Lilliput impact on startup time

[Georgios Andrianakis]

Thanks a lot for the information Roman!

I will try Alexey's builds and report back if there are any issues.

On Mon, Nov 25, 2024 at 6:16 PM Kennke, Roman <rkennke at amazon.de> wrote:

> Hi Georgios,
>
> This is a peculiarity with the Oracle builds. Oracle has decided to not
> generate CDS archives with compact headers in their builds:
> https://bugs.openjdk.org/browse/JDK-8341553
>
> Other vendors are free to generate compact-headers-CDS-archives, and,
> afaik, it is on-by-default in OpenJDK sources.
>
> FWIW, the COH-CDS archives are generated in Aleksey’s build, you may want
> to give them a try:
> https://builds.shipilev.net/openjdk-jdk/
>
> Roman
>
>
> > Thanks a lot for the tip!
> > Indeed, forcing the creation of the archive eliminates the regression in
> startup time.
> >
> > So now my question becomes, will this process be necessary even when JDK
> 24 ships, or will the archive be part of the release so users don't have to
> create it manually?
> >
> > On Mon, Nov 25, 2024 at 4:44 PM Stefan Karlsson <
> stefan.karlsson at oracle.com> wrote:
> > Hi Georgios,
> >
> > The regression seems to come from the lack of CDS. I see similar
> regressions when I run with -Xshare:off.
> >
> > I guess that these EA builds don't include the CDS archive for compact
> object headers:
> > $ time jdk-24-ea-b25/bin/java -XX:+UnlockExperimentalVMOptions
> -XX:+UseCompactObjectHeaders -Xlog:cds*=trace -version
> > [0.012s][info][cds] trying to map
> /home/stefank/java/jdk-24-ea-b25/lib/server/classes_coh.jsa
> > [0.012s][info][cds] Specified shared archive not found
> (/home/stefank/java/jdk-24-ea-b25/lib/server/classes_coh.jsa)
> > [0.012s][info][cds] Initialize static archive failed.
> > [0.012s][info][cds] Unable to map shared spaces
> >
> > Try to first dump the CDS archive with:
> > $ jdk-24-ea-b25/bin/java -XX:+UnlockExperimentalVMOptions
> -XX:+UseCompactObjectHeaders -Xshare:dump -version
> >
> > After I have run that I get the CDS archive:
> > $ time jdk-24-ea-b25/bin/java -XX:+UnlockExperimentalVMOptions
> -XX:+UseCompactObjectHeaders -Xlog:cds*=trace -version
> > [0.011s][info][cds] trying to map
> /home/stefank/java/jdk-24-ea-b25/lib/server/classes_coh.jsa
> > [0.011s][info][cds] Opened archive
> /home/stefank/java/jdk-24-ea-b25/lib/server/classes_coh.jsa.
> > [0.011s][info][cds] Archive was created with UseCompressedOops = 1,
> UseCompressedClassPointers = 1, UseCompactObjectHeaders = 1
> > ...
> >
> > Could you try and see if that helps the startup times for you?
> >
> > Cheers,
> > StefanK
> >
> > On 2024-11-25 15:22, Georgios Andrianakis wrote:
> >> Hi folks,
> >>
> >> I just tried the Lilliput (JEP 450) using the latest OpenJDK 24 EA
> build on a sample Quarkus application to see how beneficial Lilliput can be
> for us.
> >>
> >> On my machine (a Ryzen 5950X running Linux) with Lilliput disabled, the
> application starts up in around 600ms and consumes around 140MB of RSS
> memory (before the application handles any traffic).
> >> With Lilliput enabled (via  -XX:+UnlockExperimentalVMOptions
> -XX:+UseCompactObjectHeaders) I see RSS falling to around 130MB which is
> really nice!
> >> However I also see a startup regression of around 30ms (approximately
> 5%). Is this something that is expected?
> >>
> >> Thanks!
> >>
> >> P.S. Apologies if this is not the correct mailing list for Lilliput
> related topics
> >>
> >> --
> >> Georgios Andrianakis
> >> Independent Contractor
> >>
> >
> >
> >
> > --
> > Georgios Andrianakis
> > Independent Contractor
>
>
>
>
>
> Amazon Web Services Development Center Germany GmbH
> Krausenstr. 38
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>


-- 

Georgios Andrianakis

Independent Contractor
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