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https://issues.apache.org/jira/browse/HBASE-15950?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15320566#comment-15320566
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Dave Latham commented on HBASE-15950:
-------------------------------------
This is good to do, but I think the warning in the release note likely needs to
be louder and that it should also go in upgrade notes for 2.0.
Something like:
The estimates of heap usage by the memstore have been made more accurate,
resulting in them dropping by 10-50% in practice. As a result, the actual heap
usage of the memstore before being flushed may increase by up to 100%. If
configured memory limits for the region server had been tuned based on observed
usage, this change could result in worse GC behavior or even OutOfMemory errors.
Should we consider pairing this change with a reduction in the default memstore
usage percent?
> 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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