Yes, Mike is exactly right here.
The only reason to wrap a log.debug() in log4j is when passing the argument(s) is very
expensive and a simple (2) string concatenation doesn't qualify. Even passing an object
with an expensive toString() argument isn't a problem because the log4j lib is optimized
to process the args only when the specified logging level criteria is met.
Mike McCune wrote:
Devan Goodwin wrote:
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Hash: SHA1
On Wed, 18 Mar 2009 11:57:00 -0400
Justin Sherrill <jsher...@redhat.com> wrote:
Might be a nice thing to do after the next fork for Sat. Having to
use log.isDebugEnabled() is ugly IMO and it'd be nice not to have to
do it where we don't have to.
I hate doing this too. I was gonna take issue with it as it's ugly and
seemed pretty silly until I googled and saw that it is best practice if
the statement is doing string contact.
This the rule I followed as well. Wrap the log.debug() in the if
statement only if it was doing string concatenation of variables in your
method.
I'd rather have lots of nice debug statements and a performance hit than
people skipping adding logging to our classes because it looks ugly.
I'd propose you only wrap if you are doing a:
log.debug("something to debug: " + somevariable);
otherwise wrapping this:
if (log.isDebugEnabled()) {
log.debug("Some message");
}
is largely pointless.
StopWatch st = new StopWatch();
st.start();
for (int i = 0; i < 100000000; i++) {
log.debug("Some line of debug");
}
st.stop();
System.out.println("Time: " + st.getTime());
output is ~500ms for a hundred million executions. And this:
StopWatch st = new StopWatch();
st.start();
for (int i = 0; i < 100000000; i++) {
if (log.isDebugEnabled()) {
log.debug("Some line of debug");
}
}
st.stop();
System.out.println("Time: " + st);
is actually 600ms! The if statement actually costs more than the simple
call to log.debug()
Concatenation does cost ya ...
StopWatch st = new StopWatch();
String rand = TestUtils.randomString();
st.start();
for (int i = 0; i < 100000000; i++) {
log.debug("Some line of debug" + rand);
}
st.stop();
is actually around 12 seconds. Not horrible but could be bad if the
strings are large.
Mike
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