RFR: 8304824: NMT should not use ThreadCritical [v9]
Robert Toyonaga
duke at openjdk.org
Mon Oct 28 16:12:39 UTC 2024
> ### Summary
> This PR just replaces `ThreadCritical` with a lock specific to NMT. `ThreadCritical` is a big lock and is unnecessary for the purposes of NMT. I've implemented the new lock with a semaphore so that it can be used early before VM init. There is also the possibility of adding assertions in places we expect NMT to have synchronization. I haven't added assertions yet in many places because some code paths such as the (NMT tests) don't lock yet. I think it makes sense to close any gaps in locking in another PR in which I can also add more assertions.
>
> Testing:
> - hotspot_nmt
> - gtest:VirtualSpace
> - tier1
Robert Toyonaga has updated the pull request incrementally with two additional commits since the last revision:
- add a comment explaining lock rank
- remove unnecessary dropping of tracking level
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/20852/files
- new: https://git.openjdk.org/jdk/pull/20852/files/7ed996e2..976e26c1
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=20852&range=08
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=20852&range=07-08
Stats: 10 lines in 3 files changed: 0 ins; 8 del; 2 mod
Patch: https://git.openjdk.org/jdk/pull/20852.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/20852/head:pull/20852
PR: https://git.openjdk.org/jdk/pull/20852
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