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From "Tsz Wo (Nicholas), SZE (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-6884) Add LOG.isDebugEnabled() guard for each LOG.debug("...")
Date Thu, 19 Aug 2010 17:57:18 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-6884?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12900377#action_12900377
] 

Tsz Wo (Nicholas), SZE commented on HADOOP-6884:
------------------------------------------------

> What does this show? ...

Your benchmark also shows that LOG.isDebugEnabled() provides the best results.  A patch using
this approach is already there.  Do you really want to stop committing it?

There may be other comparable solutions out there but (1) we don't have a patch yet, (2) it
may require further modifying the codes and (3) the performance is not as good as LOG.isDebugEnabled().

I forgot to mention that my benchmark only measures running time but it does not account the
GC overhead induced by unnecessary object creation due to auto-boxing.  This is another reason
that LOG.isDebugEnabled() is better than the other suggested solution.

> 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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