Hi Mandy and Bob,
Please review a new version of the webrev that addresses the most of these
issues:
1) The interface and spec [3] were updated to use default methods. CSR [3] was
re-approved.
2) Security-sensitive operations in j.i.p.cgroupv1.Metrics and in
j.i.p.cgroupv1. SubSystem
were wrapped with doPrivileged
3) getCpuLoad () method was optimized to fallback to getSystemCpuLoad0 if the
cpuset is identical to the host's one.
It uses sysconf(_SC_NPROCESSORS_CONF) to retrieve the number of CPUs
configured on the host . Testing with
different --cpuset-cpus settings inside a Docker container proved that it
always returns the same number of hosts configured
CPUs regardless of --cpuset-cpus settings while the same settings affect
getEffectiveCpuSetCpus and getCpuSetCpus() metrics.
In addition, getCpuLoad () method now returns -1 in the cases when quotas
are active but cpu usage and cpu period metrics are not available and
in the case when for some reason it fails to retrieve a valid CPU load for
one of CPUs while iteration over them
>> CheckOperatingSystemMXBean.java
>> System.out.println(String.format(...)) can simply be replaced with
>> System.out.format.
I had to leave it unchanged since replacing it with System.out.format results
in the tests instability as it makes the trace output
occasionally Intervene here (the trace message sometimes is printed inside
this message) and tests cannot find the expected
pattern in the output.
>> It may worth considering adding Metrics::getSwapLimit and
>> Metrics::getSwapUsage and move the computation to the implementation of
>> Metrics. Bob may have an opinion.
There was no any new input regarding this so I decided to leave it unchanged.
>>Also it seems correct for the memory related methods to check if
>>(containerMetrics != null && containerMetrics.getMemoryLimit() >= 0).
>> BTW what does it mean if limit == 0?
Per Docker docs the minimum allowed value for memory limit (--memory option)
is 4 megabytes.
And if memory limit is unset the return value is -1. Thus, in my understanding
the value 0 is only possible
if something went wrong while retrieving this metric.
Testing: Mach5 tier1-tier6 tests (that include
open/test/hotspot/jtreg/containers/docker and : jdk_management tests) passed.
[1] Webrev: http://cr.openjdk.java.net/~dtitov/8226575/webrev.03/
[2] Jira issue: https://bugs.openjdk.java.net/browse/JDK-8226575
[3] CSR: https://bugs.openjdk.java.net/browse/JDK-8228428
Thank you,
Daniil
On 12/4/19, 4:09 PM, "Mandy Chung" <[email protected]> wrote:
On 12/3/19 9:40 PM, Daniil Titov wrote:
>
>>> Under what circumstance that limit or memLimit is < 0?
> The memory limit metrics is not available if JVM runs on Linux host ( not
in a docker container) or if a docker container was started without
> specifying a memory limit ( without '--memory=' Docker option) . In
latter there is no limit on how much memory the container can use and
> it can use as much memory as the host's OS allows.
>
OK. Please add a comment to the code.
It may worth considering adding Metrics::getSwapLimit and
Metrics::getSwapUsage and move the computation to the implementation of
Metrics. Bob may have an opinion.
Also it seems correct for the memory related methods to check if
(containerMetrics != null && containerMetrics.getMemoryLimit() >= 0).
BTW what does it mean if limit == 0?
>>> Is it worth specifying this case?
> I believe yes, since it covers the cases when JVM runs on a Linux host
or a docker container was started without memory limitation.
>
I was wondering if the javadoc should specify that.
>>> It fallbacks to return the system's total swap space size - this is not
really what it should report.
> For the case when JVM runs on a Linux host it is exactly what we want.
The only problematic case is if JVM runs inside a docker container without a
memory limit set.
> However, I am not sure how we could differentiate these 2 cases.
As this is the case when the limit is not set in the container, it
returns the system metrics which sounds appropriate.
>
>>> Similarly, getFreeMemorySize and getTotalMemorySize and getCpuLoad.
> For getTotalMemorySize I think we are good here. If limit is not set
then all memory the host's OS have is available.
> For getFreeMemorySize the problematic case is if is the memory limit is
set but the memory usage for some reason is not available
(containerMetrics.getMemoryUsage() returns 0).
Will zero memory usage happen?
> Probably in this case we should just return -1 as currently
getFreePhysicalMemorySize0() does if it cannot retrieve a valid result.
>
> For getCpuLoad() the problematic case if CPU quotas are active but
CpuPeriod, CpuNumPeriods , or getCpuUsage are unavailable or if a valid CPU
load for some CPU was
> not retrieved, or if all retrieved CPU load values happen to be zeros.
Probably we should just return -1 in these cases rather then falling back to
getSystemCpuLoad0()
>
returning -1 sounds right.
>>>
src/jdk.management/windows/classes/com/sun/management/internal/OperatingSystemImpl.java
>>> There is no strong need to make the deprecated methods as default
methods. If they were default methods, they only need to be implemented once
as opposed to in all OS-specific implementations.
> I could make these methods defaults if you feel it is a better approach
here.
>
>
It's not strictly needed but I can go either way.
>>> CheckOperatingSystemMXBean.java
>>> System.out.println(String.format(...)) can simply be replaced with
System.out.format.
> I will include this change in the next webrev, thank you!
>
>
thanks
Mandy
