[infinispan-dev] trace vs log.isTraceEnabled

[David M. Lloyd]

On 09/28/2011 11:35 AM, Mircea Markus wrote:
> Hi,
>
> I'm not aware of any convention on using trace vs log.isTraceEnabled() to guard the trace statements.
>
> if (trace) log.trace("some request related stuff")
> vs
> if (log.isTraceEnabled()) log.trace("some request related stuff");
>
> The former is more efficient, but cannot be managed at runtime. It seems to be the preferred form, so shall we stick with it?

If you're using the jboss-logging API, and your log statement does not 
do any interpolation, then it is just as fast to do any of the following 
(with no if):

    log.trace("blah");
    log.tracef("the %s happened to %s", foo, bar);
    log.tracev("the {0} happened to {1}", foo, bar);

In the case where trace logging is disabled, these are exactly as 
efficient as the if (log.isTraceEnabled()) variants.  In the case where 
it is enabled, it is marginally more efficient (though the trace log 
itself is substantially more expensive of course).

Overall I'd avoid the "if" forms unless you're doing complex interpolation:

    log.trace("Foo " + bar + " baz " + zap);
    log.tracef("the %s happened to %s", fooMethod().barMethod(), bar);

...both of which incur the expense of the expression resolution even if 
the log message is ultimately discarded.
-- 
- DML