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https://issues.apache.org/jira/browse/BEAM-1612?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15907069#comment-15907069
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Aljoscha Krettek commented on BEAM-1612:
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I think what we could do is keep state/state updates in in-memory data
structures and only on commit (which is either by time or volume, i.e. how many
elements) we manifest these changes, which are a diff to the changes we keep in
Flink state, to Flink state. This would not make the changes durable, that only
happens when the next Flink checkpoint succeeds.
What do you think?
By the way, a Flink checkpoint can also fail, so if we committed right before
checkpointing we would still not have any guarantees of this actually
succeeding.
> Support real Bundle in Flink runner
> -----------------------------------
>
> Key: BEAM-1612
> URL: https://issues.apache.org/jira/browse/BEAM-1612
> Project: Beam
> Issue Type: Improvement
> Components: runner-flink
> Reporter: Jingsong Lee
> Assignee: Jingsong Lee
>
> The Bundle is very important in the beam model. Users can use the bundle to
> flush buffer, can reuse many heavyweight resources in a bundle. Most IO
> plugins use the bundle to flush.
> Moreover, FlinkRunner can also use Bundle to reduce access to the FlinkState,
> such as first placed in JavaHeap, flush into RocksDbState when invoke
> finishBundle , this can reduce the number of serialization.
> But now FlinkRunner calls the finishBundle every processElement. We need
> support real Bundle.
> I think we can have the following implementations:
> 1.Invoke finishBundle and next startBundle in {{snapshot}} of Flink. But
> sometimes this "Bundle" maybe too big. This depends on the user's checkpoint
> configuration.
> 2.Manually control the size of the bundle. The half-bundle will be flushed to
> a full-bundle by count or eventTime or processTime or {{snapshot}}. We do not
> need to wait, just call the startBundle and finishBundle at the right time.
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