These internal methods were implemented in order to expose container metrics to via a public API. I’ve filed JDK-8203359 and JDK-8199944 to add an MBean and JFR events that will expose these values.
JDK-8203359: Java Flight Recorder (JFR) improvements for containers JDK-8199944: Add Container MBean to JMX There are container tests that verify many of these methods. Can you give me a list of the metrics that are not available under cgroupv2? Bob. > On Sep 18, 2019, at 10:02 AM, Severin Gehwolf <sgehw...@redhat.com> wrote: > > Hi Bob, > > As you probably know, I'm looking at cgroups v2 support[0] in OpenJDK. > When looking at Metrics.java[1] I see that many methods aren't used > anywhere. Neither in tests nor in actual code. It looks like as if the > interface has been modelled along the lines of the cgroups v1 > implementation. These methods are: > > - public long getCpuUsage(); > - public long[] getPerCpuUsage(); > - public long getCpuUserUsage(); > - public long getCpuSystemUsage(); > - public double getCpuSetMemoryPressure(); > - public long getMemoryMaxUsage(); > - public long getMemoryUsage(); > - public long getKernelMemoryFailCount(); > - public long getKernelMemoryMaxUsage(); > - public long getKernelMemoryUsage(); > - public long getTcpMemoryFailCount(); > - public long getTcpMemoryMaxUsage(); > - public long getTcpMemoryUsage(); > - public long getBlkIOServiceCount(); > - public long getBlkIOServiced(); > > They are essentially dead code. Note that not all of them would have an > implementation in cgroups v2. With that in mind, does it actually make > sense for the Metrics interface to define those? We could keep the > implementations for cgroup v1 Metrics, but perhaps remove them from the > interface? It seems the current Metrics interface defines too many > methods for no good reason. Am I missing something? Thoughts? > > From the looks of it it wouldn't even require a CSR as > jdk.internal.platform isn't an exported package. > > Here is an example patch removing them, and jdk docker container tests > still pass: > http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8230305/remove_metrics_interface_methods.patch > > Thanks, > Severin > > [0] https://bugs.openjdk.java.net/browse/JDK-8230305 > [1] > http://hg.openjdk.java.net/jdk/jdk/file/377f47ccc20b/src/java.base/share/classes/jdk/internal/platform/Metrics.java >
