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https://issues.apache.org/jira/browse/FLINK-8533?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16363764#comment-16363764
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ASF GitHub Bot commented on FLINK-8533:
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Github user tillrohrmann commented on the issue:
https://github.com/apache/flink/pull/5427
@EronWright, you're right that on initial submission we don't call
`restoreLatestCheckpointedState` in the old code. With Flip-6 this will be the
case. See #5444.
The underlying assumption to make this work, though, is that a user won't
submit a new job with the a job id to a cluster with a cluster id for which
ZooKeeper already contains persisted checkpoints from a previous run. So either
the cluster id or the job id must be different.
I think so far, when using the Flink client this should be the case.
However, when generating the `JobGraph` yourself and keeping it around to
submit it to a standalone cluster, then this assumption will break because both
the `JobID` and the cluster id will be the same.
> Support MasterTriggerRestoreHook state reinitialization
> -------------------------------------------------------
>
> Key: FLINK-8533
> URL: https://issues.apache.org/jira/browse/FLINK-8533
> Project: Flink
> Issue Type: Bug
> Components: State Backends, Checkpointing
> Affects Versions: 1.3.0
> Reporter: Eron Wright
> Assignee: Eron Wright
> Priority: Major
>
> {{MasterTriggerRestoreHook}} enables coordination with an external system for
> taking or restoring checkpoints. When execution is restarted from a
> checkpoint, {{restoreCheckpoint}} is called to restore or reinitialize the
> external system state. There's an edge case where the external state is not
> adequately reinitialized, that is when execution fails _before the first
> checkpoint_. In that case, the hook is not invoked and has no opportunity to
> restore the external state to initial conditions.
> The impact is a loss of exactly-once semantics in this case. For example, in
> the Pravega source function, the reader group state (e.g. stream position
> data) is stored externally. In the normal restore case, the reader group
> state is forcibly rewound to the checkpointed position. In the edge case
> where no checkpoint has yet been successful, the reader group state is not
> rewound and consequently some amount of stream data is not reprocessed.
> A possible fix would be to introduce an {{initializeState}} method on the
> hook interface. Similar to {{CheckpointedFunction::initializeState}}, this
> method would be invoked unconditionally upon hook initialization. The Pravega
> hook would, for example, initialize or forcibly reinitialize the reader group
> state.
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