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https://issues.apache.org/jira/browse/HBASE-15102?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ashu Pachauri updated HBASE-15102:
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Attachment: HBASE-15102-V0.patch
V0: Choose a conservative approach while decreasing memstore size by choosing
min size in the middle of high water and low water mark. The reason to choose
it in the middle rather than at the previous low water mark is that if we do
so, we will trigger too many flushes at once (because the low water mark will
also move down once we bring down the memstore size).
> HeapMemoryTuner can "overtune" memstore size and suddenly drop it into
> blocking zone
> ------------------------------------------------------------------------------------
>
> Key: HBASE-15102
> URL: https://issues.apache.org/jira/browse/HBASE-15102
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Affects Versions: 2.0.0, 1.2.0, 1.3.0, 1.2.1
> Reporter: Ashu Pachauri
> Assignee: Ashu Pachauri
> Priority: Critical
> Attachments: HBASE-15102-V0.patch
>
>
> DefaultHeapMemoryTuner often resets the maximum step size for tuning to 8% of
> total heap size. Often, when the size of memstore is to be decreased while
> tuning, the 8% tuning can suddenly drop the memstore size below the low water
> mark of the previous memstore size (which could potentially be the used size
> of the memstore)
> This is problematic because suddenly it blocks all the updates by suddenly
> causing a situation where memstore used size is above high water mark. This
> has a very bad performance impact on an otherwise fine HBase cluster.
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