RFR: 8292329: Enable CDS shared heap for zero builds

Tue Aug 23 16:59:28 UTC 2022

On Tue, 23 Aug 2022 16:34:06 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> Stupid question, does that not mean that the CDS dump generated at build time is not usable with the VM at runtime if that is started with default options?

The CDS archive is still useable.

- If G1 is used at runtime, the shared heap is mmaped
- If a non-G1 collector is used, all the objects in the shared heap will be copied into the Java heap.

See comments near `HeapShared::can_use()`:

https://github.com/openjdk/jdk/blob/d24b7b7026cf85f1aecf44f60819762872cfd5c1/src/hotspot/share/cds/heapShared.hpp#L151-L157

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PR: https://git.openjdk.org/jdk/pull/9984