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https://issues.apache.org/jira/browse/FLINK-6014?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15932493#comment-15932493
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ASF GitHub Bot commented on FLINK-6014:
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Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/3524
Can you give me some background why you want to make also
`PendingCheckpoint` register its state immediately (and not only upon
completion)?
I see no problem with that, just want to double check whether we are
changing the assumption from the original design doc, where you suggested that
shared state can only be referenced by another checkpoint, if it is already
part of a committed checkpoint.
> Allow the registration of state objects in checkpoints
> ------------------------------------------------------
>
> Key: FLINK-6014
> URL: https://issues.apache.org/jira/browse/FLINK-6014
> Project: Flink
> Issue Type: Sub-task
> Components: State Backends, Checkpointing
> Reporter: Xiaogang Shi
> Assignee: Xiaogang Shi
>
> This issue is the very first step towards incremental checkpointing. We
> introduce a new state handle named {{CompositeStateHandle}} to be the base of
> the snapshots taken by task components. Known implementation may include
> {{KeyedStateHandle}} (for {{KeyedStateBackend}}s), {{SubtaskState}} (for
> subtasks, splits of {{JobVertex}}) and {{TaskState}} (for {{JobVertex}}s).
> Each {{CompositeStateHandle}} is composed of a collection of {{StateObject}s.
> It should register all its state objects in {{StateRegistry}} when its
> checkpoint is added into {{CompletedCheckpointStore}} (i.e., a pending
> checkpoint completes or a complete checkpoint is reloaded in the recovery).
> When a completed checkpoint is moved out of the {{CompletedCheckpointStore}},
> we should not simply discard all state objects in the checkpoint. With the
> introduction of incremental checkpointing, a {{StateObject}} may be
> referenced by different checkpoints. We should unregister all the state
> objects contained in the {{StateRegistry}} first. Only those state objects
> that are not referenced by any checkpoint can be deleted.
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