8226575: OperatingSystemMXBean should be made container aware

[Daniil Titov]

Hi Bob,

>>    It’s too bad getCpuLoad can’t detect that the cpuset is identical to the hosts in order to allow you to fallback to
>>   getSystemCpuLoad0.

I think we can detect that the cpuset is identical to the host's one by comparing the length of the array containerMetrics.getEffectiveCpuSetCpus() returns
to the number of the CPUs configured on the host and returned by  sysconf(_SC_NPROCESSORS_CONF) . The latter could be retrieved by adding new native
 method to OperatingSystemImpl getConfiguredCpuCount0. If they match then we just fallback to getSystemCpuLoad0(). I did some testing on Linux host and
 inside Docker container with different '--cpuset-cpus' settings and it seems to work as expected.

JNIEXPORT jint JNICALL
Java_com_sun_management_internal_OperatingSystemImpl_getConfiguredCpuCount0
(JNIEnv *env, jobject mbean)
{
  if(perfInit() == 0) {
    return counters.nProcs;
  } else {
    return -1;
  }
}


If there is no objection I will include this change in the new webrev.

Thank you,
Daniil

On 12/3/19, 1:30 PM, "Bob Vandette" <bob.vandette at oracle.com> wrote:

    Daniil,
    
    Looks good to me.
    
    If there are any management jtreg tests, I’d run these since your changes to OperatingSystemMXBean will 
    alter the behavior of these methods even for Linux hosts since cgroups is typically enabled causing the
    container detection to report containerized.
    
    It’s too bad getCpuLoad can’t detect that the cpuset is identical to the hosts in order to allow you to fallback to
    getSystemCpuLoad0. 
    
    
    Bob.
    
    
    > On Dec 3, 2019, at 2:42 PM, Daniil Titov <daniil.x.titov at oracle.com> wrote:
    > 
    > Please review the change that makes OperatingSystemMXBean methods return container specific information
    > rather than the host based data.
    > 
    > The webrev [1] is based on the code Andrew and Severin initially provided with some additional changes and combined
    > with the spec update David made [3].
    > 
    > The webrev corrects the implementation for the free/total swap methods as Bob noted to subtract the total
    > and free memory from the returned values.
    > 
    > It also corrects getCpuLoad() implementation, as Bob advised, to cover the case when CPU quotas are not active.
    > 
    > The webrev also takes into account the case when java.security.AccessControlException exception is thrown
    > during the initialization of the container subsystem ( e.g.  when java.policy doesn’t grant "read" access to
    > "/proc/self/mountinfo" file).
    > 
    > CSR for the spec changes [3] is approved.
    > 
    > Testing: Mach5 tiers1, tiers2, tiers3, tier4, tier5 (including open/test/hotspot/jtreg/containers/docker),  and tier6 tests passed .
    > 
    > [1] Webrev:  http://cr.openjdk.java.net/~dtitov/8226575/webrev.02/ 
    > [2] Jira issue :https://bugs.openjdk.java.net/browse/JDK-8226575 
    > [3] CSR https://bugs.openjdk.java.net/browse/JDK-8228428 
    > 
    > Thank you,
    > -Daniil
    > 
    >