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https://issues.apache.org/jira/browse/HBASE-7404?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13803905#comment-13803905
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Jerry He commented on HBASE-7404:
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Any intention and activity putting this in 0.94?
> Bucket Cache:A solution about CMS,Heap Fragment and Big Cache on HBASE
> ----------------------------------------------------------------------
>
> Key: HBASE-7404
> URL: https://issues.apache.org/jira/browse/HBASE-7404
> Project: HBase
> Issue Type: New Feature
> Affects Versions: 0.94.3
> Reporter: chunhui shen
> Assignee: chunhui shen
> Fix For: 0.95.0
>
> Attachments: 7404-0.94-fixed-lines.txt, 7404-trunk-v10.patch,
> 7404-trunk-v11.patch, 7404-trunk-v12.patch, 7404-trunk-v13.patch,
> 7404-trunk-v13.txt, 7404-trunk-v14.patch, BucketCache.pdf,
> hbase-7404-94v2.patch, HBASE-7404-backport-0.94.patch,
> hbase-7404-trunkv2.patch, hbase-7404-trunkv9.patch, Introduction of Bucket
> Cache.pdf
>
>
> First, thanks @neil from Fusion-IO share the source code.
> Usage:
> 1.Use bucket cache as main memory cache, configured as the following:
> –"hbase.bucketcache.ioengine" "heap"
> –"hbase.bucketcache.size" 0.4 (size for bucket cache, 0.4 is a percentage of
> max heap size)
> 2.Use bucket cache as a secondary cache, configured as the following:
> –"hbase.bucketcache.ioengine" "file:/disk1/hbase/cache.data"(The file path
> where to store the block data)
> –"hbase.bucketcache.size" 1024 (size for bucket cache, unit is MB, so 1024
> means 1GB)
> –"hbase.bucketcache.combinedcache.enabled" false (default value being true)
> See more configurations from org.apache.hadoop.hbase.io.hfile.CacheConfig and
> org.apache.hadoop.hbase.io.hfile.bucket.BucketCache
> What's Bucket Cache?
> It could greatly decrease CMS and heap fragment by GC
> It support a large cache space for High Read Performance by using high speed
> disk like Fusion-io
> 1.An implementation of block cache like LruBlockCache
> 2.Self manage blocks' storage position through Bucket Allocator
> 3.The cached blocks could be stored in the memory or file system
> 4.Bucket Cache could be used as a mainly block cache(see CombinedBlockCache),
> combined with LruBlockCache to decrease CMS and fragment by GC.
> 5.BucketCache also could be used as a secondary cache(e.g. using Fusionio to
> store block) to enlarge cache space
> How about SlabCache?
> We have studied and test SlabCache first, but the result is bad, because:
> 1.SlabCache use SingleSizeCache, its use ratio of memory is low because kinds
> of block size, especially using DataBlockEncoding
> 2.SlabCache is uesd in DoubleBlockCache, block is cached both in SlabCache
> and LruBlockCache, put the block to LruBlockCache again if hit in SlabCache ,
> it causes CMS and heap fragment don't get any better
> 3.Direct heap performance is not good as heap, and maybe cause OOM, so we
> recommend using "heap" engine
> See more in the attachment and in the patch
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