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https://issues.apache.org/jira/browse/HBASE-21921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16829006#comment-16829006
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Zheng Hu commented on HBASE-21921:
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Uploaded the intial patch.v01, not the final version. expose some metrics in
ByteBuffAllocator, will show the promotion in in region server web page , maybe
also JMX.
> Notify users if the ByteBufAllocator is always allocating ByteBuffers from
> heap which means the increacing GC pressure
> ----------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-21921
> URL: https://issues.apache.org/jira/browse/HBASE-21921
> Project: HBase
> Issue Type: Sub-task
> Reporter: Zheng Hu
> Assignee: Zheng Hu
> Priority: Minor
> Attachments: HBASE-21921.HBASE-21879.v01.patch
>
>
> As the javadoc of ByteBuffAllocator says:
> {code}
> There's possible that the desired memory size is large than ByteBufferPool
> has, we'll downgrade to allocate ByteBuffers from heap which meaning the GC
> pressure may increase again. Of course, an better way is increasing the
> ByteBufferPool size if we detected this case.
> {code}
> So I think we need some messages to remind the user that an larger
> ByteBufferPool size may be better if the allocator allocate ByteBuffer from
> heap frequently.
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