookup parallelism is being achieved. If cache operations are fast but throughput is still limited, investigate event loop blocking in the application layer. Consider batching cache operations where possible and ensuring they use async Redis clients.