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https://issues.apache.org/jira/browse/HBASE-17819?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16411553#comment-16411553
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stack commented on HBASE-17819:
-------------------------------
+1 for branch-2.0 + branch-2. Thanks [~anoop.hbase]
> Reduce the heap overhead for BucketCache
> ----------------------------------------
>
> Key: HBASE-17819
> URL: https://issues.apache.org/jira/browse/HBASE-17819
> Project: HBase
> Issue Type: Sub-task
> Components: BucketCache
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Priority: Critical
> Fix For: 2.0.0
>
> Attachments: HBASE-17819_V1.patch, HBASE-17819_V2.patch,
> HBASE-17819_V3.patch, HBASE-17819_new_V1.patch, HBASE-17819_new_V1.patch
>
>
> We keep Bucket entry map in BucketCache. Below is the math for heapSize for
> the key , value into this map.
> BlockCacheKey
> ---------------
> String hfileName - Ref - 4
> long offset - 8
> BlockType blockType - Ref - 4
> boolean isPrimaryReplicaBlock - 1
> Total = align(12 (Object) + 17 )= 32
> BucketEntry
> ------------
> int offsetBase - 4
> int length - 4
> byte offset1 - 1
> byte deserialiserIndex - 1
> long accessCounter - 8
> BlockPriority priority - Ref - 4
> volatile boolean markedForEvict - 1
> AtomicInteger refCount - 16 + 4
> long cachedTime - 8
> Total = align(12 (Object) + 51) = 64
> ConcurrentHashMap Map.Entry - 40
> blocksByHFile ConcurrentSkipListSet Entry - 40
> Total = 32 + 64 + 80 = 176
> For 10 million blocks we will end up having 1.6GB of heap size.
> This jira aims to reduce this as much as possible
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