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From "Ryan Rawson" <ryano...@gmail.com>
Subject Re: Review Request: HBASE-2468: Improvements to prewarm META cache on clients.
Date Fri, 28 May 2010 21:59:36 GMT


> On 2010-05-28 14:13:14, Benoit Sigoure wrote:
> > src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java, line 306
> > <http://review.hbase.org/r/98/diff/3/?file=741#file741line306>
> >
> >     Please use a concurrent collection and remove the synchronized blocks.  For
guidance, see around slide 30 of this presentation:
> >     http://www.cs.umd.edu/class/fall2009/cmsc132H/slides/still-effective.pdf

Belay that order, I need to inspect this code review... unfortunately a concurrent collection
is not the answer to all multi threading woes.


> On 2010-05-28 14:13:14, Benoit Sigoure wrote:
> > src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java, line 1594
> > <http://review.hbase.org/r/98/diff/3/?file=741#file741line1594>
> >
> >     Use `Boolean.TRUE' instead of `new Boolean(true)'.

Please use the autoboxing features of java6 (our target platform). Ie: just 'true' and 'false'
for this and all others.


- Ryan


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
http://review.hbase.org/r/98/#review93
-----------------------------------------------------------


On 2010-05-28 13:20:33, Mingjie Lai wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://review.hbase.org/r/98/
> -----------------------------------------------------------
> 
> (Updated 2010-05-28 13:20:33)
> 
> 
> Review request for hbase.
> 
> 
> Summary
> -------
> 
> HBASE-2468: Improvements to prewarm META cache on clients.
> 
> Changes:
> 1. Add new HTable methods which support region info de/serialation, and region cache
prewarm: 
> - void serializeRegionInfo(): clients could perform a large scan for all the meta for
the table, serialize the meta to a file. MR job can ship a copy of the meta for the table
in the DistributedCache
> - Map<HRegionInfo, HServerAddress> deserializeRegionInfo(): MR job can deserialize
the region info from the DistributedCache 
> - prewarmRegionCache(Map<HRegionInfo, HServerAddress> regionMap): MR job can prewarm
local region cache by the deserialized region info.
> 
> 2. For each client, each region cache read-miss could trigger read-ahead some number
of rows in META. This option could be turned on and off for one particular table. 
> 
> 
> This addresses bug HBASE-2468.
>     http://issues.apache.org/jira/browse/HBASE-2468
> 
> 
> Diffs
> -----
> 
>   src/main/java/org/apache/hadoop/hbase/client/HConnection.java 853164d 
>   src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java 09de2ac 
>   src/main/java/org/apache/hadoop/hbase/client/HTable.java 7ec95cb 
>   src/main/java/org/apache/hadoop/hbase/client/MetaScanner.java 3de661e 
>   src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java 95e494a 
> 
> Diff: http://review.hbase.org/r/98/diff
> 
> 
> Testing
> -------
> 
> Unit tests passed locally for me. 
> 
> 
> Thanks,
> 
> Mingjie
> 
>


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