Availability of Shenandoah 2.0 in JDK

Question

In [1, page 16] Aleksey Shipilёv says that Shenandoah 2.0 is available in JDK 13 GA. But in the Complete JDK 13 Release Notes [2] (including JDK 13 GA, JDK 13.0.1 GA, JDK 13.0.2 GA), Shenandoah is not mentioned.

Question: What is the current status of Shenandoah 2.0 in JDK GA? Is it available in JDK 13 GA, or, if not, for which release is it planed?

[1] https://shipilev.net/talks/jugbb-Sep2019-shenandoah.pdf

[2] https://www.oracle.com/technetwork/java/javase/13all-relnotes-5461743.html

Answer 1

Oracle famously does not ship Shenandoah in either their proprietary Oracle JDK downstream, or their OpenJDK builds. For that matter, Oracle does not list any Shenandoah-related release notes for their builds -- that is the link you have. You want JDK 13 from any other OpenJDK vendor and look into their release notes. Automatically-generated release notes for the vanilla OpenJDK 13u can be seen here, generated by myself -- there are the whole lot of RNs for Shenandoah in hotspot/gc section.

"Shenandoah 2.0" indeed ships starting from JDK 13, and it was also backported to Red Hat 11u and 8u downstreams, at 11.0.5+ and 8u242+, respectively. Recently, the proposal to contribute it to 11u upstream was made.

See more details in the relevant section of Shenandoah wiki.

Answer 2

Oracle does not support it, try downloading Oracle JDK and enabling it : -XX:+UseShenandoahGC, it will not work; it will though, if you get AdoptOpenJDK.