Hacker News Reader

> Logs and metrics are both derived from events. A log takes the whole event and records it somewhere. A metric takes some numeric value from the event, aggregates it over time, and records it periodically. You can reconstruct a metric from logs for the underlying events.

No, metric is just value. Some are derived from events (like histogram/rate of given event duration) but others are wholly independent (like returning app's CPU/memory usage)

View on HN

The app's memory usage is an aggregation of the alloc/free events. I think the original point was that all of the metrics, traces and logs are conceptually the same but for efficiency, we store less data in each place, not the full history. Personally, for the systems I work on, having an easy way to turn logs into metrics and vice versa, without deciding up front, would be a slight benefit.

A clock ticking every second is generating an event every second.

If you sample the CPU usage at 1Hz, the metric is attached to the tick event.

Reply on news.ycombinator.com