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https://issues.apache.org/jira/browse/HBASE-23349?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17015365#comment-17015365
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Lars Hofhansl commented on HBASE-23349:
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Minor nit: This is not lock coarsening. That was the failed I attempt I had to
reduce the frequency of taking memory barriers (the locks were almost never
contended), by pushing the locking up the stack into the region scanner.
[~ram_krish] and [~anoop.hbase] then came up with an actual solution :), but
that then required the reference counting.
Note that the numbers on HBASE-13082, where with the lock coarsening, not with
reference counting.
At this point my concern is just about correctness and the issues we have seen
with reference counting. It is generally very hard to retrofit reference
counting into a large, complex system. Ram and Anoop did an awesome job!
Perhaps HBase is just too complex to add this reliably.
> Low refCount preventing archival of compacted away files
> --------------------------------------------------------
>
> Key: HBASE-23349
> URL: https://issues.apache.org/jira/browse/HBASE-23349
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 3.0.0, 2.3.0, 1.6.0
> Reporter: Viraj Jasani
> Assignee: Viraj Jasani
> Priority: Major
> Fix For: 3.0.0, 2.3.0, 1.6.0
>
>
> We have observed that refCount on compacted away store files as low as 1 is
> prevent archival.
> {code:java}
> regionserver.HStore - Can't archive compacted file
> hdfs://{{root-dir}}/hbase/data/default/t1/12a9e1112e0371955b3db8d3ebb2d298/cf1/73b72f5ddfce4a34a9e01afe7b83c1f9
> because of either isCompactedAway=true or file has reference,
> isReferencedInReads=true, refCount=1, skipping for now.
> {code}
> We should come up with core code (run as part of discharger thread)
> gracefully resolve reader lock issue by resetting ongoing scanners to start
> pointing to new store files instead of compacted away store files.
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