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https://issues.apache.org/jira/browse/HBASE-24428?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Guanghao Zhang updated HBASE-24428:
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Fix Version/s: (was: 2.2.5)
2.2.6
> Priority compaction for recently split daughter regions
> -------------------------------------------------------
>
> Key: HBASE-24428
> URL: https://issues.apache.org/jira/browse/HBASE-24428
> Project: HBase
> Issue Type: Improvement
> Components: Compaction
> Reporter: Andrew Kyle Purtell
> Assignee: Viraj Jasani
> Priority: Major
> Fix For: 3.0.0-alpha-1, 2.3.0, 1.7.0, 2.2.6
>
>
> We observe that under hotspotting conditions that splitting will proceed very
> slowly and the "_Cannot split region due to reference files being there_" log
> line will be logged excessively. (branch-1 based production.) This is because
> after a region is split it must be compacted before it can be split again.
> Reference files must be replaced by real HFiles, normal housekeeping
> performed during compaction. However if the regionserver is under excessive
> load, its compaction queues may become deep. The daughters of a recently
> split hotspotting region may themselves continue to hotspot and will rapidly
> need to split again. If the scheduled compaction work to remove/replace
> reference files is queued hundreds or thousands of compaction queue elements
> behind current, the recently split daughter regions will not be able to split
> again for a long time and may grow very large, producing additional
> complications (very large regions, very deep replication queues).
> To help avoid this condition we should prioritize the compaction of recently
> split daughter regions. Compaction requests include a {{priority}} field and
> CompactionRequest implements a comparator that sorts by this field. We
> already detect when a compaction request involves a region that has reference
> files, to ensure that it gets selected to be eligible for compaction, but we
> do not seem to prioritize the requests for post-split housekeeping. Split
> work should be placed at the top of the queue. Ensure that this is happening.
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