We recently updated our Kafka brokers and clients to 1.1.0. Since the upgrade we periodically see INFO log entries such as
INFO Jun 08 08:30:20.335 61161458 [KafkaRecordConsumer-0] org.apache.kafka.clients.FetchSessionHandler [Consumer clientId=consumer-1, groupId=group_60_10] Node 3 was unable to process the fetch request with (sessionId=819759315, epoch=145991): INVALID_FETCH_SESSION_EPOCH. I see that this message comes from the changes introduced in KIP-227: Introduce Incremental FetchRequests To Increase Partition Stability <https://cwiki.apache.org/confluence/display/KAFKA/KIP-227%3A+Introduce+Incremental+FetchRequests+to+Increase+Partition+Scalability>. However, I cannot find any detailed information about why this message would appear or what parameters might have to be tuned after its introduction. So far it doesn't seem to have an impact on consumer behaviour with respect to receiving records but I would like to understand 1. Why is the message being logged? 2. Do I need to do anything? 3. Can anything be done to stop it being logged? Thanks, Mark
