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Kafka, mail # dev - [jira] [Created] (KAFKA-764) Race Condition in Broker Registration after ZooKeeper disconnect


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[jira] [Created] (KAFKA-764) Race Condition in Broker Registration after ZooKeeper disconnect
"Bob Cotton 2013-02-19, 21:07
Bob Cotton created KAFKA-764:
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             Summary: Race Condition in Broker Registration after ZooKeeper disconnect
                 Key: KAFKA-764
                 URL: https://issues.apache.org/jira/browse/KAFKA-764
             Project: Kafka
          Issue Type: Bug
    Affects Versions: 0.7.1
            Reporter: Bob Cotton
When running our ZooKeepers in VMware, occasionally all the keepers simultaneously pause long enough for the Kafka clients to time out and then the keepers simultaneously un-pause.

When this happens, the zk clients disconnect from ZooKeeper. When ZooKeeper comes back ZkUtils.createEphemeralPathExpectConflict discovers the node id of itself and does not re-register the broker id node and the function call succeeds. Then ZooKeeper figures out the broker disconnected from the keeper and deletes the ephemeral node *after* allowing the consumer to read the data in the /brokers/ids/x node.  The broker then goes on to register all the topics, etc.  When consumers connect, they see topic nodes associated with the broker but thy can't find the broker node to get connection information for the broker, sending them into a rebalance loop until they reach rebalance.retries.max and fail.

This might also be a ZooKeeper issue, but the desired behavior for a disconnect case might be, if the broker node is found to explicitly delete and recreate it.

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