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https://issues.apache.org/jira/browse/HDFS-1320?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12892951#action_12892951
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Erik Steffl commented on HDFS-1320:
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Re fast-path optimization: we don't know and JVM optimizations depends on user
setup (user determines which java command line options are used). Optimizations
also vary across platforms and versions.
Just to make sure I did try code like the following:
LOG.debug("debug log" + a.logSomething());
a.logSomething() is always called, even though debug is not enabled (and debug
log message does not get into log).
It's possible that in different runtime it's optimized away somehow but I don't
think we can rely on it.
Do you have any specific thoughts on how it would be optimized away?
> 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
> Fix For: 0.22.0
>
> Attachments: 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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