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  • Geert Van Landeghem thinks this is interesting:

The consumer group name is unique and global across the Kafka cluster and any new consumers with an in-use consumer group name may cause ambiguous behavior in the system. When a new process is started with the existing consumer group name, Kafka triggers rebalance between the new and existing process threads for the consumer group. Post rebalance, some of the messages that are intended for a new process may go to an old process, causing unexpected results. To avoid this ambiguous behavior, any existing consumers should be shut down before starting new consumers for an existing consumer group name

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Cover of Apache Kafka

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