RFR: 8367332: Replace BlockTree tree logic with an intrusive red-black tree

[Johan Sjölen]

On Fri, 14 Nov 2025 11:52:08 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> I saw this just now. I guess this makes sense, but I admit I feel a bit apprehensive about this. Is the RBTree already mature enough? Have we ironed out all issues?
> 
> Can you please test:
> 
>     * that the number of freeblock nodes stays the same pre- and post-patch? (Easiest would be with VM metaspace, I think I print out freeblock statistics somewhere)
> 
>     * that the number of malloc blocks from Metaspace stays the same or that we can explain differences for a simple test? (the old tree lived completely in metaspace and needed no secondary structures; I just want to make sure its still the case. I have not looked at the new RB tree implementation for a while).

We can await RDP1 and integrate this after that. It's closing in on that anyway.

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PR Comment: https://git.openjdk.org/jdk/pull/27212#issuecomment-3532406021