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https://issues.apache.org/jira/browse/FLINK-19701?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17216439#comment-17216439
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Yun Gao commented on FLINK-19701:
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[~AHeise] [~pnowojski] Could you have a look at whether this is truly a problem
? I test this case manually by blocking the barriers from the upstream tasks
and it seems to be exist.
> Unaligned Checkpoint might misuse the number of buffers to persist from the
> previous barrier
> --------------------------------------------------------------------------------------------
>
> Key: FLINK-19701
> URL: https://issues.apache.org/jira/browse/FLINK-19701
> Project: Flink
> Issue Type: Bug
> Components: Runtime / Checkpointing
> Affects Versions: 1.12.0
> Reporter: Yun Gao
> Priority: Major
>
> Current CheckpointUnaligner interacts with RemoteInputChannel to persisting
> the input buffers. However, based the current implementation it seems if we
> have the following case:
> {code:java}
> 1. There are 3 input channels.
> 2. Input channel 0 received barrier 1, and processed barrier 1 to start
> checkpoint 1.
> 3. Input channel 1 received barrier 1, and processed barrier 1. Now the state
> of input channel persister becomes BARRIER_RECEIVED and
> numBuffersOvertaken(channel 1) = n_1.
> 4. However, input 2 received nothing and the checkpoint expired, new
> checkpoint is trigger.
> 5. Input channel 0 received barrier 2, checkpoint 1 is deserted and
> checkpoint 2 is started. However, in this case the state of the input
> channels are not cleared. Thus now channel 1 is still BARRIER_RECEIVED and
> numBuffersOvertaken(channel 1) = n_1. Then channel 1 would only persist n_1
> buffers in the channel for the new checkpoint 2.
> {code}
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