[Eval][v3][en] Third-party payment gateway timeouts cascade into checkout outage

Summary

Severity reasoning: User-facing outage: error rate > 1% for >5 min (78% failure rate for 5+ minutes), revenue path broken (failed checkouts ~3000, lost GMV $180k). Matches SEV1 criteria.

deepseek-chat·prompt v3·output: en·12615ms·2002↑ / 1892↓ tok·$0.00262

Root cause hypotheses

• highStripe Connect API latency spike causing thread pool exhaustion

  Evidence: APM shows Stripe /v1/payment_intents p99 jumped from 800ms to 27s; thread pool utilization 100%; success rate 22%.

• highNo circuit breaker on Stripe client allows unbounded retries

  Evidence: Config review: no circuit breaker or bulkhead; Stripe calls share main worker thread pool.

• mediumInbound request queue overflow causing additional timeouts

  Evidence: Queue depth 4200 (limit 5000), nearing capacity; could amplify failures.

• highStripe API degradation due to regional issue in us-east-1

  Evidence: Stripe status page: 'Investigating elevated latency for Connect endpoints in us-east-1' posted 18:35 UTC.

• lowApplication-level bug causing excessive Stripe calls per checkout

  Evidence: No evidence in context; normal call pattern assumed.

Investigation checklist

1. Confirm Stripe latency via APM and logs

   kubectl logs -n prod -l app=checkout-svc --since=20m | grep -iE 'stripe|payment_intent|timeout' | tail -50

   Copy

   Expected: Logs showing Stripe calls taking >20s or timing out

2. Check thread pool and queue metrics

   curl -s http://checkout-svc:8080/metrics | grep -E 'thread_pool|queue_depth'

   Copy

   Expected: thread_pool_utilization 1.0, queue_depth ~4200

3. Verify Stripe status page

   curl -s https://status.stripe.com/api/v1/incidents | jq '.incidents[] | select(.status != "resolved")'

   Copy

   Expected: Active incident for Connect endpoints in us-east-1

4. Check downstream dependencies (auth-svc, fraud-svc) latency

   kubectl logs -n prod -l app=checkout-svc --since=20m | grep -iE 'auth|fraud' | tail -20

   Copy

   Expected: Normal latency (<1s)

5. Review circuit breaker configuration

   kubectl exec -n prod deploy/checkout-svc -- cat /app/config.yaml | grep -A5 'stripe'

   Copy

   Expected: No circuit breaker or bulkhead configured

Mitigation plan

• Enable circuit breaker for Stripe calls with fallback to fail-fast (e.g., return 503 immediately after 5s timeout)

  Risk: May cause partial checkout failures but prevents thread pool exhaustion; safe to rollback

  Rollback: Disable circuit breaker via feature flag or config reload

• Increase thread pool size temporarily (e.g., from 200 to 400) to absorb latency spike

  Risk: May increase memory pressure; could mask underlying issue

  Rollback: Revert thread pool size to 200

• Implement bulkhead for Stripe calls (dedicated thread pool of 50 threads)

  Risk: May limit throughput to Stripe; safe to rollback

  Rollback: Remove bulkhead config

• If Stripe degradation persists >15 min, disable Stripe payment path and fall back to alternative provider or manual processing

  Risk: Lost revenue from Stripe payments; requires manual intervention

  Rollback: Re-enable Stripe path after Stripe resolves

Customer impact

Approximately 78% of checkout attempts are failing with a 504 error. Users see a timeout or error page after waiting up to 30 seconds. Estimated 3,000 failed checkouts in the last 5 minutes, resulting in approximately $180k lost revenue. No data loss; payments are not processed.

Postmortem draft

Follow-ups

• P0Add circuit breaker to Stripe client with fallback— checkout-svc team
• P0Implement bulkhead for Stripe calls (dedicated thread pool)— checkout-svc team
• P1Set up synthetic monitoring for Stripe latency and alerting— platform team
• P1Document runbook for Stripe degradation with step-by-step mitigation— on-call SRE
• P2Evaluate alternative payment provider for failover— payments-platform
• P2Review thread pool sizing and queue limits for checkout-svc— checkout-svc team