RFR: 8366457: Add ResourceArea and Arena allocators for the RBTree

[Casper Norrbin]

On Wed, 7 Jan 2026 09:37:50 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

> This PR adds Arena and ResourceArea allocators to the RBTree. The test checks that we can make RBTrees from these allocators and that a basic upsert works.

Looks good! Thank's for adding these. Only got one small nit.

src/hotspot/share/utilities/rbTree.hpp line 35:

> 33: #include "nmt/memTag.hpp"
> 34: #include "runtime/os.hpp"
> 35: #include "runtime/thread.hpp"

Do we need to include `allocation.hpp` and `thread.hpp`? I can't find what's using these and it builds fine for me with those includes removed.

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PR Review: https://git.openjdk.org/jdk/pull/29082#pullrequestreview-3643625475
PR Review Comment: https://git.openjdk.org/jdk/pull/29082#discussion_r2675924268