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https://issues.apache.org/jira/browse/HBASE-8163?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13613507#comment-13613507
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stack commented on HBASE-8163:
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[~zjushch] Are you fellas running this and if so, what is your experience?
The patch looks good to me. In release note you should be clear that it is off
by default and explain how to turn it on (it is not that obvious). I'd be +1
on this coming into trunk and 0.95.
> MemStoreChunkPool: An improvement for JAVA GC when using MSLAB
> --------------------------------------------------------------
>
> Key: HBASE-8163
> URL: https://issues.apache.org/jira/browse/HBASE-8163
> Project: HBase
> Issue Type: New Feature
> Components: regionserver
> Reporter: chunhui shen
> Assignee: chunhui shen
> Attachments: hbase-8163v1.patch, hbase-8163v2.patch,
> hbase-8163v3.patch, hbase-8163v4.patch, hbase-8163v5.patch
>
>
> *Usage:*
> Disable pool(default): configure "hbase.hregion.memstore.chunkpool.maxsize"
> as 0
> Enable pool: configure "hbase.hregion.memstore.chunkpool.maxsize" as a
> percentage of global memstore size (between 0.0 and 1.0, recommend to set it
> as the gap between min and max sizes of memstore, e.g. 0.5f)
> *Background*：
> When we use mslab,we will copy the keyvalue together in a structure called
> *MemStoreLAB$Chunk*, therefore we could decrease the heap fragment.
> *Problem*：
> When one chunk is full, we will create a new chunk, and then the old chunk
> will be reclaimed by JVM if no reference to it.
> Mostly the chunk object would be promoted when doing Young GC, cause
> increasing the cost of YGC
> When a Chunk object has no reference? It should meet two following condition:
> 1.Memstore which this chunk belongs to is flushed
> 2.No scanner is opening on the memstore which this chunk belongs to
> *Solution:*
> 1.Create a chunk pool to manage the no-reference chunks, instead of being
> reclaimed by JVM
> 2.When a Chunk has no reference, put it back to the pool
> 3.The pool has a max capacity, it will skip the chunks when achieve the max
> size
> 4.When we need new Chunk to store KeyValue, get it from the pool if exists,
> else create new one by pool, so we could be able to reuse the old chunks
> *Test results:*
> Environment:
> hbase-version:0.94
> -Xms4G -Xmx4G -Xmn2G
> Row size=50 bytes, Value size=1024 bytes
> 50 concurrent theads per client, insert 10,000,000 rows
> Before:
> Avg write request per second:12953
> After testing, final result of jstat -gcutil :
> YGC YGCT FGC FGCT GCT
> 747 36.503 48 2.492 38.995
> After:
> Avg write request per second:14025
> After testing, final result of jstat -gcutil :
> YGC YGCT FGC FGCT GCT
> 711 20.344 4 0.284 20.628
> *Improvement: YGC 40+%; WPS 5%+*
> review board :
> https://reviews.apache.org/r/10056/
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