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https://issues.apache.org/jira/browse/HBASE-8299?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13627177#comment-13627177
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Sergey Shelukhin commented on HBASE-8299:
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I get that it needs to be fixed, but this fix affects the cases beyond the ones
it's looking to solve, so I am looking for another, or modified, fix.
This fix changes the logic of requestCompaction to force compaction every
time it's called when needsCompaction is true, which is different from current
behavior (and that for old default policy) where needsCompaction is an
inaccurate pre-check and real decision is done in requestCompaction, which is
called speculatively form many place. Changing semantics of requestCompaction
like that will cause bad compactions in normal cases where compaction is not
needed.
Including bad consequences with many compactions (see compaction checker - how
it runs compactions).
I am looking to avoid that.
The ways to avoid it that can be used are:
1) Keep this patch but add force flag/method which will trigger this behavior
of "select compaction regardless of ratio".
2) Change semantics of needsCompaction and requestCompaction across the code so
that the assumption this patch makes is actually true.
3) Change the heuristic to not get stuck in such case via other means.
It seems that (1) is the simplest.
> ExploringCompactionPolicy can get stuck in rare cases.
> ------------------------------------------------------
>
> Key: HBASE-8299
> URL: https://issues.apache.org/jira/browse/HBASE-8299
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.95.1
> Reporter: Elliott Clark
> Assignee: Elliott Clark
> Attachments: HBASE-8299-0.patch
>
>
> If the files are very oddly sized then it's possible that
> ExploringCompactionPolicy can get stuck.
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