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https://issues.apache.org/jira/browse/FLINK-10122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16576169#comment-16576169
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ASF GitHub Bot commented on FLINK-10122:
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StefanRRichter opened a new pull request #6537: [FLINK-10122] KafkaConsumer
should use partitionable state over union state if partition discovery is not
active
URL: https://github.com/apache/flink/pull/6537
## What is the purpose of the change
KafkaConsumer store its offsets state always as union state. I think this is
only required in the case that partition discovery is active. For jobs with a
very high parallelism, the union state can lead to prohibitively expensive
deployments. For example, a job with 2000 source and a total of 10MB
checkpointed union state offsets state would have to ship ~ 2000 x 10MB = 20GB
of state. With partitionable state, it would have to ship ~10MB.
For now, I would suggest to go back to partitionable state in case that
partition discovery is not active. In the long run, I have some ideas for more
efficient partitioning schemes that would also work for active discovery.
As an additional step to support backwards compatibility and avoid state
blowup from the compatibility state, I also implemented FLINK-10121, so that
operator state can be removed from the backend.
Included also a hotfix that makes state assignment on the JM more memory
friendly by trying to allocate all collections with good sizes.
## Verifying this change
This change is already covered by existing tests.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (no)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (yes)
- The serializers: (no)
- The runtime per-record code paths (performance sensitive): (no)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes)
- The S3 file system connector: (no)
## Documentation
- Does this pull request introduce a new feature? (no)
- If yes, how is the feature documented? (not applicable)
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> KafkaConsumer should use partitionable state over union state if partition
> discovery is not active
> --------------------------------------------------------------------------------------------------
>
> Key: FLINK-10122
> URL: https://issues.apache.org/jira/browse/FLINK-10122
> Project: Flink
> Issue Type: Improvement
> Components: Kafka Connector
> Reporter: Stefan Richter
> Assignee: Stefan Richter
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.7.0
>
>
> KafkaConsumer store its offsets state always as union state. I think this is
> only required in the case that partition discovery is active. For jobs with a
> very high parallelism, the union state can lead to prohibitively expensive
> deployments. For example, a job with 2000 source and a total of 10MB
> checkpointed union state offsets state would have to ship ~ 2000 x 10MB =
> 20GB of state. With partitionable state, it would have to ship ~10MB.
> For now, I would suggest to go back to partitionable state in case that
> partition discovery is not active. In the long run, I have some ideas for
> more efficient partitioning schemes that would also work for active discovery.
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