Java Performance Degradation in JDK7 and JDK8

Wed Apr 29 11:15:05 UTC 2015

Hello Maurizio,

I was wondering the same thing. However, I have changed the code-pattern
experimentally to use no inner classes (at least not as many) and instead
use top-level-classes which all reference each other (and need explicit
references where before there were convenient implicit references to the
containing outer class objects) and the performance got worse instead of
better, so I don't know if it has to do with inner classes after all. Of
course, it could be inner classes in one case and lots of files in the
other. But that's just guesswork.

Is there a fix for the above issue that could be tried out. We are
definitely not using class names like A$B in our context.

2015-04-29 11:29 GMT+02:00 Maurizio Cimadamore <
maurizio.cimadamore at oracle.com>:

>  Hi Jacob,
> Stay assured - as we'll definitively look into this issue (I see it's
> already assigned to one of my colleagues).
>
> What I can say (w/o looking too much at the attached artifacts) is that in
> general, javac has no issue with compiling a lot of sources at once; at one
> point the build system was structured in such a way that all the JDK
> classes were compiled at once - and that (which is way more than your 187
> sources - i.e. at least 10x that) took less than 20 seconds. SO there must
> some specific pattern triggering that issue.
>
> Given that you say you have 187 input sources and 48K output classes, I'd
> say you are using inner classes a lot. I wonder if you are hitting this:
>
> https://bugs.openjdk.java.net/browse/JDK-8000316
>
> Maurizio
>
>
> On 24/04/15 09:49, Jacob Wieland wrote:
>
> 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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-- 
-- 
------------------------------
-------------------------------------------
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
---------------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------------------------

UPCOMING EVENTS

SUBMIT YOUR TOPIC for the UCAAT 2015
Deadline: May 30, 2015ucaat.etsi.org/2015/CallForPresentations.html

Apr 21-23, 2015 | SAE Conference & Exhibition
Detroit, Michigan, USAwww.sae.org/congress/

Apr 28-30, 2015 | iqnite
Dusseldorf, Germanywww.iqnite-conferences.com/de/index.aspx

-----------------------------------------------------------------------------------------------------------------
Geschäftsführung: Theofanis Vassiliou-Gioles, Stephan Pietsch, Pete
Nicholson Handelsregister HRB 77805 B, Amtsgericht Charlottenburg Ust ID
Nr.: DE 813 143 070 This email may contain confidential and privileged
material for the sole use of the intended recipient. Any review, use,
distribution or disclosure by others is strictly prohibited. If you are not
the intended recipient (or authorized to receive for the recipient), please
contact the sender by reply email and delete all copies of this message.
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