[jira] [Updated] (PHOENIX-7799) Coalesce splits by region server to avoid hotspotting from concurrent mappers

["Rahul Kumar (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PHOENIX-7799?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rahul Kumar updated PHOENIX-7799:
---------------------------------
    Affects Version/s: 5.3.0
                       5.2.1
                           (was: 5.1.3)

> Coalesce splits by region server to avoid hotspotting from concurrent mappers
> -----------------------------------------------------------------------------
>
>                 Key: PHOENIX-7799
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-7799
>             Project: Phoenix
>          Issue Type: Sub-task
>    Affects Versions: 5.2.0, 5.2.1, 5.3.0
>            Reporter: Rahul Kumar
>            Assignee: Rahul Kumar
>            Priority: Major
>
> PhoenixSyncTableTool creates one MapReduce InputSplit per HBase region, causing each split to spawn its own mapper task. When multiple regions reside on the same RegionServer, concurrent mappers hit the same server simultaneously, leading to hotspotting and resource contention (noisy neighbor problem). This degrades performance and can cause timeouts.
> Implement locality-aware split coalescing that groups all InputSplits from the same RegionServer into a single coalesced split. This ensures only one mapper processes regions from each server sequentially, eliminating concurrent requests and hotspotting. The feature will be controlled by the configuration property phoenix.sync.table.split.coalescing (default: false). For a table with 100 regions across 5 RegionServers, this reduces mapper count from 100 to 5, eliminating server-side contention while maintaining data locality.



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