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https://issues.apache.org/jira/browse/FLINK-16057?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Piotr Nowojski updated FLINK-16057:
-----------------------------------
Component/s: (was: Runtime / Task)
API / DataStream
> Performance regression in ContinuousFileReaderOperator
> ------------------------------------------------------
>
> Key: FLINK-16057
> URL: https://issues.apache.org/jira/browse/FLINK-16057
> Project: Flink
> Issue Type: Bug
> Components: API / DataStream
> Affects Versions: 1.11.0
> Reporter: Roman Khachatryan
> Priority: Blocker
>
> After switching to a single-threaded execution model performance regression
> was expected to be about 15-20% (benchmarked in November).
> After merging it turned out to be about 50%.
>
>
> One reason is that the chaining strategy isn't set by default in CFRO factory.
> Without this even reading and outputting all records of a split in a single
> mail action doesn't reverse the regression (only about half).
> However, with strategy set AND batching enabled fixes the regression
> (starting from batch size 6).
>
> Though batching can't be used in practice because it can significantly delay
> checkpointing.
> Another approach would be to process one record and the repeat until
> defaultMailboxActionAvailable OR haveNewMail.
> This reverses regression and even improves the performance by about 50%
> compared to the old version.
>
> The final solution could also be FLIP-27.
>
> Other things tried (didn't help):
> * CFRO rework without subsequent commits (removing checkpoint lock)
> * different batch sizes, including the whole split, without chaining
> strategy fixed - partial improvement only
> * disabling close
> * disabling checkpointing
> * disabling output (serialization)
> * using LinkedList instead of PriorityQueue
>
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