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From "Jonathan Lawlor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13090) Progress heartbeats for long running scanners
Date Fri, 06 Mar 2015 19:40:40 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13090?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14350782#comment-14350782
] 

Jonathan Lawlor commented on HBASE-13090:
-----------------------------------------

bq. Why does RsRpcServices have to be involved? Could remaining scan time not be up in RegionScanner?

I think RsRpcServices needs to be involved because it has the global view of when the scan
started. A particular call to RegionScanner#nextRaw may not necessarily cause a timeout, but
multiple calls to RegionScanner#nextRaw must be made in order to form the ScanResponse. In
other words, a timeout may not be caused by a single call to RegionScanner#nextRaw but rather
the accumulated time of all calls necessary to form the ScanResponse.

> Progress heartbeats for long running scanners
> ---------------------------------------------
>
>                 Key: HBASE-13090
>                 URL: https://issues.apache.org/jira/browse/HBASE-13090
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Andrew Purtell
>
> It can be necessary to set very long timeouts for clients that issue scans over large
regions when all data in the region might be filtered out depending on scan criteria. This
is a usability concern because it can be hard to identify what worst case timeout to use until
scans are occasionally/intermittently failing in production, depending on variable scan criteria.
It would be better if the client-server scan protocol can send back periodic progress heartbeats
to clients as long as server scanners are alive and making progress.
> This is related but orthogonal to streaming scan (HBASE-13071). 



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