Chris Thunes created KAFKA-6584:
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Summary: Session expiration concurrent with ZooKeeper leadership
failover may lead to broker registration failure
Key: KAFKA-6584
URL: https://issues.apache.org/jira/browse/KAFKA-6584
Project: Kafka
Issue Type: Bug
Affects Versions: 1.0.0
Reporter: Chris Thunes
It seems that an edge case exists which can lead to sessions "un-expiring"
during a ZooKeeper leadership failover. Additional details can be found in
ZOOKEEPER-2985.
This leads to a NODEXISTS error when attempting to re-create the ephemeral
brokers/ids/\{id} node in ZkUtils.registerBrokerInZk. We experienced this issue
on each node within a 3-node Kafka cluster running 1.0.0. All three nodes
continued running (producers and consumers appeared unaffected), but none of
the nodes were considered online and partition leadership could be not
re-assigned.
I took a quick look at trunk and I believe the issue is still present, but has
moved into KafkaZkClient.checkedEphemeralCreate which will [raise an
error|https://github.com/apache/kafka/blob/90e0bbe/core/src/main/scala/kafka/zk/KafkaZkClient.scala#L1512]
when it finds that the broker/ids/\{id} node exists, but belongs to the old
(believed expired) session.
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