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https://issues.apache.org/jira/browse/FLINK-6006?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15939885#comment-15939885
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Tzu-Li (Gordon) Tai commented on FLINK-6006:
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[~gyfora] no problem. Here's how I'll proceed with this:
I'll try to add some logs into the Kafka Consumer in 1.2.1 so that if this
issue pops up again, there'll at least be good logs to serve as the ground for
debugging.
I'll perhaps do another thorough check before creating the candidate for 1.2.1
to see where this could have gone wrong, but as I have mentioned from my
earlier check, right now I can't really find anything. If there is still a bug
and we only manage to solve it after 1.2.1, we could always push out 1.2.2 asap.
Really sorry you had to cope with this.
> Kafka Consumer can lose state if queried partition list is incomplete on
> restore
> --------------------------------------------------------------------------------
>
> Key: FLINK-6006
> URL: https://issues.apache.org/jira/browse/FLINK-6006
> Project: Flink
> Issue Type: Bug
> Components: Kafka Connector, Streaming Connectors
> Reporter: Tzu-Li (Gordon) Tai
> Assignee: Tzu-Li (Gordon) Tai
> Priority: Blocker
> Fix For: 1.1.5, 1.2.1
>
>
> In 1.1.x and 1.2.x, the FlinkKafkaConsumer performs partition list querying
> on restore. Then, only restored state of partitions that exists in the
> queried list is used to initialize the fetcher's state holders.
> If in any case the returned partition list is incomplete (i.e. missing
> partitions that existed before, perhaps due to temporary ZK / broker
> downtime), then the state of the missing partitions is dropped and cannot be
> recovered anymore.
> In 1.3-SNAPSHOT, this is fixed by changes in FLINK-4280, so only 1.1 and 1.2
> is affected.
> We can backport some of the behavioural changes there to 1.1 and 1.2.
> Generally, we should not depend on the current partition list in Kafka when
> restoring, but just restore all previous state into the fetcher's state
> holders.
> This would therefore also require some checking on how the consumer threads /
> Kafka clients behave when its assigned partitions cannot be reached.
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