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https://issues.apache.org/jira/browse/HADOOP-6884?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12898007#action_12898007
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Erik Steffl commented on HADOOP-6884:
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Re
https://issues.apache.org/jira/browse/HADOOP-6884?focusedCommentId=12897536&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_12897536
Me too however then there's no way to automatically or at least
semi-automatically check for the cases where the optimisation would be helpful.
If all debug() logging calls have isDebugEnabled() guard it's easy to check the
whole codebase in few minutes (I have a simple script that only produces few
false positives that need to be eyeballed). If the guard is used in minority of
cases where it's actually useful then verification whether it's used everywhere
where it's needed is very expensive.
Possibly better solutions but I don't think they are realistic in short/medium
term:
- use scala and lazy values (arguments for debug() are not constructed unless
used)
- use extensive profiling and see where debug() calls matter (this could be
part of automatic builds/tests)
> 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: 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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