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https://issues.apache.org/jira/browse/HBASE-5332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13210721#comment-13210721
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Phabricator commented on HBASE-5332:
------------------------------------
Kannan has commented on the revision "[jira] [HBASE-5332] Deterministic
Compaction Jitter".
Nicolas -- excellent! Minor comments...
INLINE COMMENTS
src/main/java/org/apache/hadoop/hbase/regionserver/Store.java:1068
storeNameStr appears to be the CF name only. Did you intend to take the
regionName also into the seed computation?
Not a big deal.. the fact that you are taking the path name of the first file
should itself be good enough since that's randomized enough. We may not even
need the storeNameStr.
src/main/java/org/apache/hadoop/hbase/regionserver/Store.java:1067 maybe
safer to:
if (storefiles != null && !storefiles.isEmpty()) {
..
}
Maybe the constructor always guarantees that this is initialized to a
0-element list. But nevertheless...
src/main/java/org/apache/hadoop/hbase/regionserver/Store.java:1065 I think
this lock here is unnecessary.
storeFiles points to a immutable list, something that's update wholesale
rather than in-parts at the end of a flush or compaction.
See other uses of this like: getStorefilesIndexSize() which don't take a lock
either.
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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