RFR: 8345423: Shenandoah: Parallelize concurrent cleanup

[Y. Srinivas Ramakrishna]

On Wed, 9 Apr 2025 20:17:55 GMT, William Kemper <wkemper at openjdk.org> wrote:

> Not clean

minor nit in comment. Ok not to fix if the issue also in upstream (likely), so as to avoid conflicts.

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Marked as reviewed by ysr (Committer).

PR Review: https://git.openjdk.org/shenandoah-jdk21u/pull/172#pullrequestreview-2758547547