RFR: 8330027: Identity hashes of archived objects must be based on a reproducible random seed

[Calvin Cheung]

On Thu, 11 Apr 2024 09:24:16 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> CDS archive contains archived objects with identity hashes.
> 
> These hashes are deliberately preserved or even generated during dumping. They are generated based on a seed that is initialized randomly on a per-thread basis. These generations precede CDS dump initialization, so they are not affected by the init_random call there, nor would they be affected by [JDK-8323900](https://bugs.openjdk.org/browse/JDK-8323900).
> 
> A random seed will not work for dumping archives since it prevents reproducible archive generation. Therefore, when dumping, these seeds must be initiated in a reproducible way.

Looks good.
nit: please update copyright header in thread.hpp.

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Marked as reviewed by ccheung (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18735#pullrequestreview-2004471274