charlesdong1991 commented on code in PR #555: URL: https://github.com/apache/fluss-rust/pull/555#discussion_r3299499739
########## crates/fluss/src/metrics.rs: ########## @@ -49,6 +49,34 @@ pub const CLIENT_BYTES_RECEIVED_TOTAL: &str = "fluss.client.bytes_received.total pub const CLIENT_REQUEST_LATENCY_MS: &str = "fluss.client.request_latency_ms"; pub const CLIENT_REQUESTS_IN_FLIGHT: &str = "fluss.client.requests_in_flight"; +// --------------------------------------------------------------------------- +// Scanner poll-timing metrics +// +// Java reference: ScannerMetricGroup.java, LogScannerImpl.java +// +// These track consumer liveness and processing efficiency at the `poll()` +// boundary. Java records via `volatile long` fields read by gauge suppliers; +// Rust snapshots the values at poll start/end. +// +// Java's `lastPollSecondsAgo` gauge is intentionally NOT ported. Java +// implements it as a gauge supplier evaluated at scrape time, which the +// `metrics` crate facade has no equivalent for. A snapshot-at-poll-start +// port would just duplicate `time_between_poll_ms / 1000` and would not +// advance while a consumer is hung — defeating the metric's purpose +// (detecting a stuck consumer). Revisit if the `metrics` crate gains a +// supplier abstraction or we add a background liveness task. +// --------------------------------------------------------------------------- + +/// Gauge: milliseconds between the start of consecutive `poll()` calls. A +/// large value usually means the consumer's downstream processing is slow. +pub const SCANNER_TIME_BETWEEN_POLL_MS: &str = "fluss.client.scanner.time_between_poll_ms"; Review Comment: Good catch! just checked java side, indeed, it is per table path. > Can be a followup Ok, then i will create an issue and work on improvement -- 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]
