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https://issues.apache.org/jira/browse/HDFS-1320?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12900484#action_12900484
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Tsz Wo (Nicholas), SZE commented on HDFS-1320:
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> does the JVM not optimize for this case in the fast-path?
Hi Ryan, from the benchmark results
[here|https://issues.apache.org/jira/browse/HADOOP-6884?focusedCommentId=12900087&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_12900087],
it does not seem JVM optimized this. I think JVM cannot do anything in
general since parameter evaluation may have side-effect. It is hard for the
JVM to determine whether it is safe to skip those instructions.
> Add LOG.isDebugEnabled() guard for each LOG.debug("...")
> --------------------------------------------------------
>
> Key: HDFS-1320
> URL: https://issues.apache.org/jira/browse/HDFS-1320
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: 0.22.0
> Reporter: Erik Steffl
> Assignee: Erik Steffl
> Fix For: 0.22.0
>
> Attachments: HDFS-1320-0.22-1.patch, HDFS-1320-0.22-2.patch,
> HDFS-1320-0.22.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 wheather it's
> neccessary or not).
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