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In this scenario, if auto commit is enabled, we would commit offsets from buffer2 directly into the original commit log. Meanwhile, the offsets found in buffer1 will be checkpointed in another Kafka topic. Once When calling KafkaConsumer#fetchCommittedOffsets or KafkaConsumer#committed, if consumer2 has not terminated, we would merge both commit logs into a larger one, then only offsets checkpointed by consumer2 will be sent. Otherwise, the offsets checkpointed by consumer2 will be returned instead.

Effects on KafkaConsumer#poll()

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