RainerMatthiasS opened a new pull request, #23239:
URL: https://github.com/apache/flink/pull/23239
## Contribution Checklist
- `Pending:` Make sure that the change passes the automated tests, i.e.,
`mvn clean verify` passes. You can set up Azure Pipelines CI to do that
following [this
guide](https://cwiki.apache.org/confluence/display/FLINK/Azure+Pipelines#AzurePipelines-Tutorial:SettingupAzurePipelinesforaforkoftheFlinkrepository).
## What is the purpose of the change
Avoids a known flaw in Stream.flatMap, see
https://bugs.openjdk.org/browse/JDK-8267359. Avoids potential OOM Error for
keyed state with many keys when reading them with state processor api.
## Brief change log
- replaced the original implementation of MultiStateKeyIterator with a
Java-Stream-free implementation.
- this fixes a known flaw in Stream.flatMap which leads to complete
enumeration of inner iterator
and buffering of all elements with potential for a OOM error for state
with many keys
- manual implementation of nested iterator avoids this problem
## Verifying this change
This change adds a tests
MultiStateKeyIteratorTest#testIteratorPullsSingleKeyFromAllDescriptors that
fails with the previous implementation and succeeds with the new implementation.
## 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)`: no
- The serializers: no
- The runtime per-record code paths (performance sensitive): no
- new code should be marginally faster (not verified)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? no
- If yes, how is the feature documented? JavaDocs
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
