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https://issues.apache.org/jira/browse/HBASE-27650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17694719#comment-17694719
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Hudson commented on HBASE-27650:
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Results for branch branch-2.5
[build #307 on
builds.a.o|https://ci-hbase.apache.org/job/HBase%20Nightly/job/branch-2.5/307/]:
(/) *{color:green}+1 overall{color}*
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details (if available):
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report|https://ci-hbase.apache.org/job/HBase%20Nightly/job/branch-2.5/307/General_20Nightly_20Build_20Report/]
(/) {color:green}+1 jdk8 hadoop2 checks{color}
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(/) {color:green}+1 jdk8 hadoop3 checks{color}
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(/) {color:green}+1 source release artifact{color}
-- See build output for details.
(/) {color:green}+1 client integration test{color}
> Merging empty regions corrupts meta cache
> -----------------------------------------
>
> Key: HBASE-27650
> URL: https://issues.apache.org/jira/browse/HBASE-27650
> Project: HBase
> Issue Type: Bug
> Reporter: Bryan Beaudreault
> Assignee: Bryan Beaudreault
> Priority: Major
> Labels: patch-available
> Fix For: 2.6.0, 3.0.0-alpha-4, 2.4.17, 2.5.4
>
>
> Let's say you have three regions with start keys A, B, C and all are cached
> in the meta cache. Region B is empty and not getting any requests, and all 3
> regions are merged together. The new merged region has start key A.
> A user submits a request for row C1, which would previously have gone to
> region C. That region no longer exists, so the MetaCache returns region C,
> the request goes out to the server which throws NotServingRegionException.
> That region C is now removed from the cache, and meta is scanned. The meta
> scan returns the newly merged region A, which is cached into the MetaCache.
> So now we have a MetaCache where A has been updated with the newly merged
> RegionInfo, B still exists with the old/deleted RegionInfo, and C has been
> removed.
> A user submits a request for row C1 again. This _should_ go to region A, but
> we do cache.floorEntry(C1) which returns the old but still cached region B.
> We have checks in MetaCache which validate the RegionInfo.getEndKey() against
> the requested row, and that validation fails because C1 is beyond the endkey
> of the old region. The cached region B result is ignored and cache returns
> null. Meta is scanned, and returns the new region A, which is cached again.
> Requests to rows C1+ will still succeed... but they will always require a
> meta scan because the meta cache will always return that old region B which
> is invalid and doesn't contain the C1+ rows.
> Currently, the only way this will ever resolve is if a request is sent to
> region B, which will cause a NotServingRegionException which will finally
> clear region B from the cache. At that point, requests for C1+ will properly
> get resolved to region A in the cache.
> I've created a reproducible test case here:
> [https://gist.github.com/bbeaudreault/c82ff9f8ad0b9424eb987483ede35c12]
> This problem affects both AsyncTable and branch-2's Table.
>
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