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https://issues.apache.org/jira/browse/HBASE-20542?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16539767#comment-16539767
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Duo Zhang commented on HBASE-20542:
-----------------------------------
Thanks. Let's see how it works.
> 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
> Components: in-memory-compaction
> Reporter: Eshcar Hillel
> Assignee: Eshcar Hillel
> Priority: Major
> Fix For: 3.0.0, 2.2.0
>
> Attachments: HBASE-20542-addendum.master.005.patch,
> 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, HBASE-20542.master.005-addendum.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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