IBM Event Streams Idempotent Producer with IBM Cloud Functions: Handling Retries Without Duplicate Writes

Goal: Use IBM Event Streams idempotent producer to guarantee that retries from IBM Cloud Functions do not result in duplicate writes to downstream systems while maintaining exactly‑once semantics per partition.

Constraints: Idempotence only suppresses duplicates within a single producer session; a new Producer ID is generated if the producer is recreated, which can happen when Cloud Functions scale to new instances. Additionally, enabling idempotence forces max.in.flight.requests.per.connection to 5, potentially affecting throughput for high‑volume functions.

Questions: What pattern ensures the same producer instance (and thus the same PID) is reused across multiple Cloud Function invocations? How does the reduced max.in.flight setting impact latency and throughput for latency‑sensitive workloads? Are there any interactions between Cloud Functions built-in retry mechanism and the idempotent producer duplicate suppression that require additional configuration?