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https://issues.apache.org/jira/browse/HBASE-27805?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zheng Wang resolved HBASE-27805.
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Resolution: Fixed
> The chunk created by mslab may cause memory fragement and lead to fullgc
> ------------------------------------------------------------------------
>
> Key: HBASE-27805
> URL: https://issues.apache.org/jira/browse/HBASE-27805
> Project: HBase
> Issue Type: Improvement
> Components: documentation
> Reporter: Zheng Wang
> Assignee: Zheng Wang
> Priority: Major
> Attachments: chunksize-2047k.png, chunksize-2048k-fullgc.png
>
>
> The default size of chunk is 2m, when we use G1, if heapRegionSize equals 4m,
> these chunks are allocated as humongous objects, exclusively allocating one
> region, then the remaining 2m become memory fragement.
> Lots of memory fragement may lead to fullgc even if the percent of used heap
> not high enough.
> I have tested to reduce the chunk size to 2047k(2m-1k, a bit lesser than half
> of heapRegionSize), there was no repeat of the above.
> BTW, in G1, humongous objects are objects larger or equal the size of half a
> region, and the heapRegionSize is automatically calculated based on the heap
> size parameter if not explicitly specified.
>
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