Emmanuel Lecharny schrieb:
Hi,
in this very case, the DN won't be parsed, as the getUpName() just
returns the inner String.
The difference between a direct call to log.debug and the if
(IS_DEBUG) is that if the IS_DEBUG is set to false, then the compiler
will simply not do the test at all, because it's a static variable,
and it will be optimized internally by a removal of this portion of
the code.
So the "is (IF_DEBUG)" will be faster than a call to the LOG.debug()
method, sparing the call.
Keep in mind that it's marginal, but in some places where we have a
lot of LOGs, this is interesting to use this trick.
Also this is valid for DEBUG mode, not for info, as it won't be
anymore possible to activate the log dynamically without restarting
the server, as the bytecode will not contain the call anymore.
I'm not totally up to date about which logger is used, but for log4j
i.e. exists also a method LOG.isDebugEnabled() to test this (it's
probably a little bit slower as it is not static), but its configurable
and the code should also stay in the bytecode.
What I don't exactly now is if the config can be changed at runtime.
Felix
Ersin Er wrote:
Hi,
I think this is more of an issue of parameter evaluation than string
concatenation. If you do not do a IS_DEBUG check first, then even if the
debug is not enabled, opContext.getEntry() and
opContext.getDn().getUpName()
will have to be evaluated first (before the debug method is called).
So if
these are particularly expensive operations you may have a serious
CPU cycle
loss. The example here is not perfect for demostrating this situation
but if
one of the parameters was calculated via a DN parsing operation then the
result (without IS_DEBUG) would be quite bad.
Greetings,
On Fri, Jun 6, 2008 at 7:40 AM, Alex Karasulu <[EMAIL PROTECTED]>
wrote:
Emmanuel,
I see in some places you protect calls to LOG.debug() for example
with a
IS_DEBUG conditional like so:
if ( IS_DEBUG )
{
LOG.debug( "Adding the entry {} for DN = '{}'",
opContext.getEntry(), opContext.getDn().getUpName() );
}
If the {} based substitution is used, then does this not protect us
from
additional String concatenation? Is the above more efficient than:
LOG.debug( "Adding the entry {} for DN = '{}'",
opContext.getEntry(), opContext.getDn().getUpName() );
Thanks,
Alex
