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https://issues.apache.org/jira/browse/HBASE-5332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13211641#comment-13211641
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Phabricator commented on HBASE-5332:
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nspiegelberg has commented on the revision "[jira] [HBASE-5332] Deterministic
Compaction Jitter".
INLINE COMMENTS
src/main/java/org/apache/hadoop/hbase/regionserver/Store.java:1067 I can null
check. note that this variable is not null-checked in a lot of places in
Store.java. Wish there was a way to guarantee non-null
src/main/java/org/apache/hadoop/hbase/regionserver/Store.java:1065 I was
worried about a case where this check happened while a major compaction was
finishing up (see Store.completeCompaction). Besides per-file compactions,
the HRegionServer.CompactionChecker thread is another area where this race can
occur.
Maybe this isn't a practical problem since we don't cache this calculation
anymore & the major compaction interval should normally be very large so a race
condition won't trigger a major compaction.
src/main/java/org/apache/hadoop/hbase/regionserver/Store.java:1068 Thinking
about it more, the pathname alone should suffice since it's a 'crypographically
strong' random UUID
REVISION DETAIL
https://reviews.facebook.net/D1785
> Deterministic Compaction Jitter
> -------------------------------
>
> Key: HBASE-5332
> URL: https://issues.apache.org/jira/browse/HBASE-5332
> Project: HBase
> Issue Type: Improvement
> Reporter: Nicolas Spiegelberg
> Assignee: Nicolas Spiegelberg
> Priority: Minor
> Attachments: D1785.1.patch, D1785.2.patch
>
>
> Currently, we add jitter to a compaction using "delay + jitter*(1 -
> 2*Math.random())". Since this is non-deterministic, we can get major
> compaction storms on server restart as half the Stores that were set to
> "delay + jitter" will now be set to "delay - jitter". We need a more
> deterministic way to jitter major compactions so this information can persist
> across server restarts.
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