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https://issues.apache.org/jira/browse/HBASE-15366?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15175042#comment-15175042
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ramkrishna.s.vasudevan commented on HBASE-15366:
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bq.BUCKET_CACHE_PERSISTENT_PATH_KEY
The doc on this is great. I have not used this param.
bq.Fix it so we do NOT put the NextHeader into blockcache. It is not necessary.
So the bucket cache is also caching these extra bytest you mean? This is
interesting. Worth changing it I believe.
bq.Set BAOS initial size. Use fileContext.getBlocksize() and add for
header/checksum
True. Already this area is a big garbage creator in a default case.
bq.// TODO : change this area - should be removed after server cells and
Sorry my fault. This has to be removed now. Already this is done I believe.
> Add doc, trace-level logging, and test around hfileblock
> --------------------------------------------------------
>
> Key: HBASE-15366
> URL: https://issues.apache.org/jira/browse/HBASE-15366
> Project: HBase
> Issue Type: Sub-task
> Components: BlockCache
> Affects Versions: 2.0.0
> Reporter: stack
> Assignee: stack
> Fix For: 2.0.0
>
> Attachments: 15366.patch, 15366v2.patch, 15366v3.patch, 15366v4.patch
>
>
> What hfileblock is doing -- that it overreads when pulling in from hdfs to
> fetch the header of the next block to save on seeks; that it caches the block
> and overread and then adds an extra 13 bytes to the cached entry; that
> buckets in bucketcache have at least four hfileblocks in them and so on --
> was totally baffling me. This patch docs the class, adds some trace-level
> logging so you can see if you are doing the right thing, and then adds a test
> of file-backed bucketcache that checks that persistence is working.
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