RFR: JDK-8166948: Exploded image too slow to be usable

Erik Joelsson erik.joelsson at oracle.com
Fri Sep 30 14:06:43 UTC 2016


I missed adding a dependency for the cross compilation case. The change 
is in Main.gmk, adding the line:

+      buildtools-modules: create-buildjdk

New webrev: http://cr.openjdk.java.net/~erikj/8166948/webrev.02/


On 2016-09-30 10:03, Erik Joelsson wrote:
> During the build process, we create an exploded image as an interim 
> step before linking the real JDK and JRE images. This exploded image 
> is used both for running certain build tools during the build but is 
> also used by developers when needing a quick build-test cycle since 
> the exploded image is much faster to build incrementally.
> Lately, with newer Jigsaw features, the exploded image has become very 
> slow to run. This is caused by the runtime needing to index all 
> packages in all modules at startup. In a linked image, this data is 
> pregenerated, but in the exploded case, it's not. There have been 
> reports of this taking up to 4-5 seconds on certain configurations.
> To fix this, we can add a new build tool that is run on the exploded 
> image, which updates the module-info.class files with this package 
> index. This will also have the benefit of also speeding up jmod and 
> jlink when run during the build.
> Alan provided the tool and I have modified the build to use it.
> Bug: https://bugs.openjdk.java.net/browse/JDK-8166948
> Webrev: http://cr.openjdk.java.net/~erikj/8166948/webrev.01/
> /Erik

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