[11u] Backport JEP 346 : Promptly Return Unused Committed Memory from G1

[Andrew Haley]

On 4/4/20 8:24 AM, Gil Tene wrote:

> - Are there any indications that Oracle is backporting this into
> their Oracle JDK 11?
>
> - Do we have input from the GC team on the complexity and potential
> tie-in or dependence [explicit or implied] of this JEP
> implementation on other post-11 G1 improvements, changes,
> assumptions, or invariant modifications?
>
> - What level of extensive review by GC experts and exhaustive GC
> stress-testing are we willing to put in to gain confidence that this
> will not regress the stability of 11u?

All good questions.

The idea of the rolling updates model of OpenJDK is to allow the rapid
development and release of features such as these, and because Java is
almost entirely backwards compatible, users can choose a modern but
less-tested release or a stable long-term release. If we were to
backport substantial changes such as this to the stable 11u branch we
would take away that choice from our users. Reluctantly, therefore, I
must say no, because our users need to be able to make that choice.

Maybe there is an argument to be made for a "jdk11u-performance"
release of OpenJDK 11, which would be distinct from the stable
release.

-- 
Andrew Haley  (he/him)
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
https://keybase.io/andrewhaley
EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671