Javac performance degradation of JDK 7 vs. 6

[Jan Lahoda]

Hello Jacob,

I am looking at the issue a little bit. This will probably need a deeper 
investigation, but there indeed seems to be a considerable difference in 
compilation times of the testcase between JDK 6 64bit and JDK 7 64 bit 
when the annotation processing is enabled, even if given enough heap 
size. I am not yet clear on what is the cause.

Thanks,
     Jan

On 14.7.2014 22:10, Jacob Wieland wrote:
> Hello folks,
>
> Some time ago, I have raised the issue
> https://bugs.openjdk.java.net/browse/JDK-8039262 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,
>
> Jacob
>
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