spring-boot - Spring kafka，ConsumerSeekAware接口(interface)，再平衡时是否调用onPartitionsAssigned方法

Question

重新平衡时是否调用 ConsumerSeekAware 接口(interface)、onPartitionsAssigned 方法。因为我想在初始化和重新平衡时寻找偏移量中的特定偏移量。我可以将 consumerSeekAware 用于这两个目的，还是应该将 ConsumerRebalanceListener 用于重新平衡目的。请给出简单的答案，因为我对 spring kafka 还没有深入的了解。如果可以，请提供示例代码。谢谢

Answer 1

ConsumerSeekAware有这个方法:

/**
 * When using group management, called when partition assignments change.
 * @param assignments the new assignments and their current offsets.
 * @param callback the callback to perform an initial seek after assignment.
 */
void onPartitionsAssigned(Map<TopicPartition, Long> assignments, ConsumerSeekCallback callback);

它是从 KafkaMessageListenerContainer.seekPartitions(Collection<TopicPartition> partitions, boolean idle) 调用的。 ，而这又来自 ConsumerRebalanceListener.onPartitionsAssigned()内部实现。最后一个有这个JavaDocs:

 * A callback method the user can implement to provide handling of customized offsets on completion of a successful
 * partition re-assignment. This method will be called after an offset re-assignment completes and before the
 * consumer starts fetching data.

所以，是的，ConsumerSeekAware.onPartitionsAssigned()在重新平衡期间总是调用。顺便说一句，Apache Kafka 没有像 initializing 这样的状态。 .总是 rebalancing - 代理处于等待状态，并在有新消费者加入时开始重新平衡。