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https://issues.apache.org/jira/browse/FLINK-28838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17582188#comment-17582188
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Aitozi edited comment on FLINK-28838 at 8/20/22 10:35 AM:
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Hi [~renqs] do you have any further comments? If no objection, I'd like to open 
a PR for this.


was (Author: aitozi):
Hi [~renqs] do you have any further comments, If no objection, I'd like to open 
a PR for this ?

> Avoid to notify the elementQueue consumer when the fetch result is empty
> ------------------------------------------------------------------------
>
>                 Key: FLINK-28838
>                 URL: https://issues.apache.org/jira/browse/FLINK-28838
>             Project: Flink
>          Issue Type: Improvement
>          Components: Connectors / Common
>    Affects Versions: 1.15.0, 1.15.1
>            Reporter: Aitozi
>            Priority: Major
>             Fix For: 1.16.0
>
>         Attachments: 20220805165441.jpg
>
>
> When using the new source api, I found that if the source has no data, it 
> still brings high cpu usage. 
> The reason behind this is that it will always return the 
> {{RecordsWithSplitIds}} from the {{splitReader.fetch}} in FetchTask and it 
> will be added to the elementQueue. It will make the consumer be notified to 
> wake up frequently.
> This causes the thread to keep busy to run and wake up, which leads to the 
> high sys and user cpu usage.
> I think not all the SplitReader#fetch will block until there is data, if it 
> returns immediately when there is no data, then this problem will happen



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