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https://issues.apache.org/jira/browse/MAPREDUCE-5176?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13662339#comment-13662339
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Karthik Kambatla commented on MAPREDUCE-5176:
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bq. what we envisioned for mapreduce is that and advanced user that have a
stateful UDF can mark it as @Preemptable and override the default save to
checkpoint logic to include the portion of state he/she cares about.
While that is perfectly fine for a first draft solution, a user might prefer to
get feedback when they annotate @Preemptable without fully understanding the
consequences. Assuming @Stateless is also added, the preemption code can warn
the user that they have annotated @Preemptable without @Stateless and that they
are expected to implement/override the checkpoint logic. Thoughts?
> Preemptable annotations (to support preemption in MR)
> -----------------------------------------------------
>
> Key: MAPREDUCE-5176
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5176
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: mrv2
> Reporter: Carlo Curino
> Assignee: Carlo Curino
> Attachments: MAPREDUCE-5176.1.patch, MAPREDUCE-5176.patch
>
>
> Proposing a patch that introduces a new annotation @Preemptable that
> represents to the framework property of user-supplied classes (e.g., Reducer,
> OutputCommiter). The intended semantics is that a tagged class is safe to be
> preempted between invocations.
> (this is in spirit similar to the Output Contracts of [Nephele/PACT |
> https://stratosphere.eu/sites/default/files/papers/ComparingMapReduceAndPACTs_11.pdf])
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