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From "Winnebeck, Jason" <>
Subject RE: Groovy AOT compilation
Date Mon, 08 May 2017 15:35:12 GMT
I think a biggest question than AOT compatibility is why does compile static still need to
do reflection? I thought that was the point was to disable it, especially for Android support…?
Unless the issue is the metaclass generation, does compile static still generate metaclasses?


From: Paolo Di Tommaso []
Sent: Monday, May 08, 2017 11:02 AM
Subject: Groovy AOT compilation

Dear all,

I just want to share with you my experience with the Java AOT compiler<>
a came across a few days ago.

Although they said clearly that it still an experimental project and it does not support dynamic
class loading and most of reflection, I turns out it's possible to compile a basic static
Groovy class, eg:

class Hello {

  static void main( String... args ) {
    System.out.println "Hello world!"

This mean that it creates a native 5MB binary executable, that can run on any machine without
the need of the Java VM nor the Groovy runtime! in 12 millisecond! cool!!

Unfortunately the good news stops here. I was unable to successfully compile any other piece
of code, which for example uses a Groovy "println" method or just instantiate a class. The
problem seems to be that, even though the code is statically compiled, Groovy uses reflection
behind the scene to instantiate classes and performs other operations.

Now, I guess this is certainly not a Groovy top priority, however since there is an on-going
discussion around a major Groovy reengineering to make it compatible with the upcoming Java
9 module system, I was wondering if it would not make sense to include the support for the
Java AOT compiler as a goal for a future Groovy 3/4 release?

Personally I think it would be an extremely useful feature and a major achievement for the

What do you think ?


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