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https://issues.apache.org/jira/browse/FLINK-31610?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17706028#comment-17706028
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Anton Kalashnikov commented on FLINK-31610:
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??Consider such a scenario, the CurrentPoolSize = 5,
numOfRequestedMemorySegments = 7, maxOverdraftBuffersPerGate = 2. If
numberOfRequestedOverdraftMemorySegments = 0, then 2 buffers can be requested
now. If the counter for requested overdraft-buffers is removed, is it still
allowed to request buffers in this case, and if so, how many buffers can be
requested at most???
Do I understand correctly that this scenario is possible only when it had been
requested 7 buffers and after that CurrentPoolSize was decreased(vis
setNumBuffers) to 5? We need to think about how important/relevant this
scenario is
> Refactoring of LocalBufferPool
> ------------------------------
>
> Key: FLINK-31610
> URL: https://issues.apache.org/jira/browse/FLINK-31610
> Project: Flink
> Issue Type: Improvement
> Components: Runtime / Network
> Affects Versions: 1.17.0
> Reporter: Anton Kalashnikov
> Priority: Major
>
> FLINK-31293 bug highlighted the issue with the internal mutual consistency of
> different fields in LocalBufferPool. ex.:
> - `numberOfRequestedOverdraftMemorySegments`
> - `numberOfRequestedMemorySegments`
> - `availableMemorySegment`
> - `currentPoolSize`
> Most of the problem was fixed already(I hope) but it is a good idea to
> reorganize the code in such a way that all invariants between all fields
> inside will be clearly determined and difficult to break.
> As one example I can propose getting rid of
> numberOfRequestedOverdraftMemorySegments and using existing
> numberOfRequestedMemorySegments instead. That means:
> - the pool will be available when `!availableMemorySegments.isEmpty() &&
> unavailableSubpartitionsCount == 0`
> - we don't request a new `ordinary` buffer when
> `numberOfRequestedMemorySegments >= currentPoolSize` but we request the
> overdraft buffer instead
> - `setNumBuffers` should work automatically without any changes
> I think we can come up with a couple of such improvements to simplify the
> code.
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