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https://issues.apache.org/jira/browse/HBASE-21436?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16677818#comment-16677818
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Anoop Sam John commented on HBASE-21436:
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The 2 MB chunk size is configurable. It will be better to reduce this in ur
case.
As per the better accounting, I agree with Allan. I also thought it similar
lines in the past. Yes we need a better accounting.
> Getting OOM frequently if hold many regions
> --------------------------------------------
>
> Key: HBASE-21436
> URL: https://issues.apache.org/jira/browse/HBASE-21436
> Project: HBase
> Issue Type: Improvement
> Components: regionserver
> Affects Versions: 1.4.8, 2.1.1, 2.0.2
> Reporter: Zephyr Guo
> Priority: Major
> Attachments: HBASE-21436-UT.patch
>
>
> Recently, some feedback reached me from a customer which complains about
> NotServingRegionException thrown out at intevals. I examined his cluster and
> found there were quite a lot of OOM logs there but throughtput is in quite
> low level. In this customer's case, each RS has 3k regions and heap size of
> 4G. I dumped heap when OOM took place, and found that a lot of Chunk objects
> (counts as much as 1700) was there.
> Eventually, piecing all these evidences together, I came to the conclusion
> that:
> * The root cause is that global flush is triggered by size of all memstores,
> rather than size of all chunks.
> * A chunk is always allocated for each region, even we only write a few data
> to the region.
> And in this case, a total of 3.4G memory was consumed by 1700 chunks,
> although throughput is very low.
> Although 3K regions is too much for RS with 4G memory, it is still wise to
> improve RS stability in such scenario (In fact, most customers buy a small
> size HBase on cloud side).
>
> I provide a patch (only contain UT) to reproduce this case (just send a
> batch).
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