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https://issues.apache.org/jira/browse/HBASE-15950?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Enis Soztutar updated HBASE-15950:
----------------------------------
    Release Note: Made the object/array header sizes to be CompressedOops aware 
and fixed object heap size calculations for important objects like KeyValue and 
ConcurrentSkipListMap and . For heap sizes up to 32GB, depending on average 
cell sizes and total memstore size, %10-50 reduction in memstore size and 
flushes and compactions might be observed. YMMV. Due to more tighter than 
before size estimates, total heap space is expected to be utilized more, 
slightly increasing the chance to get OOM if misconfigured. Set the environment 
property (not hbase-site.xml) "hbase.memorylayout.use.unsafe" to false to 
disable. 

> Fix memstore size estimates to be more tighter
> ----------------------------------------------
>
>                 Key: HBASE-15950
>                 URL: https://issues.apache.org/jira/browse/HBASE-15950
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Enis Soztutar
>            Assignee: Enis Soztutar
>             Fix For: 2.0.0
>
>         Attachments: Screen Shot 2016-06-02 at 8.48.27 PM.png, 
> hbase-15950-v0.patch
>
>
> 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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