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https://issues.apache.org/jira/browse/HBASE-2663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12893389#action_12893389
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Jonathan Gray commented on HBASE-2663:
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@Ryan, not sure I follow. In what case do you not "defer evictions"? I don't
see how the blocks tenuring would be impacted by the approaches discussed
above. In all cases they would still be in the cache for the same amount of
time and with same numbers of accesses? In the case that we keep things up to
date, we'll access more objects more often so more ref counting. Am I missing
something?
> 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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