[slf4j-user] Formatted logs and benchmarks

[Sebastien Pennec]

Hello Martin,

As a follow-up to our performance discussion, here are a few new figures that put the 
differences between MessageFormatter and String.format() in perspective with a 
typical log to a file.

We are logging to a file on the local host, with a simple PatternLayout.

With 1 parameter:
MessageFormatter 11 microseconds
String.format 24 microseconds

With 3 parameters:
MessageFormatter 13 microseconds
String.format 30 microseconds

With 0 parameters:
MessageFormatter 9 microseconds
String.format 11 microseconds

I've simply replaced the code inside MessageFormatter's arrayFormat method with a 
call to String.format(), so that there is no difference in the calls sequence.

We can see that the difference stays important. Seeing these values, I think that we 
should not use the String.format method instead of the MessageFormatter class. This 
question was raised in the previous discussions about this subject, and these tests 
give a clear view of the best choice, I think.

In one of your previous messages, you mentionned the StopWatch that you used to 
measure the values. Based on this class' javadoc[1], it calls the 
System.currentTimeMillis() method to measure time. The System.nanoTime() method is 
much more precise and constant than System.currentTimeMillis(). You might expect more 
constant result using it rather than the StopWatch, unless you're under jdk 1.4, 
where the System.nanoTime() method does not exist.

Cheers,

Sébastien

[1]http://www.springframework.org/docs/api/org/springframework/util/StopWatch.html

Sebastien Pennec wrote:
 > Martin,
 >
 > Sorry for the misreading of your code.
 >
 > Measuring a complete log is actually a good idea. I was pointing this because you
 > mentioned that you had trouble obtaining consistent results, which I had not using
 > my code. This and the first "dry" run were the two main differences between your code
 > and mine.
 >
 > Cheers,
 >
 > Sébastien
 >

-- 
Sébastien Pennec
sebastien at qos.ch

Logback: The reliable, generic, fast and flexible logging framework for Java.
http://logback.qos.ch/