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https://issues.apache.org/jira/browse/HBASE-13926?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14591234#comment-14591234
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Anoop Sam John commented on HBASE-13926:
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Sure Ram. Thanks.
> Close the scanner only after Call#setResponse
> ---------------------------------------------
>
> Key: HBASE-13926
> URL: https://issues.apache.org/jira/browse/HBASE-13926
> Project: HBase
> Issue Type: Sub-task
> Components: regionserver, Scanners
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Fix For: 2.0.0
>
> Attachments: HBASE-13926.patch
>
>
> This is for HBASE-12295. We will be delivering cells directly from shared
> cache memory. HBASE-12295 adds a ref count based prevention mechanism to
> avoid block eviction, when that memory area in use by scanners. We will
> decrement ref count at scanner close. The memory area will be in use till a
> cellblock is created or PB scan reply message is built. So we can delay the
> close of the scanner until the response is set for the scanner Call. This is
> done via a RpcCallback way. The callback is set on Call at scan time. Once
> the setResponse is done, the Call will execute the RpcCallback.
> This jira also adds a facility to do some cleanup/close during the course of
> scan. Scan from client makes many RPCs fetching N rows each time. Only at the
> end the scanner close will happen. We will add a new batchClose() facility
> with which we can do any cleanup after every rpc call is executed and rows
> fetched for return.
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