Hello from JRuby and here's another crash

[Charles Oliver Nutter]

The patched build does indeed work, and cuts JRuby's base startup time by
50%! Bravo!

$ time jruby -e 1
jruby -e 1  3.53s user 0.14s system 276% cpu 1.326 total
$ time jruby -J-XX:CacheDataStore=jruby.cds -e 1
jruby -J-XX:CacheDataStore=jruby.cds -e 1  2.38s user 0.19s system 385% cpu
0.667 total

This is a very promising start and the largest single improvement we have
seen. Comparison with our previous champion, C1:

$ time jruby --dev -e 1
jruby --dev -e 1  1.22s user 0.09s system 142% cpu 0.922 total

Interestingly, when I try to use the previously trained CDS dump (via
100.times { org.jruby.Ruby.newInstance }) with a command line that forces
C1 (--dev flag passes -XX:TieredStopAtLevel=1) I get a different crash:
https://gist.github.com/headius/d3138efa52eed9c678414c8cfe08af27

I'm wondering what else I can do to try to train the CDS dump better, so
that a larger command (jruby -S gem list) sees more improvement (this loads
a bunch more Ruby code into the interpreter):

$ time jruby -S gem list > /dev/null
jruby -S gem list > /dev/null  6.41s user 0.26s system 236% cpu 2.821 total
$ time jruby -J-XX:CacheDataStore=jruby.cds -S gem list > /dev/null
jruby -J-XX:CacheDataStore=jruby.cds -S gem list > /dev/null  5.84s user
0.32s system 294% cpu 2.089 total

- Charlie

On Thu, Jul 4, 2024 at 11:50 PM <ioi.lam at oracle.com> wrote:

> Hi Charlie,
>
> Thanks for the bug report.
>
> It turns out some Leyden optimizations can't handle the module options
> specified by jruby, such as these:
>
>     --add-opens=java.base/java.nio.channels=org.jruby.dist
>     --module-path=/xxxx/jruby-9.4.8.0/lib/jruby.jar
>
> I filed https://bugs.openjdk.org/browse/JDK-8335735
>
> I'll work on a proper fix. Meanwhile, I have a work-around in this branch
>
>
> https://github.com/iklam/jdk/tree/work-around-8335735-jruby-crash-due-to-lack-of-module-support
>
> If you build a JDK from this source branch, you can see the following
> improvements:
>
> # [1] No optimizations
> $ time env JAVA_HOME=$MYJAVA ~/Downloads/ruby/jruby-9.4.8.0/bin/jruby \
>     -e '10.times { org.jruby.Ruby.newInstance }'
> real   0m3.215s
> user   0m14.868s
> sys    0m0.373s
>
>
> # [2] Leyden
> $ time env JAVA_HOME=$TBP0 ~/Downloads/ruby/jruby-9.4.8.0/bin/jruby \
>     -J-XX:CacheDataStore=jruby.cds \
>     -e '10.times { org.jruby.Ruby.newInstance }'
> real   0m1.880s
> user   0m9.001s
> sys    0m0.268s
>
>
> # [3] Compare with CDS in the JDK mainline
> $ env JAVA_HOME=$MYJAVA ~/Downloads/ruby/jruby-9.4.8.0/bin/jruby \
>      -J-XX:DumpLoadedClassList=jruby.classlist \
>      -e '10.times { org.jruby.Ruby.newInstance }'
> $ $MYJAVA/bin/java -Xshare:dump \
>     --module-path=/home/iklam/Downloads/ruby/jruby-9.4.8.0/lib/jruby.jar \
>     -XX:SharedClassListFile=jruby.classlist \
>     -XX:SharedArchiveFile=jruby.jsa -Xlog:cds
> $ time env JAVA_HOME=$MYJAVA ~/Downloads/ruby/jruby-9.4.8.0/bin/jruby \
>     -J-XX:SharedArchiveFile=jruby.jsa \
>     -e '10.times { org.jruby.Ruby.newInstance }'
> real   0m2.628s
> user   0m13.007s
> sys    0m0.428s
>
> Please try it out and let us know if you run into other problems.
>
> Thanks
>
> - Ioi
>
>
> On 7/4/24 1:06 PM, Charles Oliver Nutter wrote:
>
> Hello friends! Long time lurker, first time poster.
>
> Like others I was excited to hear that the first EA of Leyden had dropped.
> Sadly, I have another crash to report.
>
> I see there are two other crashes reported, but mine appears different
> (ClassPrelinker::is_indy_resolution_deterministic):
>
> https://gist.github.com/headius/79c6460ed55c1d80c82e1c0209897e24
>
> Perhaps unsurprisingly, the additional flags provided by Vladimir Kozlov (-XX:+UnlockDiagnosticVMOptions
> -XX:-ReduceAllocationMerges) did not appear to change the result.
>
> This is with JRuby's minimally invokedynamic-based mode, which has given
> us the shortest startup time in the past (second only to disabling tiers
> 2-4 and staying in C1).
>
> I am on MacOS AArch64 Sonoma 14.5, testing against JRuby master, but
> reproduction should be as easy as downloading the JRuby binary tarball,
> unpacking, and running bin/jruby with the command line above.
>
> https://www.jruby.org/download
>
> I am eager to work with Leyden folks to investigate issues, and I am
> planning to be at JVMLS this year to discuss collaborating more!
>
> - Charlie
>
>
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