[KAFKA-3959] KIP-115: __consumer_offsets wrong number of replicas at startup

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 0.9.0.1, 0.10.0.0, 0.10.0.1, 0.10.0.2, 0.10.1.0, 0.10.1.1, 0.10.1.2
• Fix Version/s: 0.11.0.0
• Component/s: consumer, offset manager, replication
• Labels: needs-kip reliability
• Environment: Brokers of 3 kafka nodes running Red Hat Enterprise Linux Server release 7.2 (Maipo)
• Assignee: Onur Karaman
• Reporter: Alban Hurtaud
• Reviewer: Ewen Cheslack-Postava
• Created: 13/Jul/16 09:12
• Updated: 12/May/17 04:03
• Resolved: 28/Feb/17 03:00

Description

When creating a stack of 3 kafka brokers, the consumer is starting faster than kafka nodes and when trying to read a topic, only one kafka node is available.
So the __consumer_offsets is created with a replication factor set to 1 (instead of configured 3) :

offsets.topic.replication.factor=3
default.replication.factor=3
min.insync.replicas=2

Then, other kafka nodes go up and we have exceptions because the replicas # for __consumer_offsets is 1 and min insync is 2. So exceptions are thrown.

What I missed is : Why the __consumer_offsets is created with replication to 1 (when 1 broker is running) whereas in server.properties it is set to 3 ?

To reproduce :

• Prepare 3 kafka nodes with the 3 lines above added to servers.properties.
• Run one kafka,
• Run one consumer (the __consumer_offsets is created with replicas =1)
• Run 2 more kafka nodes

Issue Links

• duplicates: KAFKA-4807 Kafka broker fail over bug in zookeeper
• is duplicated by: KAFKA-4446 If consumer offset topic created with less replicas than min.insync.replicas, consuming is not possible
• links to: GitHub Pull Request #2177
• links to: GitHub Pull Request #2484
• mentioned in: Page Loading...