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https://issues.apache.org/jira/browse/HBASE-11425?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14047590#comment-14047590
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ramkrishna.s.vasudevan commented on HBASE-11425:
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bq.Currently we copy the block cache bytes onheap to guard against the blocks
being evicted out from under us. We'll do reference counting?
I think this is one major area where we may have to work. If a block is
currently getting scanned set a reference and do not evict them. On what basis
should we select the next block that can be evicted ? Need to do some more
analysis on this.
Interesting!!.
> Cell/DBB end-to-end on the read-path
> ------------------------------------
>
> Key: HBASE-11425
> URL: https://issues.apache.org/jira/browse/HBASE-11425
> Project: HBase
> Issue Type: Umbrella
> Components: regionserver, Scanners
> Affects Versions: 0.99.0
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
>
> Umbrella jira to make sure we can have blocks cached in offheap backed cache.
> In the entire read path, we can refer to this offheap buffer and avoid onheap
> copying.
> The high level items I can identify as of now are
> 1. Avoid the array() call on BB in read path.. (This is there in many
> classes. We can handle class by class)
> 2. Support Buffer based getter APIs in cell. In read path we will create a
> new Cell with backed by BB. Will need in CellComparator, Filter (like SCVF),
> CPs etc.
> 3. Avoid KeyValue.ensureKeyValue() calls in read path - This make byte copy.
> 4. Remove all CP hooks (which are already deprecated) which deal with KVs.
> (In read path)
> Will add subtasks under this.
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