RFR: 8366658: Add missing locks when accessing the VirtualMemoryTracker instance in tests and MemMapPrinter

[David Holmes]

On Tue, 2 Sep 2025 07:07:51 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

> Hi,
> 
> This PR adds the missing locks for the tests and MemMapPrinter, also fixes a small bug in `walk_virtual_memory`. See inline review comments.
> 
> Passes tier1.

src/hotspot/share/nmt/virtualMemoryTracker.hpp line 347:

> 345: 
> 346: class VirtualMemoryWalker : public StackObj {
> 347: public:

Suggestion:

 public:

The access modifier should be indented by 1

test/hotspot/gtest/runtime/test_committed_virtualmemory.cpp line 50:

> 48:       MemTracker::NmtVirtualMemoryLocker nvml;
> 49:       VirtualMemoryTracker::Instance::snapshot_thread_stacks();
> 50:     }

Why two separate locking blocks?

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PR Review Comment: https://git.openjdk.org/jdk/pull/27038#discussion_r2342779331
PR Review Comment: https://git.openjdk.org/jdk/pull/27038#discussion_r2342780510