At-Most-Once: Fire and Forget

At-most-once is the least discussed semantic but it appears in interviews as a trap. The interviewer describes a use case (monitoring metrics, debug logs) and waits to see if you over-engineer it with exactly-once. The strong candidate says 'this is at-most-once territory; losing a few metrics samples is acceptable and the simplicity is worth it.' How It Works Commit the offset BEFORE processing. If the consumer crashes after committing but before finishing, the message is lost. No retry, no reprocess. The message is gone. When At-Most-Once Is Correct The Interview Trap The interviewer says: 'We need to send CPU metrics from 10,000 servers to a monitoring dashboard every 5 seconds.' The trap is over-engineering this with exactly-once semantics. The strong answer: 'At-most-once. If we lose