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https://issues.apache.org/jira/browse/CASSANDRA-16681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17544288#comment-17544288
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Piotr Kolaczkowski commented on CASSANDRA-16681:
------------------------------------------------

> What JMM peculiarities are you worried about?

The fact this is a non-atomic data structure that supports both writes and 
reads already puts it in territory of "lockless concurrent data structures", 
which is by definition hard and risky.

E.g. this structure has a counter of non-null fields. When either adding or 
removing it updates the fields and updates the counter. How do you ensure the 
other threads see a consistent state? Not sure, but I'm afraid at least some 
CAS would be needed somewhere. 

I'm not saying it cannot be done, but IMHO keeping LocalPool really thread 
local avoids a lot of complexity. 

 

> org.apache.cassandra.utils.memory.LongBufferPoolTest - tests are flaky
> ----------------------------------------------------------------------
>
>                 Key: CASSANDRA-16681
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-16681
>             Project: Cassandra
>          Issue Type: Bug
>          Components: CI
>            Reporter: Ekaterina Dimitrova
>            Assignee: Piotr Kolaczkowski
>            Priority: Normal
>             Fix For: 3.11.x, 4.0.x, 4.x
>
>         Attachments: 0001-Fix-memoryInUse-counter-in-BufferPool.patch, 
> 0002-Multiple-fixes-in-BufferPool-and-LongBufferPoolTest.patch
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> Jenkins history:
> [https://jenkins-cm4.apache.org/job/Cassandra-4.0/50/testReport/junit/org.apache.cassandra.utils.memory/LongBufferPoolTest/testPoolAllocateWithRecyclePartially/history/]
> Fails being run in a loop in CircleCI:
> https://app.circleci.com/pipelines/github/ekaterinadimitrova2/cassandra/844/workflows/945011f4-00ac-4678-89f6-5c0db0a40169/jobs/5008
>  



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