KIP-225 — Use tags for consumer “records.lag” metrics

Accepted Kafka 1.1 ConsumerMetrics

Renames the consumer records-lag metric from a per-topic-partition name prefix (topic-partition.records-lag) to a constant name records-lag with topic and partition as metric tags under consumer-fetch-manager-metrics. The name-encoded approach prevented metric aggregation tools and custom reporters from grouping lag across topics/partitions, causing a cardinality explosion.

Details