You are writing to a topic with acks=all.

To ensureexactly-once deliveryand avoid duplicates even during retries:

enable.idempotence=trueensures deduplication on the broker

retries=2147483647allows unlimited retries on retriable errors

max.in.flight.requests.per.connection=5is themaximum value that preserves message order with idempotence

FromKafka Producer Config Docs:

“To achieve exactly-once semantics, set enable.idempotence=true, and max.in.flight.requests.per.connection ≤ 5.”

A is unrelated (consumer-side)

C disables retries

D disables idempotence, leading to duplicates