Tiered compilation leads to "unloaded signature class" inlining failures in JRuby

[Charles Oliver Nutter]

It has been a couple months so I want to wake this thread up again. As
far as I know nothing has changed.

Just to emphasize the importance here: if indy call sites are not
inlining, then JRuby is clearly missing out on tons of performance. It
seems likely to also affect other languages using invokedynamic, and
based on other reports (and my own experiments) it may not matter if
exotic classloader structures are in use.

What is the next step for me to help get this problem solved?

- Charlie

On Mon, Jun 15, 2020 at 4:38 PM Charles Oliver Nutter
<headius at headius.com> wrote:
>
> Charlie Gracie figured out a nice Hotspot incantation to reproduce
> 100% and dump just the PriintInlining graph in question.
>
> He also managed this with tiered compilation *turned off*, so that may
> have been a red herring.
>
> jruby \
>     -Xcompile.invokedynamic \
>     "-J-XX:CompileCommand=option *::*foo*,PrintInlining" \
>     "-J-XX:CompileCommand=compileonly,*::*foo*" \
>     "-J-XX:-TieredCompilation" \
>     main.rb
>
> On Mon, Jun 15, 2020 at 4:23 PM Claes Redestad
> <claes.redestad at oracle.com> wrote:
> > If so, a possible workaround might be to pass the generated class
> > through Unsafe.ensureClassInitialized (or Lookup.ensureInitialized if on
> > 15+)
>
> I added Unsafe.ensureClassInitialized right after the JIT class has
> been defined, and it did not appear to help.
>
> I tried turning off JRuby's background JIT threads, which could cause
> a method to get jitted and loaded twice (into separate classloaders).
> The JRuby flag is "-Xjit.background=false" but it also did not help.
>
> - Charlie