RFR: 8369622: GlobalChunkPoolMutex needs to be recursive

[Johan Sjölen]

On Mon, 13 Oct 2025 06:19:42 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> The GlobalChunkPoolMutex replaced ThreadCritical in [JDK-8356173](https://bugs.openjdk.org/browse/JDK-8356173). In NMT, we can unfortunately reach a recursive locking situation in situations when the VM is crashing and NMT attempts to perform a error report. I suggest that we make this particular mutex recursive, until we can resolve the design issues that causes this.
>> 
>> This PR also replaces the static initialization with `DeferredStatic`, and fixes the indentation of access modifiers to be consistently 0-indented.
>> 
>> Please note that we do not take the lock in NMT in order to allocate memory, but in order to have a "static picture" of the arena counters.
>
> src/hotspot/share/memory/arena.cpp line 49:
> 
>> 47: 
>> 48: ChunkPoolLocker::ChunkPoolLocker() {
>> 49:   assert(GlobalChunkPoolMutex != nullptr, "must be initialized");
> 
> Do we have an equivalent assertion to replace this with?

Yes, it's inside of the getter in `DeferredStatic` (so it's "fixed" by the class abstraction)

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PR Review Comment: https://git.openjdk.org/jdk/pull/27759#discussion_r2425344502