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https://issues.apache.org/jira/browse/HBASE-26726?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrew Kyle Purtell updated HBASE-26726:
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Hadoop Flags: Reviewed
Resolution: Fixed
Status: Resolved (was: Patch Available)
> Allow disable of region warmup before graceful move
> ---------------------------------------------------
>
> Key: HBASE-26726
> URL: https://issues.apache.org/jira/browse/HBASE-26726
> Project: HBase
> Issue Type: Improvement
> Components: master, Region Assignment
> Reporter: Andrew Kyle Purtell
> Assignee: Andrew Kyle Purtell
> Priority: Minor
> Fix For: 2.5.0, 1.7.2, 2.6.0, 3.0.0-alpha-3
>
>
> We have encountered two issues with region warmup before the assignment
> manager gracefully moves a region from one regionserver to another.
> The first instance is HBASE-26722. Part of the failure chain is temporary
> double assignment like conditions where both the source and destination
> regionservers think they have exclusive rights to storefile management (as
> they should) but warmup opens a region before it is closed and then both
> regionservers take compaction related actions. While this can be remediated
> with more care to this case, it is unclear if warmup affords significant
> advantage. The motivation of the original commit in 2015 introducing this
> feature was avoidance of blockcache misses once region ownership transfer was
> advertised to clients. Depending on use case and additional default-false
> schema options (like preload) this could be valuable. Or not.
> The second instance is in place upgrade from HBase 1 to HBase 2. In a
> scenario where regionservers have been replaced by HBase 2 versions, but the
> master is still HBase 1, the region warmup RPC request fails. This is not
> particularly harmful but indicates it will not be useful during the
> transition period.
> We think it would be good to allow for warmup before move to be optionally
> disabled by a site configuration setting. In particular there have been many
> unrelated changes committed since 2015 and expectations of invariants in the
> contribution of the warmup-on-move feature have been invalidated. HBASE-26722
> may be the only case, or it might not. This is a fairly trivial change.
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