RFR: 8360048: NMT crash in gtest/NMTGtests.java: fatal error: NMT corruption: Block at 0x0000017748307120: header canary broken [v2]

[Gerard Ziemski]

On Tue, 15 Jul 2025 08:29:23 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> So replacing the uses of (sigleton, shared) `VirtualMemoryTracker::Instance` with local `VirtualMemoryTracker vmt(true);` dodges the locking issue, right?

Exactly.

> What confuses me in this patch is why are we doing replacements like:
> 
> ```
> -  site->commit_memory(rgn->committed_size());
> +  site->commit_memory(VirtualMemoryTracker::Instance::committed_size(rgn));
> ```
> 
> Doesn't that introduce dependencies on that singleton instance? Can you confirm that is sane?

I will take a look, but I think the plan now is to come up with a simple fix (since this needs to be backported to jdk25), so it looks like we are not going to push this one (Coleen said you fixed your issue already, so there  is urgency anymore? Please let me know if that is not the case)

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PR Comment: https://git.openjdk.org/jdk/pull/26284#issuecomment-3073496019