RFR: 8370572: Cgroups hierarchical memory limit is not honored after JDK-8322420 [v2]

[Aleksey Shipilev]

On Wed, 29 Oct 2025 09:36:54 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

> Without a proper regression test this is bound to fall through the cracks again. So are you sure this cannot be tested? It should be fine if the test needs root privileges (we could skip it if not root). But it would be better than not having one.

Yes, I tried to write a test, but it was not simple at all. AFAICS, you need to configure the _host_ in a particular way to get to the interesting configuration, when part of hierarchy is hidden. So not only it would require root, it would also make changes to the host cgroup config (and properly revert them at the end of testing!). It would be better if we could come up with something like Docker-in-Docker kind of test, but that is probably a headache as well.

Anyway, we are dealing with the real-world, customer-facing breakage here, so I reasoned it was unwise to delay the immediately deployable fix, just because it was unclear how to write a reliable regression test for it :)

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PR Comment: https://git.openjdk.org/jdk/pull/28006#issuecomment-3461156992