A Kafka cluster experienced severe performance degradation when eight single-member consumer groups, each fetching 4,742 partitions, caused lock contention in the broker's DelayedFetch mechanism. The issue emerged after upgrading to Kafka 2.7+, which changed lock acquisition to blocking mode, starving request handlers and blocking network threads while broker-measured latency metrics remained artificially low because time spent in unread sockets goes unmeasured.
Readpanda is a terminal UI for Kafka and Redpanda that displays topics, consumer groups, lag, and live message tails with support for Avro, JSON-SR, and Protobuf decoding. It provides a lightweight alternative to the Redpanda Cloud console and requires Docker and Go 1.26+ to run.