RFR: 8367993: G1: Speed up ConcurrentMark initialization [v5]

Thu Jan 22 16:08:04 UTC 2026

On Thu, 22 Jan 2026 14:42:06 GMT, Stefan Johansson <sjohanss at openjdk.org> wrote:

> Did you try doing the initialization here? Would be kind of nice to only initialize CM if ever needed.

This currently does not work because `G1ClearBitmapClosure` unnecessarily calls `G1ConcurrentMark::clear_statistics()` (and `reset_top_at_mark_start()`). There is a CR out for fixing this (https://bugs.openjdk.org/browse/JDK-8376115), but I suggest to not further delay this change.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28723#discussion_r2717568059