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https://issues.apache.org/jira/browse/LOG4J2-547?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13944679#comment-13944679
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Remko Popma commented on LOG4J2-547:
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Micro-benchmarks can be tricky stuff. Do you get the same results if you first
measure bottom-up, then top-down? Or start with recurse(500), and work down to
recurse(100)?
Things that make it tricky:
* avoid measuring during the first 3-10 seconds after the JVM started, as JVM
initialization is still taking place in parallel
* Hotspot will compile "hot" code to native code. The default threshold is
after 10,000 invocations. So in the example this will happen sometime while you
are measuring.
* During compilation, hotspot will look at places to optimize. The loop can be
unrolled, and statements in the loop re-ordered. If hotspot determines the code
has no side-effects (doesn't change any state) and doesn't return a value, it
may decide to optimize by simply not executing that code... Same results, but a
lot faster. :-)
If you have time, please take a look at
[JMH|http://openjdk.java.net/projects/code-tools/jmh/].
JHM is specifically designed to avoid these and other pitfalls.
> Update LoggerStream API
> -----------------------
>
> Key: LOG4J2-547
> URL: https://issues.apache.org/jira/browse/LOG4J2-547
> Project: Log4j 2
> Issue Type: Improvement
> Components: API
> Affects Versions: 2.0-rc1
> Reporter: Matt Sicker
> Assignee: Ralph Goers
> Fix For: 2.0-rc2
>
> Attachments: 0001-PrintStream-API-update.patch,
> PerfTestCalcLocation.java, log4j2-547-bbrouwer.patch,
> log4j2-loggerStream.patch
>
>
> I've got some ideas on how to improve the LoggerStream idea that I added a
> little while ago. The main thing I'd like to do is extract an interface from
> it, rename the default implementation to SimpleLoggerStream (part of the
> SimpleLogger stuff), and allow log4j implementations to specify a different
> implementation if desired.
> In doing this, I'm not sure where specifically I'd prefer the getStream
> methods to be. Right now, it's in Logger, but really, it could be in
> LoggerContext instead. I don't think I should be required to get a Logger
> just to get a LoggerStream.
> Now if only the java.io package used interfaces instead of classes. This
> would be so much easier to design!
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