Hello Apache Kafka community, In the new consumer I encountered unexpected behavior. After constructing KafakConsumer instance with configured consumer rebalance callback handler, and subscribing to a topic with "consumer.subscribe(topic)", retrieving subscriptions would return empty set and callback handler would not get called (no partitions ever assigned or revoked), no matter how long instance was up.
Then I found by inspecting KafkaConsumer code that partition assignment will only be triggered on first poll, pollOnce has: // ensure we have partitions assigned if we expect to if (subscriptions.partitionsAutoAssigned()) coordinator.ensurePartitionAssignment(); Would it make sense to include this fragment in KafkaConsumer.subscriptions accessor as well? Kind regards, Stevo Slavic.