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https://issues.apache.org/jira/browse/FLINK-17122?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Flink Jira Bot updated FLINK-17122:
-----------------------------------
    Labels: stale-major  (was: )

I am the [Flink Jira Bot|https://github.com/apache/flink-jira-bot/] and I help 
the community manage its development. I see this issues has been marked as 
Major but is unassigned and neither itself nor its Sub-Tasks have been updated 
for 30 days. I have gone ahead and added a "stale-major" to the issue". If this 
ticket is a Major, please either assign yourself or give an update. Afterwards, 
please remove the label or in 7 days the issue will be deprioritized.


> Support InputSelectable and BoundedMultiInput operators with checkpointing
> --------------------------------------------------------------------------
>
>                 Key: FLINK-17122
>                 URL: https://issues.apache.org/jira/browse/FLINK-17122
>             Project: Flink
>          Issue Type: Improvement
>          Components: Runtime / Checkpointing, Runtime / Network
>    Affects Versions: 1.9.2, 1.10.0
>            Reporter: Piotr Nowojski
>            Priority: Major
>              Labels: stale-major
>
> Currently when user defined some {{InputSelectable}} or {{BoundedMultiInput}} 
> operators, checkpointing is not supported. Main problem is the that 
> combination of {{InputSelectable}} and barrier alignment can lead to 
> deadlocks (checkpoint barrier stuck on not selected channel). 
> Problem could be somehow mitigated via unaligned checkpoints (FLINK-14551), 
> but not fully. Even with unaligned checkpoints, checkpoint barriers can be 
> stuck in the job graph if there is a {{flatMap}} operator (or non {{flatMap}} 
> operator but if records are spanning multiple buffers), blocked in the middle 
> of processing by some down stream input selection. In such case we are not 
> able to perform unaligned checkpoint.
> Potential solution could be using persistent communication channels or 
> detecting before mentioned situations and avoid the dead lock by spilling 
> excess data.
> As most of the problems are with input selections that are randomly flipping, 
> there might be some partial solution for more trivial cases, like reading one 
> side of an input fully before the other.



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