RFR: 8150044: Generate classlists at build-time

Jim Laskey (Oracle) james.laskey at oracle.com
Wed May 4 14:29:15 UTC 2016

Once installed, autoconf ran properly with make reconfigure - thx.

> On May 4, 2016, at 11:24 AM, Erik Joelsson <erik.joelsson at oracle.com> wrote:
> Depends on which OS you are using. You need version 2.69, which is the latest. On linux, "apt-get/yum install autoconf" should do the trick unless your distribution is ancient. On windows add autoconf through the cygwin installer. On mac I think "brew install autoconf" is easiest if you are into that. If all else fails, downloading the source [1] and building is pretty easy and straightforward too.
> /Erik
> [1] http://ftp.gnu.org/gnu/autoconf/autoconf-2.69.tar.gz
> On 2016-05-04 16:13, Jim Laskey (Oracle) wrote:
>> Correct.  How do I set up autogen so I can apply these changes?
>>> On May 4, 2016, at 11:11 AM, Erik Joelsson <erik.joelsson at oracle.com> wrote:
>>> Build changes look ok to me, but I also helped write most of them.
>>> This certainly adds some build complexity and might seem overly so for just this optimization. As I understand it, the plan is to expand this build time profiling concept to generate more profile data that can be used by for example jlink plugins.
>>> /Erik
>>> On 2016-05-04 15:36, Claes Redestad wrote:
>>>> Hi,
>>>> please review this change to generate classlists at build-time
>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8150044
>>>> webrevs:
>>>> top: http://cr.openjdk.java.net/~redestad/8150044/top.01/
>>>> jdk: http://cr.openjdk.java.net/~redestad/8150044/jdk.01/
>>>> hotspot: http://cr.openjdk.java.net/~redestad/8150044/hotspot.01/
>>>> The implementation generates an interim image consisting of a minimal
>>>> set of modules, then use this to run a small generator program to
>>>> load common utilities and facilities and dump the result of this to a
>>>> classlist that is then bundled with the final images.
>>>> The smaller number of classes on the default classlist (~1100 instead
>>>> of ~2500) requires some adjustment to the metaspace defaults.
>>>> This achieves the following:
>>>> - Removes a manual, error-prone process to update the versioned
>>>>  classlists
>>>> - Ensures the classlists shipped with the JDK/JRE is up to date
>>>>  with recent JDK changes, e.g., when moving classes from sun.* to
>>>>  jdk.internal.*
>>>> - Automatically picks up and incorporates the output of jlink plugins
>>>>  such as GenerateJLIClassesPlugin into the classlist
>>>> - Supports cross-compilation build targets, although it runs using a
>>>>  build JDK that can run on the host platform to generate such
>>>>  classlists (this isn't ideal, but no worse than the current
>>>>  situation, where the versioned classlist for the host platform is
>>>>  simply copied to the cross-compiled target)
>>>> There are a few concerns/drawbacks:
>>>> - It does add complexity to the build, and concern has been voiced that
>>>>  this would adversely affect build times. However, I'm happy to say
>>>>  that on my machine build times are roughly the same:
>>>> Before:
>>>> real    2m37.303s
>>>> user    35m33.576s
>>>> sys    3m46.476s
>>>> After:
>>>> real    2m36.168s
>>>> user    35m31.232s
>>>> sys    3m52.268s
>>>> (real time varies ± 5s from build to build)
>>>> - Startup on the specific applications we've used to generate the
>>>>  classlists for previously suffer small regressions. These are
>>>>  specifically rather dated AWT and Swing-based applications. OTOH,
>>>>  startup characteristics generally improve on other applications
>>>>  (minimal VM, jetty, etc...)
>>>> Testing: JPRT -testset hotspot
>>>> Thanks!
>>>> /Claes

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