kgyrtkirk commented on code in PR #20273: URL: https://github.com/apache/druid/pull/20273#discussion_r4090863380
########## docs/operations/metrics.md: ########## @@ -553,6 +553,26 @@ These metrics are emitted when `druid.auth.emitAuthMetrics` is set to `true`. |`segment/rowCount/avg`| The average number of rows per segment on a historical. `SegmentStatsMonitor` must be enabled.| `dataSource`, `tier`, `priority`|Varies. See [segment optimization](../operations/segment-optimization.md) for guidance on optimal segment sizes. | |`segment/rowCount/range/count`| The number of segments in a bucket. `SegmentStatsMonitor` must be enabled.| `dataSource`, `tier`, `priority`, `range`|Varies| +### HTTP client connection pools + +These metrics are only available if the `HttpClientPoolMonitor` module is included in `druid.monitoring.monitors`. +They cover the connection pools that Druid services use to talk to each other, one emission per remote end. The +`server` dimension is that remote end, and the `httpClient` dimension names the client that pools the connections to +it: `client` and `escalatedClient` are configured by `druid.broker.http`, `global` and `escalatedGlobal` by +`druid.global.http`. A remote end that a service has stopped talking to keeps being reported, with zeroes, until the +service is restarted. + +|Metric|Description|Dimensions|Normal value| +|------|-----------|----------|------------| +|`httpClient/pool/opened`|Number of connections opened.|`httpClient`, `server`|Varies. Steady churn on an idle cluster points at connections being discarded too eagerly.| +|`httpClient/pool/closed`|Number of connections closed, whether they were broken, unused for too long, or surplus.|`httpClient`, `server`|Varies| +|`httpClient/pool/errored`|Number of failures while opening, health checking, or closing a connection.|`httpClient`, `server`|0| +|`httpClient/pool/timedOut`|Number of connections discarded for being unused longer than `unusedConnectionTimeout`.|`httpClient`, `server`|Varies| +|`httpClient/pool/taken`|Number of connections handed to a caller, that is, the number of requests that got a connection.|`httpClient`, `server`|Varies| +|`httpClient/pool/returned`|Number of connections given back by a caller.|`httpClient`, `server`|Close to `httpClient/pool/taken`| +|`httpClient/pool/used`|Number of connections in the hands of callers at the time of the emission, that is, the requests in flight to that remote end. A level, not a per period count.|`httpClient`, `server`|<= `druid.<service>.http.numConnections`. Sitting at that ceiling means requests are waiting for a connection.| Review Comment: oh - sorry ; I was thinking that "I did not made any changes to the site" ...and it must be unrelated :facepalm: fixed it -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
