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https://issues.apache.org/jira/browse/HBASE-20542?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16526371#comment-16526371
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Mike Drob commented on HBASE-20542:
-----------------------------------
bq. I don't understand why I get these java warnings, they are related to a
test that has nothing to do with this issue, and was not changed by this patch
!?!
you're right, they should be unrelated. I'll look into them. Please ignore them
this time :)
> Better heap utilization for IMC with MSLABs
> -------------------------------------------
>
> Key: HBASE-20542
> URL: https://issues.apache.org/jira/browse/HBASE-20542
> Project: HBase
> Issue Type: Sub-task
> Reporter: Eshcar Hillel
> Assignee: Eshcar Hillel
> Priority: Major
> Attachments: HBASE-20542.branch-2.001.patch,
> HBASE-20542.branch-2.003.patch, HBASE-20542.branch-2.004.patch,
> HBASE-20542.branch-2.005.patch, HBASE-20542.master.003.patch, run.sh,
> workloada, workloadc, workloadx, workloady
>
>
> Following HBASE-20188 we realized in-memory compaction combined with MSLABs
> may suffer from heap under-utilization due to internal fragmentation. This
> jira presents a solution to circumvent this problem. The main idea is to have
> each update operation check if it will cause overflow in the active segment
> *before* it is writing the new value (instead of checking the size after the
> write is completed), and if it is then the active segment is atomically
> swapped with a new empty segment, and is pushed (full-yet-not-overflowed) to
> the compaction pipeline. Later on the IMC deamon will run its compaction
> operation (flatten index/merge indices/data compaction) in the background.
> Some subtle concurrency issues should be handled with care. We next elaborate
> on them.
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