jmx-dev committed > max in MemoryMXBean#getHeapMemoryUsage()

[Daniel Mitterdorfer]

Hi Alan,

to be honest, I was not sure either where to post it. I'll post it there
then, thanks.

Daniel

Am Do., 12. Juli 2018 um 15:12 Uhr schrieb Alan Bateman <
Alan.Bateman at oracle.com>:

> probably best to ask this on serviceability-dev as it's more about the
> java.lang.management implementation rather than JMX.
>
> On 12/07/2018 13:57, Daniel Mitterdorfer wrote:
> > Hi,
> >
> > while working on a change in Elasticsearch, I discovered an interesting
> > situation related to the implementation of jmm_getMemoryUsage (see
> > [jdk-mem-usage]). In one of the test runs, a test failed with the
> > following
> > exception:
> >
> > java.lang.IllegalArgumentException: committed = 542113792 should be <
> > max = 536870912
> > at java.lang.management.MemoryUsage.<init>(MemoryUsage.java:166)
> > at sun.management.MemoryImpl.getMemoryUsage0(Native Method)
> > at sun.management.MemoryImpl.getHeapMemoryUsage(MemoryImpl.java:71)
> > at
> >
> org.elasticsearch.indices.breaker.HierarchyCircuitBreakerService.currentMemoryUsage(HierarchyCircuitBreakerService.java:246)
> > [...]
> >
> > This happened on MacOS 10.12.6 with JDK 10 (build 10.0.1+10). The only
> > JVM flags
> > specified where -Xms512M -Xmx512M. So far this failure occurred only
> > once and I
> > could not reproduce it yet.
> >
> > The values reported in the exception message above are:
> >
> > * "max": 536870912 = 512MB (exactly)
> > * "committed": 542113792 = 517MB (exactly), i.e. 5MB more than "max".
> >
> > As the value of "max" is exactly what we have specified with -Xmx it
> > seems to
> > indicate that the problem is the calculation of "committed". I do not
> > understand under which conditions this can happen thus I post this to the
> > mailing list in case anybody has ideas what might cause this.
> >
> > I plan to run further tests with JVM trace logging enabled
> > (-Xlog:gc*=trace,heap*=trace,tlab*=off:stdout:time,pid,tid,level,tags
> > to be
> > precise) in the hope that this problem will occur again and I can
> > provide logs
> > that help to debug / fix the problem.
> >
> > Searching for that error message, there is [JDK-8020530] but that one
> > is about
> > *non-heap* memory usage and has already been resolved a while ago.
> Several
> > sources (e.g. [apache-ignite-workaround] or [netbeans-bug]) seem to
> > indicate
> > that this problem happened indeed in the wild but what I find odd is
> > that I
> > could not find a single ticket in the OpenJDK bug tracker or a
> > discussion on a
> > JDK mailing list about this problem.
> >
> > I'd be glad to get any pointers on what might cause this or requests for
> > additional info that I need to provide to help analyze this problem.
> >
> > Thanks,
> > Daniel
> >
> > [jdk-mem-usage]
> >
> http://hg.openjdk.java.net/jdk-updates/jdk10u/file/142f0ed9ff5b/src/hotspot/share/services/management.cpp#l728
> > [JDK-8020530] https://bugs.openjdk.java.net/browse/JDK-8020530
> > [apache-ignite-workaround]
> >
> https://github.com/apache/ignite/blob/df4fd65a32/modules/core/src/main/java/org/apache/ignite/internal/managers/discovery/GridDiscoveryManager.java#L336-L346
> > [netbeans-bug] https://netbeans.org/bugzilla/show_bug.cgi?id=194733
> >
>
>
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