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https://issues.apache.org/jira/browse/HADOOP-6884?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12899145#action_12899145
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Doug Cutting commented on HADOOP-6884:
--------------------------------------
> 1. Code must remain as readable/simple as possible and maintainable (no
> wrapping isDebugEnabled() in all of source code).
Does anyone believe that? I think the guards should ideally be limited to
performance sensitive parts of the code. But if folks don't trust that can be
maintained, then a warning when non-constant strings are logged might be
acceptable. Constant strings should be as fast as the guard.
> 2. Code must perform best (no varargs, autoboxing, string concatenation, etc
> for unused debug lines)
We could easily implement a guard that both performs well and does not bloat
code, e.g.:
{code}
public static void debugLog(String message) { LOG.debug(message); }
public static void debugLog(String message, Object o1) {
if (LOG.isDebugEnabled())
LOG.debug(MessageFormat.format(message, new Object[] {o1}));
}
public static void debugLog(String message, Object o1, Object o2) {
if (LOG.isDebugEnabled())
LOG.debug(MessageFormat.format(message, new Object[] {o1, o2}));
}
public static void debugLog(String message, Object o1, Object o2, Object o3) {
if (LOG.isDebugEnabled())
LOG.debug(MessageFormat.format(message, new Object[] {o1, o2, o3}));
}
...
{code}
> 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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