[jdk17u-dev] RFR: 8256844: Make NMT late-initializable

[Thomas Stuefe]

On Wed, 22 Jun 2022 09:31:21 GMT, Vladimir Kempik <vkempik at openjdk.org> wrote:

> Please review this backport to jdk17u-dev
> Doesn't apply clean because of JDK-8280940 backport which introduced the same patch into test_os.cpp

Test changes are okay. 

I'd like to see some mass tests running though, for some days maybe. I'm worried about the changed pre-init allocation mechanics. This patch has been well tested in 18 and beyond, so I may just be paranoid. Just worry about aspects I did not think to test, like native integration.

One small concern I have is that with this patch, we stop recognizing the old `NMT_LEVEL_<pid>` variable. This needs a patch note somewhere (no clue where, @GoeLin ?).

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Marked as reviewed by stuefe (Reviewer).

PR: https://git.openjdk.org/jdk17u-dev/pull/496