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https://issues.apache.org/jira/browse/HBASE-15950?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15313550#comment-15313550
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Enis Soztutar commented on HBASE-15950:
---------------------------------------
This is the estimates with using REFERENCE size as 4 bytes assuming compressed
pointers:
{code}
memstore size=3.4 G
memstore KV size=1.3 G
memstore KV bytes size=915.5 M
memstore CSLM size=1.1 G
{code}
25% more space for memstore does not sound bad. And the numbers are still not
close enough.
If instead we use {{-XX:-UseCompressedOops}}, the numbers from profiling comes
up as:
{code}
memstore size=3.4 G
memstore KV size=1.12 G
memstore KV bytes size=860 M
memstore CSLM size=1.12G + 572M
{code}
Still some differences.
> We are grossly overestimating the memstore size
> -----------------------------------------------
>
> Key: HBASE-15950
> URL: https://issues.apache.org/jira/browse/HBASE-15950
> Project: HBase
> Issue Type: Bug
> Reporter: Enis Soztutar
> Fix For: 2.0.0
>
> Attachments: Screen Shot 2016-06-02 at 8.48.27 PM.png
>
>
> While testing something else, I was loading a region with a lot of data.
> Writing 30M cells in 1M rows, with 1 byte values.
> The memstore size turned out to be estimated as 4.5GB, while with the JFR
> profiling I can see that we are using 2.8GB for all the objects in the
> memstore (KV + KV byte[] + CSLM.Node + CSLM.Index).
> This obviously means that there is room in the write cache that we are not
> effectively using.
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