RFR (M): 8207266: ThreadMXBean::getThreadAllocatedBytes() can be quicker for self thread
Hohensee, Paul
hohensee at amazon.com
Thu Sep 19 00:36:26 UTC 2019
And I filed 8231211 for the same thing. :)
Yes, please handle it, because it will go faster since I don't have access to a fast machine (just my laptop).
Webrev here:
http://cr.openjdk.java.net/~phh/8231211/webrev.00/
Thanks,
On 9/18/19, 5:25 PM, "Daniel D. Daugherty" <daniel.daugherty at oracle.com> wrote:
I created this sub-task for you:
JDK-8231210 [BACKOUT] JDK-8207266
ThreadMXBean::getThreadAllocatedBytes() can be quicker for self thread
https://bugs.openjdk.java.net/browse/JDK-8231210
If you would prefer, I can handle this backout for you.
Dan
On 9/18/19 8:21 PM, Hohensee, Paul wrote:
> Never having done this before, is it
>
> hg backout -r <original commit id>
>
> ? Do I file a JBS issue for the reversion? Seems necessary.
>
> On 9/18/19, 5:18 PM, "Daniel D. Daugherty" <daniel.daugherty at oracle.com> wrote:
>
> % hg backout
>
> is the usual way to do this...
>
> Dan
>
>
> On 9/18/19 8:17 PM, Hohensee, Paul wrote:
> > Is there a tool that will generate a reversal patch?
> >
> > On 9/18/19, 5:14 PM, "Daniel D. Daugherty" <daniel.daugherty at oracle.com> wrote:
> >
> > > Shall I go with that, or reverse the original patch?
> >
> > I'm a bit worried about what else might show up since the
> > NSK monitoring tests were not run prior to this push.
> >
> > I vote for backing out the fix until proper testing has
> > been done (and at least the one problem fixed...)
> >
> > Dan
> >
> >
> > On 9/18/19 8:00 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;
> > > }
> > >
> > > Shall I go with that, or reverse the original patch?
> > >
> > > On 9/18/19, 4:48 PM, "serviceability-dev on behalf of Hohensee, Paul" <serviceability-dev-bounces at openjdk.java.net on behalf of hohensee at amazon.com> wrote:
> > >
> > > I'll take a look.
> > >
> > > On 9/18/19, 4:40 PM, "David Holmes" <david.holmes at oracle.com> wrote:
> > >
> > > Paul,
> > >
> > > Unfortunately this patch has broken the vmTestbase/nsk/monitoring tests:
> > >
> > > [2019-09-18T22:59:32,349Z]
> > > /scratch/mesos/jib-master/install/jdk-14+15-615/src.full/open/test/hotspot/jtreg/vmTestbase/nsk/monitoring/share/server/ServerThreadMXBeanNew.java:32:
> > > error: ServerThreadMXBeanNew is not abstract and does not override
> > > abstract method getCurrentThreadAllocatedBytes() in ThreadMXBean
> > >
> > > and possibly other issues as we are seeing hundreds of failures.
> > >
> > > David
> > >
> > > On 18/09/2019 8:50 am, David Holmes wrote:
> > > > On 18/09/2019 12:10 am, Hohensee, Paul wrote:
> > > >> Thanks, Serguei. :)
> > > >>
> > > >> David, are you ok with the patch?
> > > >
> > > > Yep, nothing further from me.
> > > >
> > > > David
> > > >
> > > >> Paul
> > > >>
> > > >> *From: *"serguei.spitsyn at oracle.com" <serguei.spitsyn at oracle.com>
> > > >> *Date: *Tuesday, September 17, 2019 at 2:26 AM
> > > >> *To: *"Hohensee, Paul" <hohensee at amazon.com>, David Holmes
> > > >> <david.holmes at oracle.com>, Mandy Chung <mandy.chung at oracle.com>
> > > >> *Cc: *OpenJDK Serviceability <serviceability-dev at openjdk.java.net>,
> > > >> "hotspot-gc-dev at openjdk.java.net" <hotspot-gc-dev at openjdk.java.net>
> > > >> *Subject: *Re: RFR (M): 8207266:
> > > >> ThreadMXBean::getThreadAllocatedBytes() can be quicker for self thread
> > > >>
> > > >> Hi Paul,
> > > >>
> > > >> Thank you for refactoring and fixing the test.
> > > >> It looks great now!
> > > >>
> > > >> Thanks,
> > > >> Serguei
> > > >>
> > > >>
> > > >> On 9/15/19 02:52, Hohensee, Paul wrote:
> > > >>
> > > >> Hi, Serguei, thanks for the review. New webrev at
> > > >>
> > > >> http://cr.openjdk.java.net/~phh/8207266/webrev.09/
> > > >>
> > > >> I refactored the test’s main() method, and you’re correct,
> > > >> getThreadAllocatedBytes should be getCurrentThreadAllocatedBytes in
> > > >> that context: fixed.
> > > >>
> > > >> Paul
> > > >>
> > > >> *From: *"serguei.spitsyn at oracle.com"
> > > >> <mailto:serguei.spitsyn at oracle.com> <serguei.spitsyn at oracle.com>
> > > >> <mailto:serguei.spitsyn at oracle.com>
> > > >> *Organization: *Oracle Corporation
> > > >> *Date: *Friday, September 13, 2019 at 5:50 PM
> > > >> *To: *"Hohensee, Paul" <hohensee at amazon.com>
> > > >> <mailto:hohensee at amazon.com>, David Holmes <david.holmes at oracle.com>
> > > >> <mailto:david.holmes at oracle.com>, Mandy Chung
> > > >> <mandy.chung at oracle.com> <mailto:mandy.chung at oracle.com>
> > > >> *Cc: *OpenJDK Serviceability <serviceability-dev at openjdk.java.net>
> > > >> <mailto:serviceability-dev at openjdk.java.net>,
> > > >> "hotspot-gc-dev at openjdk.java.net"
> > > >> <mailto:hotspot-gc-dev at openjdk.java.net>
> > > >> <hotspot-gc-dev at openjdk.java.net>
> > > >> <mailto:hotspot-gc-dev at openjdk.java.net>
> > > >> *Subject: *Re: RFR (M): 8207266:
> > > >> ThreadMXBean::getThreadAllocatedBytes() can be quicker for self
> > > >> thread
> > > >>
> > > >> Hi Paul,
> > > >>
> > > >> It looks pretty good in general.
> > > >>
> > > >>
> > > >> http://cr.openjdk.java.net/~phh/8207266/webrev.08/test/jdk/com/sun/management/ThreadMXBean/ThreadAllocatedMemory.java.frames.html
> > > >>
> > > >>
> > > >> It would be nice to refactor the java main() method as it becomes
> > > >> too big.
> > > >> Two ways ofgetCurrentThreadAllocatedBytes() testing are good
> > > >> candidates
> > > >> to become separate methods.
> > > >>
> > > >> 98 long size1 = mbean.getThreadAllocatedBytes(id);
> > > >>
> > > >> Just wanted to double check if you wanted to invoke
> > > >> the getCurrentThreadAllocatedBytes() instead as it is
> > > >> a part of:
> > > >>
> > > >> 85 // First way, getCurrentThreadAllocatedBytes
> > > >>
> > > >>
> > > >> Thanks,
> > > >> Serguei
> > > >>
> > > >> On 9/13/19 12:11 PM, Hohensee, Paul wrote:
> > > >>
> > > >> Hi David, thanks for your comments. New webrev in
> > > >>
> > > >>
> > > >> http://cr.openjdk.java.net/~phh/8207266/webrev.08/
> > > >>
> > > >>
> > > >> Both the old and new versions of the code check that thread
> > > >> allocated memory is both supported and enabled. The existing version
> > > >> of getThreadAllocatedBytes(long []) calls
> > > >> verifyThreadAllocatedMemory(long []), which checks inline to make sure
> > > >> thread allocated memory is supported, then calls
> > > >> isThreadAllocatedMemoryEnabled() to verify that it's enabled.
> > > >> isThreadAllocatedMemoryEnabled() duplicates (!) the support check and
> > > >> returns the enabled flag. I removed the redundant check in the new
> > > >> version.
> > > >>
> > > >>
> > > >> You're of course correct about the back-to-back check.
> > > >> Application code can't know when the runtime will hijack a thread for
> > > >> its own purposes. I've removed the check.
> > > >>
> > > >>
> > > >> Paul
> > > >>
> > > >>
> > > >> On 9/13/19, 12:50 AM, "David Holmes"<david.holmes at oracle.com>
> > > >> <mailto:david.holmes at oracle.com> wrote:
> > > >>
> > > >>
> > > >> Hi Paul,
> > > >>
> > > >>
> > > >> On 13/09/2019 10:29 am, Hohensee, Paul wrote:
> > > >>
> > > >> > Thanks for clarifying the review rules. Would someone
> > > >> from the
> > > >>
> > > >> > serviceability team please review? New webrev at
> > > >>
> > > >> >
> > > >>
> > > >> >http://cr.openjdk.java.net/~phh/8207266/webrev.07/
> > > >>
> > > >>
> > > >> One aspect of the functional change needs clarification
> > > >> for me - and
> > > >>
> > > >> apologies if this has been covered in the past. It seems
> > > >> to me that
> > > >>
> > > >> currently we only check isThreadAllocatedMemorySupported
> > > >> for these
> > > >>
> > > >> operations, but if I read things correctly the updated
> > > >> code additionally
> > > >>
> > > >> checks isThreadAllocatedMemoryEnabled, which is a
> > > >> behaviour change not
> > > >>
> > > >> mentioned in the CSR.
> > > >>
> > > >>
> > > >> > I didn’t disturb the existing checks in the test, just
> > > >> added code to
> > > >>
> > > >> > check the result of getThreadAllocatedBytes(long) on a
> > > >> non-current
> > > >>
> > > >> > thread, plus the back-to-back no-allocation checks. The
> > > >> former wasn’t
> > > >>
> > > >> > needed before because getThreadAllocatedBytes(long) was
> > > >> just a wrapper
> > > >>
> > > >> > around getThreadAllocatedBytes(long []). This patch
> > > >> changes that, so I
> > > >>
> > > >> > added a separate test. The latter is supposed to fail
> > > >> if there’s object
> > > >>
> > > >> > allocation on calls to getCurrentThreadAllocatedBytes and
> > > >>
> > > >> > getThreadAllocatedBytes(long). I.e., a feature, not a
> > > >> bug, because
> > > >>
> > > >> > accumulation of transient small objects can be a
> > > >> performance problem.
> > > >>
> > > >> > Thanks to your review, I noticed that the back-to-back
> > > >> check on the
> > > >>
> > > >> > current thread was using getThreadAllocatedBytes(long)
> > > >> instead of
> > > >>
> > > >> > getCurrentThreadAllocatedBytes and fixed it. I also
> > > >> removed all
> > > >>
> > > >> > instances of “TEST FAILED: “.
> > > >>
> > > >>
> > > >> The back-to-back check is not valid in general. You don't
> > > >> know if the
> > > >>
> > > >> first check might trigger some class loading on the
> > > >> return path after it
> > > >>
> > > >> has obtained the first memory value. The check might also
> > > >> fail if using
> > > >>
> > > >> JVMCI and some compilation related activity occurs in the
> > > >> current thread
> > > >>
> > > >> on the second call. Also with the introduction of
> > > >> handshakes its
> > > >>
> > > >> possible the current thread might hit a safepoint checks
> > > >> that results in
> > > >>
> > > >> it executing a handshake operation that performs
> > > >> allocation. Potentially
> > > >>
> > > >> there could be numerous non-deterministic actions that
> > > >> might occur
> > > >>
> > > >> leading to unanticipated allocation.
> > > >>
> > > >>
> > > >> I understand what you want to test here, I just don't
> > > >> think it is
> > > >>
> > > >> reliably doable.
> > > >>
> > > >>
> > > >> Thanks,
> > > >>
> > > >> David
> > > >>
> > > >> -----
> > > >>
> > > >>
> > > >> >
> > > >>
> > > >> > Paul
> > > >>
> > > >> >
> > > >>
> > > >> > *From: *Mandy Chung<mandy.chung at oracle.com>
> > > >> <mailto:mandy.chung at oracle.com>
> > > >>
> > > >> > *Date: *Thursday, September 12, 2019 at 10:09 AM
> > > >>
> > > >> > *To: *"Hohensee, Paul"<hohensee at amazon.com>
> > > >> <mailto:hohensee at amazon.com>
> > > >>
> > > >> > *Cc: *OpenJDK
> > > >> Serviceability<serviceability-dev at openjdk.java.net>
> > > >> <mailto:serviceability-dev at openjdk.java.net>,
> > > >>
> > > >> >"hotspot-gc-dev at openjdk.java.net"
> > > >> <mailto:hotspot-gc-dev at openjdk.java.net>
> > > >> <hotspot-gc-dev at openjdk.java.net>
> > > >> <mailto:hotspot-gc-dev at openjdk.java.net>
> > > >>
> > > >> > *Subject: *Re: RFR (M): 8207266:
> > > >> ThreadMXBean::getThreadAllocatedBytes()
> > > >>
> > > >> > can be quicker for self thread
> > > >>
> > > >> >
> > > >>
> > > >> > On 9/3/19 12:38 PM, Hohensee, Paul wrote:
> > > >>
> > > >> >
> > > >>
> > > >> > Minor update in new
> > > >> webrevhttp://cr.openjdk.java.net/~phh/8207266/webrev.05/.
> > > >>
> > > >> >
> > > >>
> > > >> >
> > > >>
> > > >> > I only reviewed the library side implementation that
> > > >> looks good. I
> > > >>
> > > >> > expect the serviceability team to review the test and
> > > >> hotspot change.
> > > >>
> > > >> >
> > > >>
> > > >> >
> > > >>
> > > >> > Need a confirmatory review to push this. If I
> > > >> understand the rules correctly, it doesn't need a Reviewer review
> > > >> since Mandy's already reviewed it, it just needs a Committer review.
> > > >>
> > > >> >
> > > >>
> > > >> >
> > > >>
> > > >> > You need another reviewer to advice the following
> > > >> because I was not
> > > >>
> > > >> > close to the ThreadsList work.
> > > >>
> > > >> >
> > > >>
> > > >> > 2087 ThreadsListHandle tlh;
> > > >>
> > > >> >
> > > >>
> > > >> > 2088 JavaThread* java_thread =
> > > >> tlh.list()->find_JavaThread_from_java_tid(thread_id);
> > > >>
> > > >> >
> > > >>
> > > >> > 2089
> > > >>
> > > >> >
> > > >>
> > > >> > 2090 if (java_thread != NULL) {
> > > >>
> > > >> >
> > > >>
> > > >> > 2091 return java_thread->cooked_allocated_bytes();
> > > >>
> > > >> >
> > > >>
> > > >> > 2092 }
> > > >>
> > > >> >
> > > >>
> > > >> > This looks right to me.
> > > >>
> > > >> >
> > > >>
> > > >> >
> > > >> test/jdk/com/sun/management/ThreadMXBean/ThreadAllocatedMemory.java
> > > >>
> > > >> >
> > > >>
> > > >> > - "ThreadAllocatedMemory is expected to
> > > >> be disabled");
> > > >>
> > > >> >
> > > >>
> > > >> > + "TEST FAILED: ThreadAllocatedMemory is
> > > >> expected to be
> > > >>
> > > >> > disabled");
> > > >>
> > > >> >
> > > >>
> > > >> > Prepending "TEST FAILED" in exception message (in
> > > >> several places)
> > > >>
> > > >> >
> > > >>
> > > >> > seems redundant since such RuntimeException is thrown
> > > >> and expected
> > > >>
> > > >> >
> > > >>
> > > >> > a test failure.
> > > >>
> > > >> >
> > > >>
> > > >> > + // back-to-back calls shouldn't allocate any
> > > >> memory
> > > >>
> > > >> >
> > > >>
> > > >> > + size = mbean.getThreadAllocatedBytes(id);
> > > >>
> > > >> >
> > > >>
> > > >> > + size1 = mbean.getThreadAllocatedBytes(id);
> > > >>
> > > >> >
> > > >>
> > > >> > + if (size1 != size) {
> > > >>
> > > >> >
> > > >>
> > > >> > Is there anything in the test can do to help guarantee
> > > >> this? I didn't
> > > >>
> > > >> >
> > > >>
> > > >> > closely review this test. The main thing I advice is
> > > >> to improve
> > > >>
> > > >> >
> > > >>
> > > >> > the reliability of this test. Put it in another way,
> > > >> we want to
> > > >>
> > > >> >
> > > >>
> > > >> > ensure that this test change will pass all the time in
> > > >> various
> > > >>
> > > >> >
> > > >>
> > > >> > test configuration.
> > > >>
> > > >> >
> > > >>
> > > >> > Mandy
> > > >>
> > > >> >
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > >
> > >
> > >
> > >
> >
> >
> >
>
>
>
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