This is a test bug.

When running test/jdk/jdk/internal/platform/cgroup/TestCgroupMetrics.java on ubuntu 21.10, this test looks for a named value "nr_periods" in the file /sys/fs/cgroup/..../cpu.stat

However, if this file exists but doesn't contain this named value, the following code fails:

    private long getLongValueEntryFromFile(String file, String metric) {
        Path filePath = Paths.get(UNIFIED.getPath(), file);
        try {
            String strVal = Files.lines(filePath).filter(l -> l.startsWith(metric)).collect(Collectors.joining());
            String[] keyValues = strVal.split("\\s+");
            String value = keyValues[1]; <<< HERE
            return convertStringToLong(value);
        } catch (IOException e) {
            return NOT_AVAILABLE;
        }
    }



java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1
at jdk.test.lib.containers.cgroup.MetricsTesterCgroupV2.getLongValueEntryFromFile(MetricsTesterCgroupV2.java:125)
at jdk.test.lib.containers.cgroup.MetricsTesterCgroupV2.testCpuSchedulingMetrics(MetricsTesterCgroupV2.java:324)
at jdk.test.lib.containers.cgroup.MetricsTester.testAll(MetricsTester.java:59)
at TestCgroupMetrics.main(TestCgroupMetrics.java:47)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:578)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:312)
at java.base/java.lang.Thread.run(Thread.java:828)