Questions about Shedandoah and OpenJDK

[Roman Kennke]

Hi Francisco,

First of all, we do not really have a versioning scheme for Shenandoah.
We came to call the new Shenandoah features load-reference-barriers
(LRB) and the new forwarding pointer scheme 'Shenandoah 2.0' because it
is such a dramatic change in the algorithm and its properties. So,
terminology here is everything before LRB is '1.0' and everything after
'2.0'.

> 1) How do I know which version of the Shenandoah JVM GC is part of any
> particular version of the OpenJDK?

> 2) Which versions of the OpenJDK have the Shenandoah JVM GC version
> 1.0 and which versions of the OpenJDK have the Shenandoah JVM GC 2.0?

LRB and new fwd pointer scheme have been pushed to JDK 13, and is
available there. (Except Oracle builds, but that is another story.)

We have also backported it to our own shenandoah/jdk11 repository, and
that is available in RHEL OpenJDK packages.

We've also backported it to shenandoah/jdk8, but this hasn't been
released as binary yet.

The Shenandoah GC in JDK 12 does not have the new features, and never will.

Eventually we will propose Shenandoah GC for inclusion in JDK 11 updates
and JDK 8 updates, but we don't know when that will happen, and whether
it will be accepted or not.

Does that answer your questions?

Thanks,
Roman