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https://issues.apache.org/jira/browse/HBASE-4752?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13145693#comment-13145693
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Jonathan Gray commented on HBASE-4752:
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Sorry I didn't chime in earlier, been traveling.
I'm actually -1 on this change at the moment because of the introduction of a
Google class (now the block cache has this external dependency). This class is
actually used by other projects outside of HBase, so I'd hate to put in an
unnecessary dependency. Is there additional value we get out of using the
MinMaxPQ? We save a LinkedList allocation?
As for the change in behavior, I'm not sure I follow. Seems like nothing
actually changes? (whether the PQ is cleared or not doesn't really matter,
behavior-wise?)
The way I'm reading the code, it seems like we could actually just remove the
LL completely and leave in place the regular PQ? CachedBlock takes care of the
sort order, no?
> Don't create an unnecessary LinkedList when evicting from the BlockCache
> ------------------------------------------------------------------------
>
> Key: HBASE-4752
> URL: https://issues.apache.org/jira/browse/HBASE-4752
> Project: HBase
> Issue Type: Improvement
> Components: performance, regionserver
> Affects Versions: 0.90.4
> Reporter: Benoit Sigoure
> Assignee: Ted Yu
> Priority: Minor
> Fix For: 0.94.0
>
> Attachments:
> 0001-HBASE-4752-Don-t-create-an-unnecessary-LinkedList-wh.patch,
> 4752-trunk-v2.txt, 4752-trunk.txt
>
>
> When evicting from the BlockCache, the code creates a LinkedList containing
> every single block sorted by access time. This list is created from a
> PriorityQueue. I don't believe it is necessary, as the PriorityQueue can be
> used directly.
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