+1
On 12/6/19 5:59 AM, Bob Vandette wrote:
On Dec 6, 2019, at 2:49 AM, David Holmes <david.hol...@oracle.com> wrote:
Hi Daniil,
I'm not familiar with all the details of the various API's involved here so
just a few general comments in places. I do have one major issue flagged below.
---
src/jdk.management/linux/native/libmanagement_ext/UnixOperatingSystem.c
! static int initialized=1;
Am I reading this right that the code currently fails to actually do the
initialization because of this ???
Style nit: if(perfInit()
space after "if"
---
src/jdk.management/share/classes/com/sun/management/OperatingSystemMXBean.java
The changes to allow for a return of -1 are somewhat more extensive than we
have previously discussed. These methods previously were (per the spec)
guaranteed to return some (assumably) meaningful value but now they are
effectively allowed to fail by returning -1. No existing code is expecting to
have to handle a return of -1 so I see this as a significant compatibility
issue. Surely there must always be some information available from the
operating environment? I see from the impl file:
// the host data, value 0 indicates that something went wrong while the
metric was read and
// in this case we return "information unavailable" code -1.
I don't agree with this. If the container metrics are messed up somehow we
should either fallback to the host value or else abort with some kind of
exception. Returning -1 is not an option here IMO.
I agree with David on the compatibility concern. I originally thought that -1
was already a specified return for all of these methods.
Since the 0 return failure from the Metrics API should only occur if one of the
cgroup subsystems is not enabled while others
are, I’d suggest we keep Daniil’s original logic to fall back to the host value
since a disabled subsystem is equivalent to no
limits.
Bob.
---
src/jdk.management/unix/classes/com/sun/management/internal/OperatingSystemImpl.java
src/jdk.management/windows/classes/com/sun/management/internal/OperatingSystemImpl.java
Can you please rename the legacy methods so that, for example,
getTotalMemorySize() calls getTotalMemorySize0() rather than
getTotalPhysicalMemorySize0(). That way we relegate the legacy names to the
interface only.
---
test/hotspot/jtreg/containers/docker/CheckOperatingSystemMXBean.java
System.out.println(String.format(...)
Why not simply
System.out.printf(..)
?
---
Thanks,
David
-----
On 6/12/2019 11:03 am, Daniil Titov wrote:
Hi Mandy and Bob,
Thank you for your comments. Please review a new version of the fix [1] that
makes
OperatingSystemImpl methods return -1 if one of the metric has value 0.
As Mandy recommended I also updated the Javadoc for OperatingSystemMXBean
indicating that methods could return -1 if the information is not available.
There were no changes in CSR [3] yet, I plan to proceed with them after the fix
is
reviewed.
In
http://cr.openjdk.java.net/~dtitov/8226575/webrev.03/src/java.base/linux/classes/jdk/internal/platform/cgroupv1/SubSystem.java.sdiff.html
Shouldn’t you keep the IOException catch clauses in case the file is not found?
There is no need in keeping IOException catch in these 2 places where it used
to be (getLongValueMatchingLine and getLongEntry methods).
As I understand IOException catch was required only because File.lines() and
File. readAllLines() can throw IOException.
Now these calls are performed inside
AccessController.doPrivileged(PrivilegedExceptionAction) that wraps
all checked exceptions in PrivilegedActionException that we are catching
now instead of IOException.
Here is the sampe of the stacktrace:
java.security.PrivilegedActionException: java.io.FileNotFoundException
at
java.base/java.security.AccessController.doPrivileged(AccessController.java:558)
at
java.base/jdk.internal.platform.cgroupv1.SubSystem.getLongValueMatchingLine(SubSystem.java:113)
at
java.base/jdk.internal.platform.cgroupv1.Metrics.getMemoryLimit(Metrics.java:390)
at
jdk.management/com.sun.management.internal.OperatingSystemImpl.getTotalMemorySize(OperatingSystemImpl.java:109)
at CheckOperatingSystemMXBean.main(CheckOperatingSystemMXBean.java:36)
Caused by: java.io.FileNotFoundException
at
java.base/jdk.internal.platform.cgroupv1.SubSystem.lambda$getLongValueMatchingLine$1(SubSystem.java:116)
at
java.base/java.security.AccessController.doPrivileged(AccessController.java:554)
In getStringValue method the whole code block is now executed inside
AccessController.doPrivileged() so we still need either catch
IOException inside this code block or convert this block to
PrivilegedExceptionAction and then put AccessController.doPrivileged
call inside new try/catch Block to catch PrivilegedExceptionAction. The former
approach looked more preferable.
Testing: Mach5 tier1-tier3 and open/test/hotspot/jtreg/containers/docker tests
passed. Tier4-tier6 tests are still running.
[1] Webrev: http://cr.openjdk.java.net/~dtitov/8226575/webrev.04/
[2] Jira issue: https://bugs.openjdk.java.net/browse/JDK-8226575
[3] CSR: https://bugs.openjdk.java.net/browse/JDK-8228428
Thanks,
Daniil
On 12/5/19, 12:59 PM, "Mandy Chung" <mandy.ch...@oracle.com> wrote:
On 12/5/19 12:50 PM, Bob Vandette wrote:
>
>>>> 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.
> Sorry, I didn’t respond to this. Since the calculation required for
getFreeSwapSpaceSize requires retries
> due to the access of multiple changing values, I think it’s best to
leave things as they are so the caller of
> these methods understands the limitations of the API.
OK with me.
> Also, the fact that swap size metrics include memory sizes is fully
documented in both the cgroup and docker
> online documentation so it’s probably best to be consistent.
>
>>>> 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.
> That is true but shouldn’t you return -1 in that case?
>
> I originally thought it was ok to fall back to the host data for 0
values but I think its better to return unavailable (-1)
> I think you might want to change all >= 0 to > 0 and return -1 if any of
the values are 0. This would be more consistent.
+1
The javadoc should be changed and returns -1 when it's unavailable and
the CSR should also be updated to reflect this. I'm sure Joe can
re-approve the CSR quickly when the fix is reviewed and approved.
> You should only fall back to the original logic (host values) if
container values are set to unlimited.
>
+1
Mandy
