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https://issues.apache.org/jira/browse/FLINK-16556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17395709#comment-17395709
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Liebing Yu commented on FLINK-16556:
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I have a question: why more changes are needed to use parallel source.
As for whether the Random instance needs to be serialized, I think it has no
effect on the calculation of the entire example from a functional point of
view. But from the perspective of the completeness of the example, I think it
is necessary, because Random is a stateful field, and we should persist its
state in a stateful operator.
> TopSpeedWindowing should implement checkpointing for its source
> ---------------------------------------------------------------
>
> Key: FLINK-16556
> URL: https://issues.apache.org/jira/browse/FLINK-16556
> Project: Flink
> Issue Type: Bug
> Components: Examples
> Affects Versions: 1.10.0
> Reporter: Nico Kruber
> Assignee: Liebing Yu
> Priority: Minor
> Labels: auto-deprioritized-major, starter
>
> {\{org.apache.flink.streaming.examples.windowing.TopSpeedWindowing.CarSource}}
> does not implement checkpointing of its state, namely the current speeds and
> distances per car. The main problem with this is that the window trigger only
> fires if the new distance has increased by at least 50 but after restore, it
> will be reset to 0 and could thus not produce output for a while.
>
> Either the distance calculation could use {{Math.abs}} or the source needs
> proper checkpointing. Optionally with allowing the number of cars to
> increase/decrease.
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