Javac performance degradation of JDK 7 vs. 6

Jacob Wieland wieland at
Mon Jul 14 20:10:27 UTC 2014

Hello folks,

Some time ago, I have raised the issue and now have been referred
to you
gentle people in the hope that someone might have some ideas and the time
and energy to resolve it.

It is about a serious javac performance degradation in the 64 bit version
of Java 7 (and higher) in comparison to the 64 bit version
of Java 6. If annotation processing is not specifically turned off (which
helps somewhat, even though performance is still 10% or so worse than for
Java 6), the same java code very often takes several minutes instead of 40
to 50 seconds to compile. Also, it uses much more CPU (all 4 cores of my
computer seem to be fully busy) and memory in the process. My guess is that
there is some paralellization optimization going on that in our case is a
pessimization, probably involving garbage collection (as that is where the
compiler seems to be spending its time mainly, regardless how much memory I
throw at it (more memory actually seems to make it worse) if looking at
-verbose:gc is to be believed.

Also, there seems to be a serious problem regarding source-file-lookup in
large packages (containing thousands of source files).

If there are any further questions that are not covered by the bug in the
mentioned link, I'm happy to answer them.

Thanks for your help,


Dr. Jacob Wieland
Senior Software Engineer

Testing Technologies IST GmbH
Michaelkirchstraße 17/18
10179 Berlin, Germany

Phone     +49 30 726 19 19 34        Email     wieland at
<stanca at>
Fax         +49 30 726 19 19 20        Internet



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