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https://issues.apache.org/jira/browse/HBASE-10403?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13881251#comment-13881251
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Nick Dimiduk commented on HBASE-10403:
--------------------------------------
Thanks for the comments [~zjushch]! I'll include them in the next patch. This
was just a WIP I wanted to share to see if you liked the direct. So you like
disentangling BlockCache instantiation into the static factory methods? Any
complaint about the reflection business? Is there need for a more "concrete"
factory type class, etc?
Especially now in light of HBASE-6048 resurfacing, I think it's a good idea to
decouple the multilevel cache strategies from the implementations they wrap.
This will be more invasive, but it would allow a user to use CombinedBlockCache
with SlabCache via configuration.
What do you think about the idea of "named" configurations? IE, including some
preset configuration by the name "BucketCache offheap". Is that too much?
> Simplify offheap cache configuration
> ------------------------------------
>
> Key: HBASE-10403
> URL: https://issues.apache.org/jira/browse/HBASE-10403
> Project: HBase
> Issue Type: Bug
> Components: io
> Reporter: Nick Dimiduk
> Assignee: Nick Dimiduk
> Priority: Minor
> Attachments: HBASE-10403.0.patch
>
>
> The BucketCache (HBASE-7404) is a very nice piece of functionality which is
> hidden behind complex configuration. Enabling it currently requires manual
> calculation of L1 cache. It'd be nice to make this easier to use and conform
> better with the existing heap management tools we already have.
> Turning it on currently requires explicitly setting LruBlockCache (L1)
> instance size and IOEngine (L2) size, making sure that L1 size isn't too big
> vs global memstore and total heap. This is further confused by
> hbase.bucketcache.size accepting a percentage of total heap OR explicit size
> in MB. Enabling SlabCache is slightly easier in that it just accepts whatever
> LruBlockCache is provided.
> Turning on BucketCache using off-heap mode could look like:
> hbase-env.sh:
> Set HBASE_REGIONSERVER_OPTS:
> -Xmx5000m
> -XX:MaxDirectMemorySize=15000m
> hbase-site.xml:
> - hbase.regionserver.global.memstore.size = 0.7
> - hbase.regionserver.onheap.blockcache.size = 0.1
> - hbase.regionserver.blockcache.impl = BucketCache
> - hbase.bucketcache.ioengine = offheap
> The result being a CombinedCache instance with 500m LruBlockCache + 15000m
> ByteBufferIOEngine running in direct mode.
> This example does a couple things (mostly for the admin):
> - knows NOT to enable SlabCache
> - s/hfile.block.cache.size/hbase.regionserver.onheap.blockcache.size/
> - maintains the validity of HBaseConfiguration's existing check that global
> MemStore + LruBlockCache == 0.8
> - maps "BucketCache" into meaning "a CombinedCache instance with these
> implementations for L1 and L2."
> - Figures out appropriate values for hbase.bucketcache.size and
> hbase.bucketcache.percentage.in.combinedcache
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