Live traffic analytics start showing stale congestion maps even though producers are publishing. Which operational metric should on-call engineers watch first on the bus?
Select an answer to reveal the explanation.
Short Explanation
If maps feel old while sensors still chatter, check consumer lag—how far behind the tip your readers sit. It is the speedometer for “are we keeping up?” on a city event bus. Stale dashboards often mean lag, not silent producers.
Full Explanation
Consumer lag measures the offset gap between the latest produced messages and what consumers have processed. Rising lag explains stale civic dashboards even when producers remain healthy. HDFS replication stats, endpoint device temperatures, or CapEx reports do not answer real-time bus freshness. Monitoring lag is a primary operational signal for Kafka-style ingestion health in municipal analytics.