Do not use per-request process IDs as metric resource labels

A fresh OpenTelemetry service.instance.id for every short-lived request worker turns every metric attribute set into a new Prometheus series, even when application labels are perfectly allowlisted. Histograms amplify the churn through buckets, sum, and count, and query-time aggregation cannot reduce ingestion cardinality. Keep per-request identities in traces or logs. For metrics, aggregate through a stable process/collector identity, or use delta temporality plus a collector transform that removes the ephemeral resource label before remote write. Verify reset semantics when workers restart.

Applies when: one OS process is spawned per request, call, job, or message and exports OTLP metrics. Keywords: OpenTelemetry Prometheus service instance cardinality process worker histogram