RFR: 8365606: Container code should not be using jlong/julong

Fri Oct 10 13:38:57 UTC 2025

On Fri, 10 Oct 2025 13:09:48 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

> Please review this revised version of getting rid of `jlong` and `julong` in internal HotSpot code. The single remaining usage is using `os::elapsed_counter()` which I think is still ok. This refactoring is for the container detection code to (mostly) do away with negative return values.
> 
> It gets rid of the trifold-use of return value: 1.) error, 2) unlimited values 3) actual numbers/values/limits. Instead, all container related values are now being read from the interface files as `uint64_t` and afterwards interpreted in the way that make sense for the API implementations. For example, `cpu` values will essentially be treated as `int`s as before, potentially returning a negative value `-1` for unlimited. For memory sizes the type `physical_memory_size_type` has been chosen. When there is no limit for a specific memory size a value `value_unlimited` is being returned.
> 
> All error cases have been changed to returning `false` in the API functions (and no value is being set in the passed in reference for the value). The effect of this is that all container related functions now return a `bool` and require a reference to be passed in for the `value` that is being asked for.
> 
> All usages of the API have been changed to use the revised API. There is no more usages for `OSCONTAINER_ERROR` (`-2) in HotSpot code.
> 
> While working on this, I've noticed that there are still some calls deep in the cgroup subsystem code to query "machine" info (e.g. `os::Linux::active_processor_count()`). I've filed [JDK-8369503](https://bugs.openjdk.org/browse/JDK-8369503) to get this cleaned-up as this patch was already getting large.
> 
> Testing (looking good):
> - [x] GHA
> - [x] All container tests (including problem listed ones) on Linux x86_64 with cg v1 and cg v2. See [this comment](https://github.com/openjdk/jdk/pull/27743#issuecomment-3390060127) below.
> - [x] Some ad-hoc manual testing in containers using JFR (`jdk.SwapSpace` event) and `VM.info` diagnostic command.
> 
> Thoughts? Opinions?

## Testing details:

**cgroup v2 F42 (docker):**

Passed: containers/cgroup/CgroupSubsystemFactory.java
Passed: containers/cgroup/TestContainerized.java
Passed: containers/docker/DockerBasicTest.java
Passed: containers/docker/ShareTmpDir.java
Passed: containers/docker/TestContainerInfo.java
Passed: containers/docker/TestCPUAwareness.java
Passed: containers/docker/TestCPUSets.java
Passed: containers/docker/TestJcmd.java
Passed: containers/docker/TestJcmdWithSideCar.java
Passed: containers/docker/TestJFREvents.java
Passed: containers/docker/TestJFRNetworkEvents.java
Passed: containers/docker/TestJFRWithJMX.java
Passed: containers/docker/TestLimitsUpdating.java
Passed: containers/docker/TestMemoryAwareness.java
Passed: containers/docker/TestMemoryWithCgroupV1.java
Passed: containers/docker/TestMemoryWithSubgroups.java
Passed: containers/docker/TestMisc.java
Passed: containers/docker/TestPids.java
Passed: containers/systemd/SystemdMemoryAwarenessTest.java
Passed: jdk/internal/platform/cgroup/CgroupV1SubsystemControllerTest.java
Passed: jdk/internal/platform/cgroup/CgroupV2SubsystemControllerTest.java
Passed: jdk/internal/platform/cgroup/TestCgroupMetrics.java
Passed: jdk/internal/platform/cgroup/TestCgroupSubsystemController.java
Passed: jdk/internal/platform/cgroup/TestCgroupSubsystemFactory.java
Passed: jdk/internal/platform/cgroup/TestSystemSettings.java
Passed: jdk/internal/platform/docker/TestDockerBasic.java
Passed: jdk/internal/platform/docker/TestDockerCpuMetrics.java
Passed: jdk/internal/platform/docker/TestDockerMemoryMetrics.java
Passed: jdk/internal/platform/docker/TestDockerMemoryMetricsSubgroup.java
Passed: jdk/internal/platform/docker/TestGetFreeSwapSpaceSize.java
Passed: jdk/internal/platform/docker/TestLimitsUpdating.java
Passed: jdk/internal/platform/docker/TestPidsLimit.java
Passed: jdk/internal/platform/docker/TestSystemMetrics.java
Passed: jdk/internal/platform/docker/TestUseContainerSupport.java
Test results: passed: 34

**cgroup v2 F39 (docker):**

Passed: containers/cgroup/CgroupSubsystemFactory.java
Passed: containers/cgroup/TestContainerized.java
Passed: containers/docker/DockerBasicTest.java
Passed: containers/docker/ShareTmpDir.java
Passed: containers/docker/TestContainerInfo.java
Passed: containers/docker/TestCPUAwareness.java
Passed: containers/docker/TestCPUSets.java
Passed: containers/docker/TestJcmd.java
Passed: containers/docker/TestJcmdWithSideCar.java
Passed: containers/docker/TestJFREvents.java
Passed: containers/docker/TestJFRNetworkEvents.java
Passed: containers/docker/TestJFRWithJMX.java
Passed: containers/docker/TestLimitsUpdating.java
Passed: containers/docker/TestMemoryAwareness.java
Passed: containers/docker/TestMemoryWithCgroupV1.java
Passed: containers/docker/TestMemoryWithSubgroups.java
Passed: containers/docker/TestMisc.java
Passed: containers/docker/TestPids.java
Passed: containers/systemd/SystemdMemoryAwarenessTest.java
Test results: passed: 19

**cgroup v1 RHEL 8 (podman):**

Passed: containers/cgroup/CgroupSubsystemFactory.java
Passed: containers/cgroup/TestContainerized.java
Passed: containers/docker/DockerBasicTest.java
Passed: containers/docker/ShareTmpDir.java
Passed: containers/docker/TestContainerInfo.java
Passed: containers/docker/TestCPUAwareness.java
Passed: containers/docker/TestCPUSets.java
Passed: containers/docker/TestJcmd.java
Passed: containers/docker/TestJcmdWithSideCar.java
Passed: containers/docker/TestJFREvents.java
Passed: containers/docker/TestJFRNetworkEvents.java
Passed: containers/docker/TestJFRWithJMX.java
Passed: containers/docker/TestLimitsUpdating.java
Passed: containers/docker/TestMemoryAwareness.java
Passed: containers/docker/TestMemoryWithCgroupV1.java
Passed: containers/docker/TestMemoryWithSubgroups.java
Passed: containers/docker/TestMisc.java
Passed: containers/docker/TestPids.java
Passed: containers/systemd/SystemdMemoryAwarenessTest.java
Test results: passed: 19; skipped: 1

Note: The skipped test on RHEL 8 is `TestContainerInfo` which checks `cgv2` functionality only.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/27743#issuecomment-3390060127