Metrics

StateFun Actors jobs expose the standard Flink metrics unchanged. This page documents what this distribution adds on top. The reference deployments enable the Prometheus reporter on port 9249 (metrics.reporter.prom.factory.class, see flink-deployment.yaml in the E2E resources).

Invalid-record counters

Registered on the source operator's metric group of the routable Kafka ingress. They increment once per record skipped under invalidRecordHandling: skip (see Kafka I/O); under type: fail nothing increments because the first invalid record fails the job.

Both counters register inside the deserializer subgroup that KafkaSource hands to the deserialization schema, so their metric name lives under <operator>.deserializer.*:

Counter	Increments	Dimensions
numInvalidRecordsSkipped	once per skipped record, all topics of the ingress	none
numInvalidRecordsSkipped	once per skipped record of that topic and defect	topic, defect (key-value metric groups)

The per-topic breakdown uses addGroup("topic", …).addGroup("defect", …) - the two-argument, key-value form. topic and defect are the group keys, so they become dimensions (labels/tags in reporters that support them), not part of the metric name. <defect> is NULL_KEY or NULL_VALUE, matching the defect [...] field of the per-record skip log line.

The FLIP-33 standard numRecordsInErrors counter is deliberately not touched: it lives on the operator I/O metric group, which is not reachable from the deserializer context, and a same-named counter in a different scope would only mislead dashboards.

How each reporter renders it

The two representations are the same metric, rendered differently per reporter - this trips people up, so both are spelled out:

• JMX / Slf4j / other label-less reporters fold the key-value groups into the logical identifier: …deserializer.topic.<topic>.defect.<defect>.numInvalidRecordsSkipped. Here topic/defect and their values are part of the name.
• Prometheus turns key-value groups into labels. The metric name is flink_taskmanager_job_task_operator_deserializer_numInvalidRecordsSkipped and the breakdown arrives as labels: {topic="example.orders", defect="NULL_VALUE"}. The values are not in the name - query by label. Alert rules: Alerting.