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https://issues.apache.org/jira/browse/HBASE-15950?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15315224#comment-15315224
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Enis Soztutar commented on HBASE-15950:
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bq. Nope. JOL is GPL.
Thats a bummer. I was looking under
http://hg.openjdk.java.net/code-tools/jol/file/e8e889a8ae3d/src/license, and
saw BSD, but apparently not
http://hg.openjdk.java.net/code-tools/jol/file/e8e889a8ae3d/LICENSE.
In any case, we cannot use a JOL or a similar library to estimate byte[] or
other non-static class sizes since the parsing for each instance seems to be
pretty costly. I was thinking of getting the oops size and class size aligning
and change our ClassSize to use the dynamic information. Using Unsafe we can
still instantiate KV and other well-known objects and measure the actual base
sizes.
> 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
> Assignee: 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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