Issue with stale consumer groups

[Suraj D <su...@gmail.com>]

Hi Dev,

At my company we run Kafka version 0.10.1.1 in production. I noticed a
strange behavior around stale consumers and wanted some help. So there are
some consumer group ids which are no longer being used, but kafka seems to
think that the group is rebalancing.

root@kafka32:/opt/kafka/bin# ./kafka-consumer-groups.sh --describe --group
consumer-abcd-defg-ads-9ffbcd955-8fdwn --bootstrap-server kafka1:9092
Consumer group `consumer-abcd-defg-ads-9ffbcd955-8fdwn` is rebalancing.

I see a message like the above. Since the kafka version I am on stores
consumer groups in _consumer_offsets (and not in ZK) I am not able to
delete these stale consumer groups.

1) Is this something I should be worried about? We might have ephemeral
consumer groups in our system and there could be stale consumer groups. I'm
worried that this might cause _consumer_offsets to blow up somehow? I saw
some bugs reported about this online
https://github.com/apache/kafka/pull/1622, so Im not sure if this actually
an issue or just a problem with ./kafka-consumer-groups.sh.

2) Is there a way I can cleanup these consumer groups?

Any help is appreciated!

Regards,
Suraj