RFR: 8369622: GlobalChunkPoolMutex needs to be recursive

[Coleen Phillimore]

On Sun, 12 Oct 2025 12:55:53 GMT, Johan Sjölen <jsjolen 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 43:

> 41: // code and other areas.  For many calls, the current thread has not
> 42: // been created so we cannot use Mutex.
> 43: class RecursivePlatformMutex : public PlatformMutex {

There's already recursive platform Mutex in MutexLocker.hpp

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PR Review Comment: https://git.openjdk.org/jdk/pull/27759#discussion_r2425335088