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https://issues.apache.org/jira/browse/HBASE-30161?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18084176#comment-18084176
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Hudson commented on HBASE-30161:
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Results for branch branch-3
[build #571 on
builds.a.o|https://ci-hbase.apache.org/job/HBase%20Nightly/job/branch-3/571/]:
(/) *{color:green}+1 overall{color}*
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details (if available):
(/) {color:green}+1 general checks{color}
-- For more information [see general
report|https://ci-hbase.apache.org/job/HBase%20Nightly/job/branch-3/571/General_20Nightly_20Build_20Report/]
(/) {color:green}+1 jdk17 hadoop3 checks{color}
-- For more information [see jdk17
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> Add paginated, single-RPC RegionLocator.getRegionLocations(startKey, limit)
> API for bulk meta-cache warmup
> ----------------------------------------------------------------------------------------------------------
>
> Key: HBASE-30161
> URL: https://issues.apache.org/jira/browse/HBASE-30161
> Project: HBase
> Issue Type: Improvement
> Reporter: Sanjeet Malhotra
> Assignee: Sanjeet Malhotra
> Priority: Major
> Labels: pull-request-available
> Fix For: 4.0.0-alpha-1, 2.7.0, 3.0.0-beta-2, 2.6.6
>
>
> `RegionLocator.getAllRegionLocations()` is currently the only bulk API
>
> to fetch all region locations of a table. Internally it opens a
> `ResultScanner` against `hbase:meta` via
>
> `MetaTableAccessor.scanMetaForTableRegions(...)` and drives
>
> `scanner.next()` in a loop — so the number of RPCs is
>
> `ceil(numRegions / hbase.meta.scanner.caching)`.
>
>
>
> This is a problem for clients (e.g. Phoenix) that want to perform a
>
> *bulk warmup* of their region-location cache after a fresh JVM start
>
> while serializing meta access. The natural pattern is to wrap the call
>
> in a lock — mirroring what `ConnectionImplementation.locateRegionInMeta`
>
> already does for single-region lookups via `userRegionLock`. But
>
> because `getAllRegionLocations()` does N RPCs under one logical call:
>
>
>
> * The lock-timeout budget has to grow with table size — there is no
>
> sensible fixed value that works for both 10-region and 10000-region
>
> tables.
>
> * A single slow RPC inside the loop blocks all other meta lookups for
> the duration.
>
> * Per-call duration is no longer constant w.r.t. data volume.
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