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https://issues.apache.org/jira/browse/HADOOP-6884?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12903150#action_12903150
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Scott Carey commented on HADOOP-6884:
-------------------------------------
What has been shown is that over 80% of the performance problem, if it exists
(I believe it does, but no one has actually shown that here or in the sibling
tickets), is corrected by removing String concatenation in favor of varargs and
Object[] creation.
So therefore Object[] creation is at least 5x faster than string concatenation.
Generally speaking, autoboxing and transient creation of Object[] would be
similar in cost, so it is probably closer to 10x faster.
Pushing on the SLF4J project (which is actively developed, unlike Log4j and
commons-logging, etc) to add a few method signatures that reduce Object[]
creation and autoboxing feels like a better idea to me than re-inventing SLF4J
-- which was created in the first place to solve this problem along with a few
others.
> Add LOG.isDebugEnabled() guard for each LOG.debug("...")
> --------------------------------------------------------
>
> Key: HADOOP-6884
> URL: https://issues.apache.org/jira/browse/HADOOP-6884
> Project: Hadoop Common
> Issue Type: Improvement
> Affects Versions: 0.22.0
> Reporter: Erik Steffl
> Assignee: Erik Steffl
> Fix For: 0.22.0
>
> Attachments: FunAgain.java, FunAgain.java, HADOOP-6884-0.22-1.patch,
> HADOOP-6884-0.22.patch
>
>
> Each LOG.debug("...") should be executed only if LOG.isDebugEnabled() is
> true, in some cases it's expensive to construct the string that is being
> printed to log. It's much easier to always use LOG.isDebugEnabled() because
> it's easier to check (rather than in each case reason whether it's necessary
> or not).
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