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https://issues.apache.org/jira/browse/HBASE-2997?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12909923#action_12909923
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HBase Review Board commented on HBASE-2997:
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Message from: "Ryan Rawson" <[email protected]>
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src/main/java/org/apache/hadoop/hbase/KeyValue.java
<http://review.cloudera.org/r/843/#comment4189>
key values are only used by 1 thread at a time, so no.
and even if they were shared, we'd just result in the current situation -
use more cpu than is theoretically necessary.
src/main/java/org/apache/hadoop/hbase/KeyValue.java
<http://review.cloudera.org/r/843/#comment4190>
it actually is worth it... also key values tend to be short lived, but
recopying this array out half a dozen times during a scan is pricy according to
the profiler. 6% cpu.
src/main/java/org/apache/hadoop/hbase/KeyValue.java
<http://review.cloudera.org/r/843/#comment4191>
in a 64 bit jvm you cannot read a partial long, the updates are atomic.
this is part of the spec. also single threaded comment above.
- Ryan
> Performance fixes - profiler driven
> -----------------------------------
>
> Key: HBASE-2997
> URL: https://issues.apache.org/jira/browse/HBASE-2997
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.89.20100621
> Reporter: ryan rawson
> Assignee: ryan rawson
> Priority: Critical
> Fix For: 0.90.0
>
> Attachments: HBASE-2997-1.txt, HBASE-2997-2.txt, HBASE-2997-3.txt,
> HBASE-2997-4.txt, HBASE-2997-5.txt
>
>
> while profiling hbase I found a number of slow pieces. Here are fixes for
> them.
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