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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-9857) Blockcache prefetch option
Date Sun, 25 May 2014 21:23:02 GMT

    [ https://issues.apache.org/jira/browse/HBASE-9857?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14008442#comment-14008442

Hudson commented on HBASE-9857:

SUCCESS: Integrated in HBase-0.98 #314 (See [https://builds.apache.org/job/HBase-0.98/314/])
Amend HBASE-9857 Blockcache prefetch option; add missing license header to correct file this
time (apurtell: rev a260c862a71c6433213e6619c4de004250468c83)
* hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/PrefetchExecutor.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/AbstractHFileReader.java

> Blockcache prefetch option
> --------------------------
>                 Key: HBASE-9857
>                 URL: https://issues.apache.org/jira/browse/HBASE-9857
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Andrew Purtell
>            Assignee: Andrew Purtell
>            Priority: Minor
>             Fix For: 0.99.0, 0.98.3
>         Attachments: 9857.patch, 9857.patch, HBASE-9857-0.98.patch, HBASE-9857-trunk.patch,
> Attached patch implements a prefetching function for HFile (v3) blocks, if indicated
by a column family or regionserver property. The purpose of this change is to as rapidly after
region open as reasonable warm the blockcache with all the data and index blocks of (presumably
also in-memory) table data, without counting those block loads as cache misses. Great for
fast reads and keeping the cache hit ratio high. Can tune the IO impact versus time until
all data blocks are in cache. Works a bit like CompactSplitThread. Makes some effort not to
> I have been using this for setting up various experiments and thought I'd polish it up
a bit and throw it out there. If the data to be preloaded will not fit in blockcache, or if
as a percentage of blockcache it is large, this is not a good idea, will just blow out the
cache and trigger a lot of useless GC activity. Might be useful as an expert tuning option
though. Or not.

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