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https://issues.apache.org/jira/browse/HBASE-2468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12873150#action_12873150
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HBase Review Board commented on HBASE-2468:
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Message from: "Benoit Sigoure" <tsuna...@gmail.com>
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src/main/java/org/apache/hadoop/hbase/client/HConnection.java
<http://review.hbase.org/r/98/#comment531>
Properly document this argument.
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment534>
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
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment532>
Coding style: put the catch on the previous line.
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment533>
We don't typically call methods using `this.methodname(args)' – remove the
`this.'
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment535>
Add a space before the `:'.
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment536>
Use `Boolean.TRUE' instead of `new Boolean(true)'.
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment537>
Use `Boolean.FALSE' instead of `new Boolean(false)'.
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment538>
Use `Boolean.TRUE' instead of `new Boolean(true)'.
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment539>
Remove the outer parentheses.
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment540>
Add a space before the `:'.
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment541>
If this fits on the previous line while staying under 80 columns, please
wrap it around.
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment542>
Remove the space after `cacheLocation'
src/main/java/org/apache/hadoop/hbase/client/HTable.java
<http://review.hbase.org/r/98/#comment546>
Use {...@link #readFields readFields} instead of <code>readFields</code>
src/main/java/org/apache/hadoop/hbase/client/HTable.java
<http://review.hbase.org/r/98/#comment544>
You can remove this <p>
src/main/java/org/apache/hadoop/hbase/client/HTable.java
<http://review.hbase.org/r/98/#comment543>
Use <pre> not <code>
src/main/java/org/apache/hadoop/hbase/client/HTable.java
<http://review.hbase.org/r/98/#comment545>
Add a space before the `:'.
src/main/java/org/apache/hadoop/hbase/client/HTable.java
<http://review.hbase.org/r/98/#comment547>
Use {...@link #getRegionsInfo getRegionsInfo}
src/main/java/org/apache/hadoop/hbase/client/HTable.java
<http://review.hbase.org/r/98/#comment548>
Use {...@link ...} here and below.
src/main/java/org/apache/hadoop/hbase/client/HTable.java
<http://review.hbase.org/r/98/#comment550>
Wrap this around with the previous line.
src/main/java/org/apache/hadoop/hbase/client/HTable.java
<http://review.hbase.org/r/98/#comment549>
I believe you can remove this block.
- Benoit
> Improvements to prewarm META cache on clients
> ---------------------------------------------
>
> Key: HBASE-2468
> URL: https://issues.apache.org/jira/browse/HBASE-2468
> Project: HBase
> Issue Type: Improvement
> Components: client
> Reporter: Todd Lipcon
> Assignee: Mingjie Lai
> Fix For: 0.21.0
>
> Attachments: HBASE-2468-trunk.patch
>
>
> A couple different use cases cause storms of reads to META during startup.
> For example, a large MR job will cause each map task to hit meta since it
> starts with an empty cache.
> A couple possible improvements have been proposed:
> - MR jobs could ship a copy of META for the table in the DistributedCache
> - Clients could prewarm cache by doing a large scan of all the meta for the
> table instead of random reads for each miss
> - Each miss could fetch ahead some number of rows in META
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