[21u] Backport intention of 8322420: [Linux] cgroup v2: Limits in parent nested control groups are not detected

[Severin Gehwolf]

Hi,

On Wed, 2025-03-26 at 22:07 +0800, Jan Kratochvil wrote:
> Hello Severin,
> 
> is there some plan whether it could be backported and its schedule?

Let's consider it for JDK 21u. But it'll require some planning.

> On Thu, 20 Feb 2025 21:05:04 +0800, Jan Kratochvil wrote:
> > On Sat, 15 Feb 2025 02:05:38 +0800, Severin Gehwolf wrote:
> > > JDK 24 hasn't been officially released yet, so the proposed patches
> > > haven't seen much real-world usage yet.
> > 
> > OK.
> 
> JDK 24 has been released now. Do you find its real world testing sufficient
> for a backport into OpenJDK 21.0.8 with its expected GA in July?

It being released is not sufficient IMO, no. The ecosystem needs some
time to pick it up. Looking at the schedule we'd get around 2 months
bake time in 24 (after GA) before we bring it into 21 which seems ok.

Looking at the schedule for the next JDK 21 updates, I'd propose to
target this for 21.0.9 in October. The initial development starts end
of May (in about two months). At that time PRs should be ready for
approval. Please coordinate with reviewers to agree to that. Getting
this in early in the development cycle of a JDK 21 updates release
seems prudent so as to increase the chance of catching some bugs before
rampdown.

Looking at the initially proposed list of patches, it appears not all
of them make sense to bring in as a dependency. Please take another
look and propose a minimal set of bugs that we absolutely need to
backport for this. It would be good if we could reduce the set of bugs
to:

- <https://github.com/openjdk/jdk/commit/e889b460c03b3887ec5477fa734c430d3c3a41c8>
  <https://bugs.openjdk.org/browse/JDK-8327071> [Testbug] g-tests for cgroup leave files in /tmp on linux
  1 file changed, 10 insertions(+), 1 deletion(-)

- <https://github.com/openjdk/jdk/commit/3d4eb159e6d597f37081faf21b7e3f0f1af299e5>
  <https://bugs.openjdk.org/browse/JDK-8302744> Refactor Hotspot container detection code
  10 files changed, 862 insertions(+), 590 deletions(-)

- <https://github.com/openjdk/jdk/commit/d0052c032cc1927e7e92f04cfedab20e0c4e0293>
  <https://bugs.openjdk.org/browse/JDK-8333326> Linux Alpine build fails after 8302744
  1 file changed, 9 insertions(+), 5 deletions(-)

- <https://github.com/openjdk/jdk/commit/0a6ffa57954ddf4f92205205a5a1bada813d127a>
  <https://bugs.openjdk.org/browse/JDK-8261242> [Linux] OSContainer::is_containerized() returns true when run outside a container
  18 files changed, 290 insertions(+), 63 deletions(-)

- <https://github.com/openjdk/jdk21u-dev/pull/1330/commits/1ceeb18e6fbf9a7851499b89cba34544ddbcd6dc>
  src/java.base/linux/native/libjava/CgroupMetrics.c:42:(.text+0x11): undefined reference to `JVM_IsContainerized'
  a patch by Yuri Nesterenko, it is not needed in recent JDKs due to <https://bugs.openjdk.org/browse/JDK-8017234>
  1 file changed, 1 insertion(+)

- <https://github.com/openjdk/jdk/commit/153b12b9df87fdf8122cae3bf7f13078f55f7101>
  <https://bugs.openjdk.org/browse/JDK-8331560> Refactor Hotspot container detection code so that subsystem delegates to controllers
  8 files changed, 511 insertions(+), 264 deletions(-)

- <https://github.com/openjdk/jdk/commit/38bd8a36704a962f0ad1052fd2ec150a61663256>
  <https://bugs.openjdk.org/browse/JDK-8338236> Compile error in cgroup code on Linux when using clang
  2 files changed, 5 insertions(+), 5 deletions(-)

- <https://github.com/openjdk/jdk/commit/12d060a255b9b783488714c6c2cb73a899d3f708>
  <https://bugs.openjdk.org/browse/JDK-8339148> Make os::Linux::active_processor_count() public
  unclean but obvious
  1 file changed, 1 insertion(+), 3 deletions(-)

- <https://github.com/openjdk/jdk/commit/55a7cf14453b6cd1de91362927b2fa63cba400a1>
  <https://bugs.openjdk.org/browse/JDK-8322420> [Linux] cgroup v2: Limits in parent nested control groups are not detected
  9 files changed, 362 insertions(+), 111 deletions(-)

Thanks,
Severin