RFR: 8157023: Integrate NMT with JFR [v3]

[Stefan Johansson]

On Tue, 6 Dec 2022 12:18:04 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Stefan Johansson has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Special snapshot for NMT events in JFR
>
> src/hotspot/share/services/memSnapshot.cpp line 68:
> 
>> 66:     total_arena_size +=  mm->arena_size();
>> 67:   }
>> 68:   assert(total_arena_size == ms->total_arena(), "Mismatch in accounting");
> 
> Could fail intermittently since all counters are updated asynchronously. The snapshot can be modified below us while we assemble this MemSnapshot. I think that's fine, but I would just use the accumulated counter here.

Good point, was about to add other verification as well but stayed away just because of this issue. But didn't think about it when I added this.

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PR: https://git.openjdk.org/jdk/pull/11449