[Question] Receiving multiple times the same Consumer Groups

[pawelcit]

Description

I've tried this example code to list consumer groups of my 3 clusters and noticed that on one of them I get 1x (majority of cases) 2x and 3x the same Consumer Groups names (5k consumer groups in total). I cannot see anything suspicious in the logs. The cluster has been fully rebooted before the test. The result is repeatable, it gives the same result (the same consumer groups) every time.

Example result:

GroupId: consumer_group_1
State: Stable
IsSimpleConsumerGroup: false

GroupId: consumer_group_1
State: Empty
IsSimpleConsumerGroup: false

GroupId: consumer_group_1
State: Empty
IsSimpleConsumerGroup: false

Kafka's tool lists cosnumer groups without duplicates: ./kafka-consumer-groups.sh --list --bootstrap-server 127.0.0.1:9094

Does anyone know what could be causing that? Cluster misconfiguration? What else could I check?

Checklist

Please provide the following information:

• [ ] confluent-kafka-go and librdkafka version (LibraryVersion()): v2.2.0
• [ ] Apache Kafka broker version: 2.6.1
• [ ] Number of brokers: 13
• [ ] Number of Consumer Groups: over 5k

[milindl]

Hi @pawelcit , thanks for bringing this up. I can't seem to reproduce it, but that could just be due to the difference in number of brokers and consumer groups. I was trying with the same broker version, but with 3 brokers and a ~250 consumer groups.

Is it possible for you to repeat this with "debug" set to "all" in the configuration of the admin client, and share the logs?

[pawelcit]

Hello @milindl, here they are: https://gist.github.com/pawelcit/92e9a1ee29cb12f164687690bc7b4204