Java Performance Degradation in JDK7 and JDK8

[Jacob Wieland]

Hello Folks,


I still have the open problem
https://bugs.openjdk.java.net/browse/JDK-8039262 that the javac performance
has degraded significantly from 1.6 to 1.7 (and even worse to 1.8) in the
64bit versions. Since in our context, we are dealing with a lot of
generated source1.4 Java input (either split into very large files with
inner classes or big packages with lots of smaller classes), compiler
performance is critical for our tool and this degradation forces us to
continue recommending to our customers to use Java 1.6 for large projects
(as is the norm) as 1.7 and 1.8 are pretty much unusable in this respect.

Is anyone still working on this issue or is such significant performance
degradation not a serious issue?

My observations so far are:
- it gets worse the more class files are being compiled/the more files
reside in the source path
- cpu usage goes through the roof over all available kernels
- memory usage is much higher
- garbage collection seems to be much more active

Using -proc:none alleviates the problem slightly for the 1.7 version, but
not for 1.8 (last we tested with jdk1.8.0_31) where the performance
difference is a factor 5 or more!

I can understand that a more advanced compiler has capabilities that a
previous version does not have and thus sometimes has
to do more work. But, it should still be possible (especially if given the
-source 1.4 or -source 1.5 option as we do) to optimize it in such a way
that unnecessary checks for generics, overriding methods, closures,
annotations and other newer features can be turned off (if they are to
blame, which I actually doubt from my observations).

I would really appreciate your help in this regard and I think everyone
would benefit from any bugfix you can offer for this.

BR, Jacob Wieland

-- 
-- 
------------------------------
-------------------------------------------
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 testingtech.com
<stanca at testingtech.com>
Fax         +49 30 726 19 19 20        Internet  www.testingtech.com
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