RFR: 8297718: Make NMT free:ing protocol more granular [v2]
Gerard Ziemski
gziemski at openjdk.org
Wed Dec 7 20:10:14 UTC 2022
On Thu, 1 Dec 2022 13:59:25 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:
>> This PR avoids the double registration of a failed `os::realloc` in NMT by doing the NMT free protocol steps inline (asserting block integrity, marking of MallocHeader, and registrering results to statistics). This is done by creating a new struct `FreePackage` which includes all of the necessary data for registrering results.
>>
>> I also did some light refactoring which I think makes the protocol clearer, these are done piece wise as separate commits for the reviewers' convenience.
>
> Johan Sjölen has updated the pull request incrementally with 10 additional commits since the last revision:
>
> - Add test that asserts block integrity after revival
> - Make MallocHeader NONCOPYABLE
> - Rest of it
> - Adjust comments
> - Put back comment, suitably rewritten
> - Note reversibility of mark_block_as_dead
> - Rename record_free_block to record_free
> - Rename record_free to deaccount
> - Move FreePackage into MallocHeader and rename
> - Rename as revive, delete copy ctr
Marked as reviewed by gziemski (Committer).
src/hotspot/share/runtime/os.cpp line 732:
> 730: // We have however marked it as dead, revert this change.
> 731: header->revive();
> 732: return nullptr;
This is the very first usage of `nullptr` instead of `NULL`, and we now have a mix of both.
Was this a deliberate choice? Should we then switch all `NULLs` to `nullptr` in here?
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PR: https://git.openjdk.org/jdk/pull/11390
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