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From "Anoop Sam John (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16438) Create a cell type so that chunk id is embedded in it
Date Mon, 27 Mar 2017 09:15:41 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15942903#comment-15942903

Anoop Sam John commented on HBASE-16438:

I dont think Soft ref can be used.  Once the CSLM is converted to CellChunkMap, we dont have
any hard refs to Chunks from any where (Cells are gone).  Now the ChunkMap contain chunkId
and offset , length info.  Now assume a GC picked and removed these chunks (Ya there are no
hard refs to it), and after a read comes and we want to read back that Cell, what to do? !!!!

Ok if u also think CellChunkMap should be better used by off heap usage, can we say CellChunkMap
to be used along with off heap MSLAB pool usage only?  In case of off heap MSLAB all chunks
will get pooled. There wont be any on demand chunk creation.  So we will keep this  id vs
chunk info in map iff CellChunkMap is in place and so off heap MSLAB pool in place? 
Any way the above mentioned use case ideally should not use MSLAB pool at all.

> Create a cell type so that chunk id is embedded in it
> -----------------------------------------------------
>                 Key: HBASE-16438
>                 URL: https://issues.apache.org/jira/browse/HBASE-16438
>             Project: HBase
>          Issue Type: Sub-task
>    Affects Versions: 2.0.0
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>         Attachments: HBASE-16438_1.patch, HBASE-16438_3_ChunkCreatorwrappingChunkPool.patch,
HBASE-16438_4_ChunkCreatorwrappingChunkPool.patch, HBASE-16438.patch, MemstoreChunkCell_memstoreChunkCreator_oldversion.patch,
> For CellChunkMap we may need a cell such that the chunk out of which it was created,
the id of the chunk be embedded in it so that when doing flattening we can use the chunk id
as a meta data. More details will follow once the initial tasks are completed. 
> Why we need to embed the chunkid in the Cell is described by [~anastas] in this remark
over in parent issue https://issues.apache.org/jira/browse/HBASE-14921?focusedCommentId=15244119&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15244119

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