rkhachatryan opened a new pull request #12292:
URL: https://github.com/apache/flink/pull/12292
## What is the purpose of the change
If Unaligned checkpoints are enabled, channel state is written as state
handles. Each channel has a handle and each such handle references the same
underlying `streamStateHandle` (this is done to have a single file per subtask).
But, if the state is less then `state.backend.fs.memory-threshold`, the data
is sent directly to JM as a byteStreamHandle. This causes each channel state
handle to hold the whole subtask state.
This PR solves this by extracting relevant potions of the underlying handles
if they are `byteStreamHandle`s.
Another approach would be to move the underlying state handle one level up
(`OperatorSubtaskState`) and not store references to it in
`channelStateHandles`. It would be more effective (less data duplication) but
also more error-prone (implicit structure), less flexible (re-scaling), and
require more changes.
## Verifying this change
This change is already covered by existing tests, such as:
- `ChannelStateCheckpointWriterTest.testRecordingOffsets` (the test was
corrected)
- `ChannelPersistenceITCase`
## 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
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn/Mesos, 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? not applicable
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