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https://issues.apache.org/jira/browse/HBASE-2663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12891314#action_12891314
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stack commented on HBASE-2663:
------------------------------

What you thinking?  A PriorityDequeue?  An implementation is not easy to come 
by.  It'd be less performant keeping sort up on both ends.  I wonder if we just 
used a NavigableSet, if that'd be performant enough.  We'd have to change the 
compare to take into consideration priority.

> LRU cache makes needless datastructure copies during eviction
> -------------------------------------------------------------
>
>                 Key: HBASE-2663
>                 URL: https://issues.apache.org/jira/browse/HBASE-2663
>             Project: HBase
>          Issue Type: Improvement
>          Components: regionserver
>            Reporter: Todd Lipcon
>
> Was browsing the LRU eviction code and came upon some very inefficient code. 
> When we do eviction, BlockBucket.free() calls queue.get() which first inserts 
> everything from the PriorityQueue<Block> into a LinkedList, then copies that 
> entire linked list into an array. We then iterate over usually just a small 
> percentage of the array to free some blocks until we have freed the requested 
> amount.
> We ought to be able to just pull items out of the PriorityQueue directly and 
> avoid all the churn.

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