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From: Jim Gibson <jimsgibson@gmail.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: analysis of java application logs
Date: Tue, 24 May 2011 11:00:09 -0700
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In article <irgm61$944$1@news.albasani.net>, Lew <noone@lewscanon.com>
wrote:

> Martin Gregorie wrote:
> > Lew wrote:
> >> Martin Gregorie wrote:
> >>> Fair point. However, my usual debugging statement takes the form:
> >>>
> >>> if (debug>   0)
> >>>     debugger.trace(result + " = method(" + arg + ")");
> >>>
> >>> Ugly, I know, but quite efficient, since when debugging is off even the
> >>> cost of the method call cost is. I use an integer to control debugging
> >>> rather than a boolean so I can control its volume: "java Application
> >>> -dd" would be expected to provide more detailed debugging output than
> >>> "java Application -d"
> 
> >> What's wrong with
> >>
> >>     if ( logger.isDebugEnabled() ) ...
> >>
> >> or
> >>
> >>     if ( logger.getLevel().isGreaterOrEqual( Logger.DEBUG )) ...
> >> ?
> 
> > Not a lot, though that does involve method call overheads that you may
> > not want in a tight loop.
> 
> Seems like it's a simple equality test that would be HotSpotted away.

My understanding of the log4j and java.util.Logger classes is that each
logger exists within a hierarchy of classes, and that to determine
whether or not a specific logger call will produce output, the library
must test each level, starting at the specific class and traversing
upwards in the hierarchy. 

So using a static variable as below to enable and disable logging
output can save some execution time:

static final boolean debug = false;

if( debug ) {
  logger.debug(...);
}

Whether or not that is significant, depends upon the situation, of
course.

-- 
Jim Gibson