module PrometheusExporter

Custom ActiveRecord type collector that sums connection pool metrics across all worker processes and excludes pid from Prometheus labels to avoid high-cardinality metric series.

Each worker still sends pid for dedup (so the MetricsContainer stores one entry per worker). The metrics method then groups by hostname + pool_name, sums the gauge values, and emits a single metric per group.

Registered via Runner’s type_collectors option in bin/prometheus_exporter, which overwrites the default ActiveRecordCollector (same type: “active_record”).