RFR (M): 8231209: [REDO] ThreadMXBean::getThreadAllocatedBytes() can be quicker for self thread
Mandy Chung
mandy.chung at oracle.com
Tue Sep 24 03:39:41 UTC 2019
Good question.
When HS express (mix-n-matched JDK and HS version) was supported, the
JMM_VERSION was rev'ed to enable the version checking. HS express is no
longer supported. JDK is supported to run with this version of HotSpot
VM. OTOH, this adds a new function in the middle of the function
table. I think it's a good convention to follow and bump the version
number.
Mandy
On 9/23/19 7:54 PM, Daniil Titov wrote:
> Hi Paul,
>
> I have a question about JMM_VERSION. Since the changeset introduces a new method in the interface
> should not JMM_VERSION declared in src/hotspot/share/include/jmm.h be bumped?
>
> Thank you,
> --Daniil
>
> On 9/23/19, 5:43 PM, "serviceability-dev on behalf of Hohensee, Paul" <serviceability-dev-bounces at openjdk.java.net on behalf of hohensee at amazon.com> wrote:
>
> Update:
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8231209
> CSR: https://bugs.openjdk.java.net/browse/JDK-8231374
> Webrev: http://cr.openjdk.java.net/~phh/8231209/webrev.01/
>
> All test suites that reference getThreadAllocatedBytes pass. These are
>
> hotspot/jtreg/vmTestbase/nsk/monitoring (contained the failing test)
> jdk/com/sun/management
> jdk/jdk/jfr/event/runtime
>
> Per Mandy, the default getCurrentThreadAllocatedBytes implementation throws a UOE.
>
> The CSR is a copy of the original, and in addition points out that ThreadMXBean is a PlatformManagedObject, why that's important, and why a default getCurrentThreadAllocatedBytes implementation is necessary.
>
> I changed the nsk test to make sure that the approach it uses will work with getCurrentThreadAllocatedBytes, which per Mandy is defined as a property. Though I'm happy to remove it if there's a consensus it isn't needed.
>
> Thanks,
>
> Paul
>
> On 9/19/19, 11:03 PM, "serguei.spitsyn at oracle.com" <serguei.spitsyn at oracle.com> wrote:
>
> Hi Paul,
>
> I have almost the same comments as David:
> - the same two spots of changes identified
> - the addition of the default method was expected
> - the change in test is a surprise (I also doubt, it is really needed)
> - new CSR is needed
>
>
> Sorry, I forgot to remind about running the vmTestbase monitoring tests. :(
>
> Thanks,
> Serguei
>
>
> On 9/19/19 16:06, David Holmes wrote:
> > Hi Paul,
> >
> > On 20/09/2019 2:52 am, Hohensee, Paul wrote:
> >> More formally,
> >>
> >> Bug: https://bugs.openjdk.java.net/browse/JDK-8231209
> >> Webrev: http://cr.openjdk.java.net/~phh/8231209/webrev.00/
> >
> > I'm assuming there are only two changes here:
> >
> > 1. The new method is now a default method that throws UOE.
> >
> > That seems fine.
> >
> > 2. You implemented the new method in the test class.
> >
> > I don't understand why you did that. The test can't be calling the new
> > method. Now that it is a default method we will get past the
> > compilation failure that caused the problem. So no change to the test
> > should be needed AFAICS.
> >
> > A new CSR request is needed. Just copy everything across from the old,
> > with the updated spec. But please also mention this is a
> > PlatformManagedObject in the compatibility discussion.
> >
> > Thanks,
> > David
> >
> >> Thanks,
> >>
> >> On 9/19/19, 9:44 AM, "serviceability-dev on behalf of Hohensee,
> >> Paul" <serviceability-dev-bounces at openjdk.java.net on behalf of
> >> hohensee at amazon.com> wrote:
> >>
> >> Off by 2 error. Changed the subject to reflect 8231209.
> >> http://cr.openjdk.java.net/~phh/8231209/webrev.00/
> >> Paul
> >> On 9/19/19, 6:31 AM, "Daniel D. Daugherty"
> >> <daniel.daugherty at oracle.com> wrote:
> >> > http://cr.openjdk.java.net/~phh/8231211/webrev.00/
> >> The redo bug is 8231209. 8231211 is closed as a dup
> >> of 8231210.
> >> Dan
> >> On 9/19/19 9:17 AM, Hohensee, Paul wrote:
> >> > I'll have the default method throw UOE. That's the same as
> >> the other default methods do.
> >> >
> >> > The necessary test fix is in
> >> test/hotspot/jtreg/vmTestbase/nsk/monitoring/share/server/ServerThreadMXBeanNew.java,
> >> which needs a new getCurrentThreadAllocatedBytes method, defined as
> >> >
> >> > public long getCurrentThreadAllocatedBytes() {
> >> > return (Long)
> >> invokeMethod("getCurrentThreadAllocatedBytes",
> >> > new Object[] { },
> >> > new String[] { });
> >> > }
> >> >
> >> > With this fix, the 134 tests in
> >> test/hotspot/jtreg/vmTestbase/nsk/monitoring/ThreadMXBean pass.
> >> Preliminary webrev at
> >> >
> >> > http://cr.openjdk.java.net/~phh/8231211/webrev.00/
> >> >
> >> > Is it worth adding getCurrentThreadAllocatedBytes tests to
> >> the
> >> test/hotspot/jtreg/vmTestbase/nsk/monitoring/ThreadMXBean/GetThreadAllocatedBytes
> >> set?
> >> >
> >> > Paul
> >> >
> >> > On 9/18/19, 8:16 PM, "David Holmes"
> >> <david.holmes at oracle.com> wrote:
> >> >
> >> > On 19/09/2019 12:57 pm, Mandy Chung wrote:
> >> > > On 9/18/19 5:00 PM, Hohensee, Paul wrote:
> >> > >> They all implement
> >> com.sun.management.ThreadMXBean, so adding a
> >> > >> getCurrentThreadAllocatedBytes broke them.
> >> Potential fix is to give it
> >> > >> a default implementation, vis
> >> > >>
> >> > >> public default long
> >> getCurrentThreadAllocatedBytes() {
> >> > >> return -1;
> >> > >> }
> >> > >>
> >> > >
> >> > > com.sun.management.ThreadMXBean (and other platform
> >> MXBeans) is a
> >> > > "sealed" interface which should only be implemented
> >> by JDK.
> >> >
> >> > Didn't realize that. I don't recall knowing about
> >> PlatformManagedObject.
> >> > Sealed types will at least allow this to be enforced,
> >> though I have to
> >> > wonder what the tests are doing here.
> >> >
> >> > > Unfortunately we don't have the sealed type feature
> >> yet. Yes it needs
> >> > > to be a default method. I think it should throw UOE.
> >> > >
> >> > > * @implSpec
> >> > > * The default implementation throws {@code
> >> > > UnsupportedOperationException}.
> >> > >
> >> > > The @throw UOE can make it clear that it does not
> >> support current thread
> >> > > memory allocation measurement.
> >> >
> >> > Yes that seems a reasonable default if we don't want
> >> this to be
> >> > implemented outside the platform.
> >> >
> >> > Thanks,
> >> > David
> >> >
> >> > > Mandy
> >> >
> >> >
> >>
>
>
>
>
>
>
>
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