2026-04-23: PGBouncer client connections per process nearing max_client_conn limit may cause refused connections

PGBouncer client connections per process nearing max_client_conn limit may cause refused connections (Severity 2)

Problem: Client connections per pgbouncer process for Primary_CI neared the configured max_client_conn limit, exceeding the service level objective and briefly impacting web service reliability.

Impact: For about 5 minutes around 03:20 UTC, web services experienced less than 2% error rates and a brief drop in Apdex by up to 3% for Workhorse and 0.4% overall. Some users may have seen errors or slow responses, but the issue resolved automatically.

Causes: A primary switchover in the Patroni CI cluster took longer than expected, leading to a spike in client connection usage and retries by applications.

Response strategy: The incident resolved automatically after the switchover completed. Teams confirmed the root cause and posted a public status update. No further action was required.

This ticket was created to track INC-9425, by incident.io 🔥