Projects, which use JSR292

[Charles Oliver Nutter]

I also need to say this: PUT ME TO WORK :)

I'm very eager to start showing off invokedynamic and make it
pervasive throughout JRuby (or as pervasive as possible while still
supporting Java 6). Tell me what I need to do to help!

- Charlie

On Fri, Feb 18, 2011 at 2:06 PM, Charles Oliver Nutter
<headius at headius.com> wrote:
> On Fri, Feb 18, 2011 at 7:19 AM, Christian Thalinger
> <christian.thalinger at oracle.com> wrote:
>> What I can tell so far is that setting rubyDirect=true inlines a whole lot more stuff than without.  I looks like it wants to inline all recursive calls of fib_ruby into a single method, which doesn't work very well, hitting two limits: NodeCountInliningCutoff and DesiredMethodLimit.
>>
>> I tried to bump these limits but that is a dead end for the compiler since at one point it skips the compile because it gets too many nodes:
>>
>>  43   COMPILE SKIPPED: out of nodes parsing method (not retryable)
>>
>> I don't know why it wants to inline all these recursive calls.  Is that something JRuby tries to do?
>
> Nope, we're not doing anything special there. Here's the basic layout
> (review for you perhaps):
>
> Prior to this work, invokedynamic connected the call sites up to our
> existing DynamicMethod objects via the "call" method. In most cases,
> those objects were a unique class per method, to allow things to
> inline, but ultimately they added one or two intermediate frames to
> every indy call path. You can see that in my previous email.
>
> In between then and now, I worked on "dynopt". Dynopt in JRuby
> basically takes the last-seen method at a call site while interpreting
> and inserts a guard, direct call to that method (*really*
> direct...invokevirtual or invokestatic), and fallback to the old call
> site logic. This worked for native core methods with fixed arities and
> no closure, a few "intrinsics", self-recursing calls (fib, tak), and
> Float and Fixnum dispatches with or without a boxed argument. It also
> inlined directly any trivial leaf methods (constant return value,
> simple state lookups, etc). This work improved the performance of
> small benchmarks substantially, and the largest part of that
> improvement came from being able to directly make recursive calls.
>
> The new indy work in JRuby basically takes the direct-binding part of
> that work and uses it to patch invokedynamic all the way through,
> skipping DynamicMethod. It works for the cases I listed in my email to
> Rémi: basically any fixed-arity, no-block, core class or Ruby-to-Ruby
> calls. Next I was going to explore patching Ruby to Java calls all the
> way through as well.
>
> At *best* this logic does nothing more than remove as many
> intermediate frames between the caller and target. We do no manual
> inlining (except for the trivial leaf cases), and are simply
> connecting A with B.
>
> On the one hand I'm thrilled to see that a lot of stuff is inlining.
> With only a tiny amount of work, Ruby calls can inline into Ruby
> calls, with very little intervening overhead.
>
> But on the other hand, I'm not sure what I should expect to see from a
> performance perspective. "dynopt" inlines Ruby into Ruby as well, at
> the cost of a lot of bytecode in each Ruby method body, eating up that
> precious budget. I would have expected the Ruby-to-Ruby inlining via
> invokedynamic to perform as well or better than dynopt.
>
> I'm not grousing about performance, mind you :) I think it's just
> awesome how cleanly this is working so far with not a whole lot of
> effort. I'm champing at the bit to make all of JRuby
> invokedynamic-aware. But obviously the perf is not as good as we'd
> expect it, and I'm standing by to help provide information or
> experiment to improve it.
>
> FWIW, you can specify jruby.compile.dynopt=true to turn on dynopt for
> benchmarks, if you'd like to compare with indy. It can take longer to
> ramp up, since it forces 100% JIT (no force-compiling the target
> script immediately), which is then subject to a hard 50-invocation
> threshold.
>
> - Charlie
>