RFR(L) 8153224 Monitor deflation prolong safepoints (CR14/v2.14/17-for-jdk15)
Carsten Varming
varming at gmail.com
Tue Jun 2 18:13:50 UTC 2020
Hi Dan,
I like the new comment. Thank you for doing the update.
Carsten
On Tue, Jun 2, 2020 at 1:54 PM Daniel D. Daugherty <
daniel.daugherty at oracle.com> wrote:
> Hi Carsten,
>
> See replies below...
>
> David, Erik and Robbin, if you folks could also check out the revised
> comment below that would be appreciated.
>
>
> On 6/2/20 9:39 AM, Carsten Varming wrote:
>
> Hi Dan,
>
> See inline.
>
> On Mon, Jun 1, 2020 at 11:32 PM Daniel D. Daugherty <
> daniel.daugherty at oracle.com> wrote:
>
>> Hi Carsten,
>>
>> Thanks for chiming in on this review thread!!
>>
>
> It is my pleasure. You know the code is solid when the discussion is
> focused on the comments.
>
>
> So true, so very true!
>
>
>
>
>> On 6/1/20 10:41 PM, Carsten Varming wrote:
>>
>> Hi Dan,
>>
>> I like the new protocol, but I had to think about how the extra increment
>> to _contentions replaced the check on _owner that I originally added.
>>
>>
>> Right. The check on _owner was described in detail in the OpenJDK wiki
>> subsection that was called "T-enter Wins By A-B-A". It can still be
>> found by going thru the wiki's history links.
>>
>> That subsection was renamed and rewritten and can be found here:
>>
>>
>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation#AsyncMonitorDeflation-T-enterWinsByCancellationViaDEFLATER_MARKERSwap
>>
>>
>> I am thinking that the increased _contention value is a little mark left
>> on the ObjectMonitor to signal to the deflater thread (which must be in the
>> middle of trying to acquire the object monitor as _owner was set to
>> DEFLATER_MARKER) that the deflater thread lost the race.
>>
>>
>> That is exactly what the extra increment is being used for.
>>
>> In my reply to David H. that you quoted below, I describe the progression
>> of contention values thru the two possible race scenarios. The progression
>> shows the T-enter thread winning the race and marking the contention field
>> with the extra increment while the T-deflater thread recognizes that it
>> has
>> lost the race and unmarks the contention field with an extra decrement.
>>
>
> I noticed that. Looks like David and I were racing and David won. :)
>
>
>> That little mark stays with the object monitor long after the thread is
>> done with the monitor.
>>
>>
>> The "little mark" stays with the ObjectMonitor after T-enter is done
>> entering until the T-deflater thread recognizes that the async deflation
>> was canceled and does an extra decrement. I don't think I would describe
>> it as "long after".
>>
>
> Sorry about the use of "long after". When I think about the correctness of
> protocols, like the deflation protocol, I end up thinking about sequences
> of instructions and the relevant interleavings. In that context I often end
> up using phrases like "long after" and "after" to mean anything after a
> particular instruction. I did not mean to imply anything about the relative
> speed of the execution of the code.
>
>
> It's okay. I do something similar in the transaction diagrams that
> I use to work out timing issues: <thread stalls> ... <thread resumes>
>
> The only point that I was trying to make is that the T-deflate thread
> is responsible for cleaning up the extra mark and it's committed to
> the code path that will result in the cleanup. Yes, there may be a
> <thread stalls> between the time that T-deflate recognizes that async
> deflation was canceled and when T-deflate does the extra decrement,
> but I don't see any harm in it.
>
>
>
>
>> It might be worth adding a comment to the code explaining that after the
>> increment, the _contention field can only be set to 0 by a corresponding
>> decrement in the async deflater thread, ensuring that the Atomic::cmpxchg(&mid->_contentions,
>> (jint)0, -max_jint) on line 2166 fails. In particular, the comment:
>>
>> +. // .... We bump contentions an+ // extra time to prevent the async deflater thread from temporarily+ // changing it to -max_jint and back to zero (no flicker to confuse+ // is_being_async_deflated()
>>
>> confused me as after the deflater thread sets _contentions to -max_jint,
>> the deflater thread has won the race and the object monitor is about to be
>> deflated.
>>
>>
>> For context, here's the code and comment being discussed:
>>
>> 527 if (AsyncDeflateIdleMonitors &&
>> 528 try_set_owner_from(DEFLATER_MARKER, Self) == DEFLATER_MARKER) { 529 // Cancelled the in-progress async deflation. We bump contentions an 530 // extra time to prevent the async deflater thread from temporarily 531 // changing it to -max_jint and back to zero (no flicker to confuse 532 // is_being_async_deflated()). The async deflater thread will 533 // decrement contentions after it recognizes that the async 534 // deflation was cancelled. 535 add_to_contentions(1);
>>
>>
>> This part of the new comment:
>>
>> 532 // ... The async deflater thread will
>> 533 // decrement contentions after it recognizes that the async
>> 534 // deflation was cancelled.
>>
>> makes it clear that the async deflater thread does the corresponding
>> decrement
>> to the increment done by the T-enter thread so that covers this part of
>> your
>> comment above:
>>
>> the _contention field can only be set to 0 by a corresponding
>> decrement
>> in the async deflater thread
>>
>> This part of the new comment:
>>
>> 529 // ... We bump contentions an
>> 530 // extra time to prevent the async deflater thread from
>> temporarily
>> 531 // changing it to -max_jint and back to zero (no flicker to
>> confuse
>> 532 // is_being_async_deflated()).
>>
>> makes it clear that we're keeping make-contentions-negative part of the
>> async deflation protocol from happening so that covers this part of your
>> comment above:
>>
>> ensuring that the Atomic::cmpxchg(&mid->_contentions, (jint)0,
>> -max_jint)
>> on line 2166 fails.
>>
>> This part of your comment above makes it clear where the confusion arises:
>>
>> confused me as after the deflater thread sets _contentions to
>> -max_jint,
>> the deflater thread has won the race and the object monitor is about
>> to
>> be deflated.
>>
>> Your original algorithm is a three-part async deflation protocol:
>>
>> Part 1 - set owner field to DEFLATER marker
>> Part 2 - make a zero contentions field -max_jint
>> Part 3 - check to see if the owner field is still DEFLATER_MARKER
>>
>> If part 3 fails, then the contentions field that is currently negative
>> has max_jint added to it to complete the bail out process. It's that
>> third part that makes the contentions field flicker from:
>>
>> 0 -> -max_jint -> 0
>>
>> And the extra contentions increment in the new two part protocol solves
>> that flicker and allows us to treat (contentions < 0) as a linearization
>> point.
>>
>> Please let me know if this clarifies your concern.
>>
>
> I am no longer confused, but the cause of my confusion is still present in
> the comment.
>
> This group knows about the three part algorithm, but when the code is
> pushed there is no representation of the three part algorithm in the code
> or repository.
>
>
> That's a really good point and a side effect of my living with this
> code for a very long time...
>
>
> I forgot the details of the algorithm and read the latest version of the
> code to figure out what the flickering was about. As you would expect, I
> found that there is no way the code can cause the flicker mentioned. That
> made me worried. I started to question myself: What can cause the behavior
> that is described in the comments? What am I missing? As a result, I think
> it is best if we keep the flickering to ourselves and update the comment to
> describe that because _owner was DEFLATER_MARKER the deflation thread must
> be in the middle of the protocol for deflating the object monitor, and in
> particular, incrementing _contentions ensures the failure of the final CAS
> in the deflation protocol (final in the protocol implemented in the code).
>
>
> The above is a more clear expression of your concerns and I agree.
>
>
> To be clear:
>
> > 529 // Cancelled the in-progress async deflation.
>
> I would expend this comment by mentioning that the deflator thread cannot
> win the last part of the 2-part deflation protocol as 0 < _contentions
> (pre-condition to this method).
>
> > We bump contentions an
> > 530 // extra time to prevent the async deflater thread from temporarily
> > 531 // changing it to -max_jint and back to zero (no flicker to confuse
> > 532 // is_being_async_deflated()).
>
> I would replace this part with something along the lines of: We bump
> contentions an extra time to prevent the deflator thread from winning the
> last part of the (2-part) deflation protocol after this thread decrements
> _contentions as part of the release of the object monitor.
>
> > The async deflater thread will
> > 533 // decrement contentions after it recognizes that the async
> > 534 // deflation was cancelled.
>
> I would keep this part.
>
>
> So here's my rewrite of the code and comment block:
>
> if (AsyncDeflateIdleMonitors &&
> try_set_owner_from(DEFLATER_MARKER, Self) == DEFLATER_MARKER) {
> // Cancelled the in-progress async deflation by changing owner from
> // DEFLATER_MARKER to Self. As part of the contended enter protocol,
> // contentions was incremented to a positive value before EnterI()
> // was called and that prevents the deflater thread from winning the
> // last part of the 2-part async deflation protocol. After EnterI()
> // returns to enter(), contentions is decremented because the caller
> // now owns the monitor. We bump contentions an extra time here to
> // prevent the deflater thread from winning the last part of the
> // 2-part async deflation protocol after the regular decrement
> // occurs in enter(). The deflater thread will decrement contentions
> // after it recognizes that the async deflation was cancelled.
> add_to_contentions(1);
>
> I've made this change to both places in EnterI() that had the original
> confusing comment.
>
> Please let me know if this rewrite works for everyone.
>
> Since I've already pushed 8153224, I'll file a new bug to push this
> clarification once we're all in agreement here.
>
> Dan
>
>
>
> I hope this helps,
> Carsten
>
> Otherwise, the code looks great. I am looking forward to seeing in the
>> repo.
>>
>>
>> Thanks! The code should be there soon.
>>
>> Dan
>>
>>
>>
>> Carsten
>>
>> On Mon, Jun 1, 2020 at 8:32 PM Daniel D. Daugherty <
>> daniel.daugherty at oracle.com> wrote:
>>
>>> Hi David,
>>>
>>> On 6/1/20 7:58 PM, David Holmes wrote:
>>> > Hi Dan,
>>> >
>>> > Sorry for the delay.
>>>
>>> No worries. It's always worth waiting for your code review in general
>>> and, with the complexity of this project, it's on my must-do list!
>>>
>>>
>>> >
>>> > On 28/05/2020 3:20 am, Daniel D. Daugherty wrote:
>>> >> Greetings,
>>> >>
>>> >> Erik O. had an idea for changing the three part async deflation
>>> protocol
>>> >> into a two part async deflation protocol where the second part
>>> (setting
>>> >> the contentions field to -max_jint) is a linearization point. I've
>>> taken
>>> >> Erik's proposal (which was relative to CR12/v2.12/15-for-jdk15),
>>> merged
>>> >> it with CR13/v2.13/16-for-jdk15, and made a few minor tweaks.
>>> >>
>>> >> I have attached the change list from CR13 to CR14 and I've also added
>>> a
>>> >> link to the CR13-to-CR14-changes file to the webrevs so it should be
>>> >> easy
>>> >> to find.
>>> >>
>>> >> Main bug URL:
>>> >>
>>> >> JDK-8153224 Monitor deflation prolong safepoints
>>> >> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>
>>> >> The project is currently baselined on jdk-15+24.
>>> >>
>>> >> Here's the full webrev URL for those folks that want to see all of the
>>> >> current Async Monitor Deflation code in one go (v2.14 full):
>>> >>
>>> >>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/17-for-jdk15+24.v2.14.full/
>>> >>
>>> >>
>>> >> Some folks might want to see just what has changed since the last
>>> review
>>> >> cycle so here's a webrev for that (v2.14 inc):
>>> >>
>>> >>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/17-for-jdk15+24.v2.14.inc/
>>> >
>>> >
>>> > src/hotspot/share/runtime/synchronizer.cpp
>>> >
>>> > I'm having a little trouble keeping the _contentions relationships in
>>> > my head. In particular with this change I can't quite grok the:
>>> >
>>> > // Deferred decrement for the JT EnterI() that cancelled the async
>>> > deflation.
>>> > mid->add_to_contentions(-1);
>>> >
>>> > change. I kind of get EnterI() does an extra increment and the
>>> > deflator thread does the above matching decrement. But given the two
>>> > changes can happen in any order I'm not sure what the possible visible
>>> > values for _contentions will be and how that might affect other code
>>> > inspecting it?
>>>
>>> I have a sub-section in the OpenJDK wiki dedicated to this particular
>>> race:
>>>
>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation#AsyncMonitorDeflation-T-enterWinsByCancellationViaDEFLATER_MARKERSwap
>>>
>>> In order for this race condition to manifest, the T-enter thread has to
>>> successfully swap the owner field's DEFLATER_MARKER value for Self. That
>>> swap will eventually cause the T-deflate thread to realize that the async
>>> deflation that it started has been canceled.
>>>
>>> The diagram shows the progression of contentions values:
>>>
>>> - ObjectMonitor box 1 shows contentions == 1 because T-enter incremented
>>> the contentions field
>>>
>>> - ObjectMonitor box 2 shows contentions == 2 because EnterI() did the
>>> extra increment.
>>>
>>> - ObjectMonitor box 3 shows contentions == 1 because T-enter did the
>>> regular contentions decrement.
>>>
>>> - ObjectMonitor box 4 shows contentions == 0 because T-deflate did the
>>> extra contentions decrement.
>>>
>>> Now it is possible for T-deflate to do the extra decrement before T-enter
>>> does the extra increment. If I were to add another diagram to show that
>>> variant of the race, that progression of contentions values would be:
>>>
>>> - ObjectMonitor box 1 shows contentions == 1 because T-enter incremented
>>> the contentions field
>>>
>>> - ObjectMonitor box 2 shows contentions == 0 because T-deflate did the
>>> extra contentions decrement.
>>>
>>> - ObjectMonitor box 3 shows contentions == 1 because EnterI() did the
>>> extra increment.
>>>
>>> - ObjectMonitor box 4 shows contentions == 0 because T-enter did the
>>> regular contentions decrement.
>>>
>>> Notice that in this second scenario the contentions field never goes
>>> negative so there's nothing to confuse a potential caller of
>>> is_being_async_deflated():
>>>
>>> inline bool ObjectMonitor::is_being_async_deflated() {
>>> return AsyncDeflateIdleMonitors && contentions() < 0;
>>> }
>>>
>>> It is not possible for T-deflate's extra decrement of the contentions
>>> field to make the contentions field negative. That decrement only happens
>>> when T-deflate detects that the async deflation has been canceled and
>>> async deflation can only be canceled after T-enter has already made the
>>> contentions field > 0.
>>>
>>> Please let me know if this resolves your concern about:
>>>
>>> > // Deferred decrement for the JT EnterI() that cancelled the async
>>> > deflation.
>>> > mid->add_to_contentions(-1);
>>>
>>> I'm not planning to update the OpenJDK wiki to add a second variant of
>>> the cancellation race. Please let me know if that is okay.
>>>
>>> >
>>> > But otherwise the changes in this version seem good and overall the
>>> > protocol seems simpler.
>>>
>>> This sounds like a thumbs up, but I'm looking for something more
>>> definitive.
>>>
>>>
>>> > I'm still going to spend some more time going over the complete webrev
>>> > to get a fuller sense of things.
>>>
>>> As always, if you find something after I've pushed, we'll deal with it.
>>>
>>> Thanks for your many re-reviews for this project!!
>>>
>>> Dan
>>>
>>>
>>> >
>>> > Thanks,
>>> > David
>>> >
>>> >>
>>> >>
>>> >> The OpenJDK wiki has been updated for v2.14.
>>> >>
>>> >> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>
>>> >> The jdk-15+24 based v2.14 version of the patch has gone thru Mach5
>>> >> Tier[1-5]
>>> >> testing with no related failures; Mach5 Tier[67] are running now and
>>> >> so far
>>> >> have no related failures. I'll kick off Mach5 Tier8 after the other
>>> >> tiers
>>> >> have finished since Mach5 is a bit busy right now.
>>> >>
>>> >> I'm also running my usual inflation stress testing on Linux-X64 and
>>> >> macOSX
>>> >> and so far there are no issues.
>>> >>
>>> >> Thanks, in advance, for any questions, comments or suggestions.
>>> >>
>>> >> Dan
>>> >>
>>> >>
>>> >> On 5/21/20 2:53 PM, Daniel D. Daugherty wrote:
>>> >>> Greetings,
>>> >>>
>>> >>> I have made changes to the Async Monitor Deflation code in response
>>> to
>>> >>> the CR12/v2.12/15-for-jdk15 code review cycle. Thanks to David H. and
>>> >>> Erik O. for their OpenJDK reviews in the v2.12 round!
>>> >>>
>>> >>> I have attached the change list from CR12 to CR13 and I've also
>>> added a
>>> >>> link to the CR12-to-CR13-changes file to the webrevs so it should be
>>> >>> easy
>>> >>> to find.
>>> >>>
>>> >>> Main bug URL:
>>> >>>
>>> >>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>
>>> >>> The project is currently baselined on jdk-15+24.
>>> >>>
>>> >>> Here's the full webrev URL for those folks that want to see all of
>>> the
>>> >>> current Async Monitor Deflation code in one go (v2.13 full):
>>> >>>
>>> >>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/16-for-jdk15%2b24.v2.13.full/
>>> >>>
>>> >>>
>>> >>> Some folks might want to see just what has changed since the last
>>> >>> review
>>> >>> cycle so here's a webrev for that (v2.13 inc):
>>> >>>
>>> >>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/16-for-jdk15%2b24.v2.13.inc/
>>> >>>
>>> >>>
>>> >>>
>>> >>> The OpenJDK wiki is currently at v2.13 and might require minor
>>> >>> tweaks for v2.12
>>> >>> and v2.13. Yes, I need to make yet another crawl thru review of it...
>>> >>>
>>> >>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>
>>> >>> The jdk-15+24 based v2.13 version of the patch is going thru the
>>> usual
>>> >>> Mach5 testing right now. It is also going thru my usual inflation
>>> >>> stress
>>> >>> testing on Linux-X64 and macOSX.
>>> >>>
>>> >>> Thanks, in advance, for any questions, comments or suggestions.
>>> >>>
>>> >>> Dan
>>> >>>
>>> >>> On 5/14/20 5:40 PM, Daniel D. Daugherty wrote:
>>> >>>> Greetings,
>>> >>>>
>>> >>>> I have made changes to the Async Monitor Deflation code in response
>>> to
>>> >>>> the CR11/v2.11/14-for-jdk15 code review cycle. Thanks to David H.,
>>> >>>> Erik O.,
>>> >>>> and Robbin for their OpenJDK reviews in the v2.11 round!
>>> >>>>
>>> >>>> I have attached the change list from CR11 to CR12 and I've also
>>> >>>> added a
>>> >>>> link to the CR11-to-CR12-changes file to the webrevs so it should
>>> >>>> be easy
>>> >>>> to find.
>>> >>>>
>>> >>>> Main bug URL:
>>> >>>>
>>> >>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>
>>> >>>> The project is currently baselined on jdk-15+23.
>>> >>>>
>>> >>>> Here's the full webrev URL for those folks that want to see all of
>>> the
>>> >>>> current Async Monitor Deflation code in one go (v2.12 full):
>>> >>>>
>>> >>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/15-for-jdk15%2b23.v2.12.full/
>>> >>>>
>>> >>>>
>>> >>>> Some folks might want to see just what has changed since the last
>>> >>>> review
>>> >>>> cycle so here's a webrev for that (v2.12 inc):
>>> >>>>
>>> >>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/15-for-jdk15%2b23.v2.12.inc/
>>> >>>>
>>> >>>>
>>> >>>>
>>> >>>> The OpenJDK wiki is currently at v2.11 and might require minor
>>> >>>> tweaks for v2.12:
>>> >>>>
>>> >>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>
>>> >>>> The jdk-15+23 based v2.12 version of the patch is going thru the
>>> usual
>>> >>>> Mach5 testing right now.
>>> >>>>
>>> >>>> Thanks, in advance, for any questions, comments or suggestions.
>>> >>>>
>>> >>>> Dan
>>> >>>>
>>> >>>>
>>> >>>> On 5/7/20 1:08 PM, Daniel D. Daugherty wrote:
>>> >>>>> Greetings,
>>> >>>>>
>>> >>>>> I have made changes to the Async Monitor Deflation code in
>>> >>>>> response to
>>> >>>>> the CR10/v2.10/13-for-jdk15 code review cycle and DaCapo-h2 perf
>>> >>>>> testing.
>>> >>>>> Thanks to Erik O., Robbin and David H. for their OpenJDK reviews
>>> >>>>> in the
>>> >>>>> v2.10 round! Thanks to Eric C. for his help in isolating the
>>> >>>>> DaCapo-h2
>>> >>>>> performance regression.
>>> >>>>>
>>> >>>>> With the removal of ref_counting and the ObjectMonitorHandle
>>> >>>>> class, the
>>> >>>>> Async Monitor Deflation project is now closer to Carsten's original
>>> >>>>> prototype. While ref_counting gave us ObjectMonitor* safety
>>> >>>>> enforced by
>>> >>>>> code, I saw a ~22.8% slow down with -XX:-AsyncDeflateIdleMonitors
>>> >>>>> ("off"
>>> >>>>> mode). The slow down with "on" mode -XX:+AsyncDeflateIdleMonitors
>>> >>>>> is ~17%.
>>> >>>>>
>>> >>>>> I have attached the change list from CR10 to CR11 instead of
>>> >>>>> putting it in
>>> >>>>> the body of this email. I've also added a link to the
>>> >>>>> CR10-to-CR11-changes
>>> >>>>> file to the webrevs so it should be easy to find.
>>> >>>>>
>>> >>>>> Main bug URL:
>>> >>>>>
>>> >>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>
>>> >>>>> The project is currently baselined on jdk-15+21.
>>> >>>>>
>>> >>>>> Here's the full webrev URL for those folks that want to see all of
>>> >>>>> the
>>> >>>>> current Async Monitor Deflation code in one go (v2.11 full):
>>> >>>>>
>>> >>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/14-for-jdk15%2b21.v2.11.full/
>>> >>>>>
>>> >>>>>
>>> >>>>> Some folks might want to see just what has changed since the last
>>> >>>>> review
>>> >>>>> cycle so here's a webrev for that (v2.11 inc):
>>> >>>>>
>>> >>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/14-for-jdk15%2b21.v2.11.inc/
>>> >>>>>
>>> >>>>>
>>> >>>>> Because of the removal of ref_counting and the ObjectMonitorHandle
>>> >>>>> class, the
>>> >>>>> incremental webrev is a bit noisier than I would have preferred.
>>> >>>>>
>>> >>>>>
>>> >>>>> The OpenJDK wiki has NOT YET been updated for this round of
>>> changes:
>>> >>>>>
>>> >>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>
>>> >>>>> The jdk-15+21 based v2.11 version of the patch has been thru Mach5
>>> >>>>> tier[1-6]
>>> >>>>> testing on Oracle's usual set of platforms. Mach5 tier[78] are
>>> >>>>> still running.
>>> >>>>> I'm running the v2.11 patch through my usual set of stress testing
>>> on
>>> >>>>> Linux-X64 and macOSX.
>>> >>>>>
>>> >>>>> I'm planning to do a SPECjbb2015, DaCapo-h2 and volano round on the
>>> >>>>> CR11/v2.11/14-for-jdk15 bits.
>>> >>>>>
>>> >>>>> Thanks, in advance, for any questions, comments or suggestions.
>>> >>>>>
>>> >>>>> Dan
>>> >>>>>
>>> >>>>>
>>> >>>>> On 2/26/20 5:22 PM, Daniel D. Daugherty wrote:
>>> >>>>>> Greetings,
>>> >>>>>>
>>> >>>>>> I have made changes to the Async Monitor Deflation code in
>>> >>>>>> response to
>>> >>>>>> the CR9/v2.09/12-for-jdk14 code review cycle. Thanks to Robbin
>>> >>>>>> and Erik O.
>>> >>>>>> for their comments in this round!
>>> >>>>>>
>>> >>>>>> With the extraction and push of {8235931,8236035,8235795} to
>>> >>>>>> JDK15, the
>>> >>>>>> Async Monitor Deflation code is back to "just" async deflation
>>> >>>>>> changes!
>>> >>>>>>
>>> >>>>>> I have attached the change list from CR9 to CR10 instead of
>>> >>>>>> putting it in
>>> >>>>>> the body of this email. I've also added a link to the
>>> >>>>>> CR9-to-CR10-changes
>>> >>>>>> file to the webrevs so it should be easy to find.
>>> >>>>>>
>>> >>>>>> Main bug URL:
>>> >>>>>>
>>> >>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>
>>> >>>>>> The project is currently baselined on jdk-15+11.
>>> >>>>>>
>>> >>>>>> Here's the full webrev URL for those folks that want to see all
>>> >>>>>> of the
>>> >>>>>> current Async Monitor Deflation code in one go (v2.10 full):
>>> >>>>>>
>>> >>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/13-for-jdk15+11.v2.10.full/
>>> >>>>>>
>>> >>>>>>
>>> >>>>>> Some folks might want to see just what has changed since the last
>>> >>>>>> review
>>> >>>>>> cycle so here's a webrev for that (v2.10 inc):
>>> >>>>>>
>>> >>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/13-for-jdk15+11.v2.10.inc/
>>> >>>>>>
>>> >>>>>>
>>> >>>>>> Since we backed out the HandshakeAfterDeflateIdleMonitors option
>>> >>>>>> and the
>>> >>>>>> C2 ref_count changes and updated the copyright years, the "inc"
>>> >>>>>> webrev has
>>> >>>>>> a bit more noise in it than usual. Sorry about that!
>>> >>>>>>
>>> >>>>>> The OpenJDK wiki has been updated for this round of changes:
>>> >>>>>>
>>> >>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>
>>> >>>>>>
>>> >>>>>> The jdk-15+11 based v2.10 version of the patch has been thru
>>> >>>>>> Mach5 tier[1-7]
>>> >>>>>> testing on Oracle's usual set of platforms. Mach5 tier8 is still
>>> >>>>>> running.
>>> >>>>>> I'm running the v2.10 patch through my usual set of stress
>>> >>>>>> testing on
>>> >>>>>> Linux-X64 and macOSX.
>>> >>>>>>
>>> >>>>>> I'm planning to do a SPECjbb2015 round on the
>>> >>>>>> CR10/v2.20/13-for-jdk15 bits.
>>> >>>>>>
>>> >>>>>> Thanks, in advance, for any questions, comments or suggestions.
>>> >>>>>>
>>> >>>>>> Dan
>>> >>>>>>
>>> >>>>>>
>>> >>>>>> On 2/4/20 9:41 AM, Daniel D. Daugherty wrote:
>>> >>>>>>> Greetings,
>>> >>>>>>>
>>> >>>>>>> This project is no longer targeted to JDK14 so this is NOT an
>>> >>>>>>> urgent code
>>> >>>>>>> review request.
>>> >>>>>>>
>>> >>>>>>> I've extracted the following three fixes from the Async Monitor
>>> >>>>>>> Deflation
>>> >>>>>>> project code:
>>> >>>>>>>
>>> >>>>>>> JDK-8235931 add OM_CACHE_LINE_SIZE and use smaller size on
>>> >>>>>>> SPARCv9 and X64
>>> >>>>>>> https://bugs.openjdk.java.net/browse/JDK-8235931
>>> >>>>>>>
>>> >>>>>>> JDK-8236035 refactor ObjectMonitor::set_owner() and _owner
>>> >>>>>>> field setting
>>> >>>>>>> https://bugs.openjdk.java.net/browse/JDK-8236035
>>> >>>>>>>
>>> >>>>>>> JDK-8235795 replace monitor list
>>> >>>>>>> mux{Acquire,Release}(&gListLock) with spin locks
>>> >>>>>>> https://bugs.openjdk.java.net/browse/JDK-8235795
>>> >>>>>>>
>>> >>>>>>> Each of these has been reviewed separately and will be pushed to
>>> >>>>>>> JDK15
>>> >>>>>>> in the near future (possibly by the end of this week). Of
>>> >>>>>>> course, there
>>> >>>>>>> were improvements during these review cycles and the purpose of
>>> >>>>>>> this
>>> >>>>>>> e-mail is to provided updated webrevs for this fix
>>> >>>>>>> (CR9/v2.09/12-for-jdk14)
>>> >>>>>>> within the revised context provided by {8235931, 8236035,
>>> 8235795}.
>>> >>>>>>>
>>> >>>>>>> Main bug URL:
>>> >>>>>>>
>>> >>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>
>>> >>>>>>> The project is currently baselined on jdk-14+34.
>>> >>>>>>>
>>> >>>>>>> Here's the full webrev URL for those folks that want to see all
>>> >>>>>>> of the
>>> >>>>>>> current Async Monitor Deflation code along with {8235931,
>>> >>>>>>> 8236035, 8235795}
>>> >>>>>>> in one go (v2.09b full):
>>> >>>>>>>
>>> >>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/12-for-jdk14.v2.09b.full/
>>> >>>>>>>
>>> >>>>>>>
>>> >>>>>>> Compare the open.patch file in 12-for-jdk14.v2.09.full and
>>> >>>>>>> 12-for-jdk14.v2.09b.full
>>> >>>>>>> using your favorite file comparison/merge tool to see how Async
>>> >>>>>>> Monitor Deflation
>>> >>>>>>> evolved due to {8235931, 8236035, 8235795}.
>>> >>>>>>>
>>> >>>>>>> Some folks might want to see just the Async Monitor Deflation
>>> >>>>>>> code on top of
>>> >>>>>>> {8235931, 8236035, 8235795} so here's a webrev for that (v2.09b
>>> >>>>>>> inc):
>>> >>>>>>>
>>> >>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/12-for-jdk14.v2.09b.inc/
>>> >>>>>>>
>>> >>>>>>>
>>> >>>>>>> These webrevs have gone thru several Mach5 Tier[1-8] runs along
>>> >>>>>>> with
>>> >>>>>>> my usual stress testing and SPECjbb2015 testing and there aren't
>>> >>>>>>> any
>>> >>>>>>> surprises relative to CR9/v2.09/12-for-jdk14.
>>> >>>>>>>
>>> >>>>>>> Thanks, in advance, for any questions, comments or suggestions.
>>> >>>>>>>
>>> >>>>>>> Dan
>>> >>>>>>>
>>> >>>>>>>
>>> >>>>>>> On 12/11/19 3:41 PM, Daniel D. Daugherty wrote:
>>> >>>>>>>> Greetings,
>>> >>>>>>>>
>>> >>>>>>>> I have made changes to the Async Monitor Deflation code in
>>> >>>>>>>> response to
>>> >>>>>>>> the CR8/v2.08/11-for-jdk14 code review cycle. Thanks to David
>>> >>>>>>>> H., Robbin
>>> >>>>>>>> and Erik O. for their comments!
>>> >>>>>>>>
>>> >>>>>>>> This project is no longer targeted to JDK14 so this is NOT an
>>> >>>>>>>> urgent code
>>> >>>>>>>> review request. The primary purpose of this webrev is simply to
>>> >>>>>>>> close the
>>> >>>>>>>> CR8/v2.08/11-for-jdk14 code review loop and to let folks see
>>> >>>>>>>> how I resolved
>>> >>>>>>>> the code review comments from that round.
>>> >>>>>>>>
>>> >>>>>>>> Most of the comments in the CR8/v2.08/11-for-jdk14 code review
>>> >>>>>>>> cycle were
>>> >>>>>>>> on the monitor list changes so I'm going to take a look at
>>> >>>>>>>> extracting those
>>> >>>>>>>> changes into a standalone patch. Switching from
>>> >>>>>>>> Thread::muxAcquire(&gListLock)
>>> >>>>>>>> and Thread::muxRelease(&gListLock) to finer grained internal
>>> >>>>>>>> spin locks needs
>>> >>>>>>>> to be thoroughly reviewed and the best way to do that is
>>> >>>>>>>> separately from the
>>> >>>>>>>> Async Monitor Deflation changes. Thanks to Coleen for
>>> >>>>>>>> suggesting doing this
>>> >>>>>>>> extraction earlier.
>>> >>>>>>>>
>>> >>>>>>>> I have attached the change list from CR8 to CR9 instead of
>>> >>>>>>>> putting it in
>>> >>>>>>>> the body of this email. I've also added a link to the
>>> >>>>>>>> CR8-to-CR9-changes
>>> >>>>>>>> file to the webrevs so it should be easy to find.
>>> >>>>>>>>
>>> >>>>>>>> Main bug URL:
>>> >>>>>>>>
>>> >>>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>>
>>> >>>>>>>> The project is currently baselined on jdk-14+26.
>>> >>>>>>>>
>>> >>>>>>>> Here's the full webrev URL for those folks that want to see all
>>> >>>>>>>> of the
>>> >>>>>>>> current Async Monitor Deflation code in one go (v2.09 full):
>>> >>>>>>>>
>>> >>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/12-for-jdk14.v2.09.full/
>>> >>>>>>>>
>>> >>>>>>>>
>>> >>>>>>>> Some folks might want to see just what has changed since the
>>> >>>>>>>> last review
>>> >>>>>>>> cycle so here's a webrev for that (v2.09 inc):
>>> >>>>>>>>
>>> >>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/12-for-jdk14.v2.09.inc/
>>> >>>>>>>>
>>> >>>>>>>>
>>> >>>>>>>> The OpenJDK wiki has NOT yet been updated for this round of
>>> >>>>>>>> changes:
>>> >>>>>>>>
>>> >>>>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>>>
>>> >>>>>>>>
>>> >>>>>>>> The jdk-14+26 based v2.09 version of the patch has been thru
>>> >>>>>>>> Mach5 tier[1-7]
>>> >>>>>>>> testing on Oracle's usual set of platforms. Mach5 tier8 is
>>> >>>>>>>> still running.
>>> >>>>>>>> A slightly older version of the v2.09 patch has also been
>>> >>>>>>>> through my usual
>>> >>>>>>>> set of stress testing on Linux-X64 and macOSX with the addition
>>> >>>>>>>> of Robbin's
>>> >>>>>>>> "MoCrazy 1024" test running in parallel on Linux-X64 with the
>>> >>>>>>>> other tests in
>>> >>>>>>>> my lab. The "MoCrazy 1024" has been going for > 5 days and
>>> >>>>>>>> 6700+ iterations
>>> >>>>>>>> without any failures.
>>> >>>>>>>>
>>> >>>>>>>> I'm planning to do a SPECjbb2015 round on the
>>> >>>>>>>> CR9/v2.09/12-for-jdk14 bits.
>>> >>>>>>>>
>>> >>>>>>>> Thanks, in advance, for any questions, comments or suggestions.
>>> >>>>>>>>
>>> >>>>>>>> Dan
>>> >>>>>>>>
>>> >>>>>>>>
>>> >>>>>>>> On 11/4/19 4:03 PM, Daniel D. Daugherty wrote:
>>> >>>>>>>>> Greetings,
>>> >>>>>>>>>
>>> >>>>>>>>> I have made changes to the Async Monitor Deflation code in
>>> >>>>>>>>> response to
>>> >>>>>>>>> the CR7/v2.07/10-for-jdk14 code review cycle. Thanks to David
>>> >>>>>>>>> H., Robbin
>>> >>>>>>>>> and Erik O. for their comments!
>>> >>>>>>>>>
>>> >>>>>>>>> JDK14 Rampdown phase one is coming on Dec. 12, 2019 and the
>>> >>>>>>>>> Async Monitor
>>> >>>>>>>>> Deflation project needs to push before Nov. 12, 2019 in order
>>> >>>>>>>>> to allow
>>> >>>>>>>>> for sufficient bake time for such a big change. Nov. 12 is
>>> >>>>>>>>> _next_ Tuesday
>>> >>>>>>>>> so we have 8 days from today to finish this code review cycle
>>> >>>>>>>>> and push
>>> >>>>>>>>> this code for JDK14.
>>> >>>>>>>>>
>>> >>>>>>>>> Carsten and Roman! Time for you guys to chime in again on the
>>> >>>>>>>>> code reviews.
>>> >>>>>>>>>
>>> >>>>>>>>> I have attached the change list from CR7 to CR8 instead of
>>> >>>>>>>>> putting it in
>>> >>>>>>>>> the body of this email. I've also added a link to the
>>> >>>>>>>>> CR7-to-CR8-changes
>>> >>>>>>>>> file to the webrevs so it should be easy to find.
>>> >>>>>>>>>
>>> >>>>>>>>> Main bug URL:
>>> >>>>>>>>>
>>> >>>>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>>>
>>> >>>>>>>>> The project is currently baselined on jdk-14+21.
>>> >>>>>>>>>
>>> >>>>>>>>> Here's the full webrev URL for those folks that want to see
>>> >>>>>>>>> all of the
>>> >>>>>>>>> current Async Monitor Deflation code in one go (v2.08 full):
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/11-for-jdk14.v2.08.full
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> >>>>>>>>> Some folks might want to see just what has changed since the
>>> >>>>>>>>> last review
>>> >>>>>>>>> cycle so here's a webrev for that (v2.08 inc):
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/11-for-jdk14.v2.08.inc/
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> >>>>>>>>> The OpenJDK wiki did not need any changes for this round:
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> >>>>>>>>> The jdk-14+21 based v2.08 version of the patch has been thru
>>> >>>>>>>>> Mach5 tier[1-8]
>>> >>>>>>>>> testing on Oracle's usual set of platforms. It has also been
>>> >>>>>>>>> through my usual
>>> >>>>>>>>> set of stress testing on Linux-X64, macOSX and Solaris-X64
>>> >>>>>>>>> with the addition
>>> >>>>>>>>> of Robbin's "MoCrazy 1024" test running in parallel with the
>>> >>>>>>>>> other tests in
>>> >>>>>>>>> my lab. Some testing is still running, but so far there are no
>>> >>>>>>>>> new regressions.
>>> >>>>>>>>>
>>> >>>>>>>>> I have not yet done a SPECjbb2015 round on the
>>> >>>>>>>>> CR8/v2.08/11-for-jdk14 bits.
>>> >>>>>>>>>
>>> >>>>>>>>> Thanks, in advance, for any questions, comments or suggestions.
>>> >>>>>>>>>
>>> >>>>>>>>> Dan
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> >>>>>>>>> On 10/17/19 5:50 PM, Daniel D. Daugherty wrote:
>>> >>>>>>>>>> Greetings,
>>> >>>>>>>>>>
>>> >>>>>>>>>> The Async Monitor Deflation project is reaching the end game.
>>> >>>>>>>>>> I have no
>>> >>>>>>>>>> changes planned for the project at this time so all that is
>>> >>>>>>>>>> left is code
>>> >>>>>>>>>> review and any changes that results from those reviews.
>>> >>>>>>>>>>
>>> >>>>>>>>>> Carsten and Roman! Time for you guys to chime in again on the
>>> >>>>>>>>>> code reviews.
>>> >>>>>>>>>>
>>> >>>>>>>>>> I have attached the list of fixes from CR6 to CR7 instead of
>>> >>>>>>>>>> putting it
>>> >>>>>>>>>> in the main body of this email.
>>> >>>>>>>>>>
>>> >>>>>>>>>> Main bug URL:
>>> >>>>>>>>>>
>>> >>>>>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>>>>
>>> >>>>>>>>>> The project is currently baselined on jdk-14+19.
>>> >>>>>>>>>>
>>> >>>>>>>>>> Here's the full webrev URL for those folks that want to see
>>> >>>>>>>>>> all of the
>>> >>>>>>>>>> current Async Monitor Deflation code in one go (v2.07 full):
>>> >>>>>>>>>>
>>> >>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/10-for-jdk14.v2.07.full
>>> >>>>>>>>>>
>>> >>>>>>>>>>
>>> >>>>>>>>>> Some folks might want to see just what has changed since the
>>> >>>>>>>>>> last review
>>> >>>>>>>>>> cycle so here's a webrev for that (v2.07 inc):
>>> >>>>>>>>>>
>>> >>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/10-for-jdk14.v2.07.inc/
>>> >>>>>>>>>>
>>> >>>>>>>>>>
>>> >>>>>>>>>> The OpenJDK wiki has been updated to match the
>>> >>>>>>>>>> CR7/v2.07/10-for-jdk14 changes:
>>> >>>>>>>>>>
>>> >>>>>>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>>>>>
>>> >>>>>>>>>>
>>> >>>>>>>>>> The jdk-14+18 based v2.07 version of the patch has been thru
>>> >>>>>>>>>> Mach5 tier[1-8]
>>> >>>>>>>>>> testing on Oracle's usual set of platforms. It has also been
>>> >>>>>>>>>> through my usual
>>> >>>>>>>>>> set of stress testing on Linux-X64, macOSX and Solaris-X64
>>> >>>>>>>>>> with the addition
>>> >>>>>>>>>> of Robbin's "MoCrazy 1024" test running in parallel with the
>>> >>>>>>>>>> other tests in
>>> >>>>>>>>>> my lab.
>>> >>>>>>>>>>
>>> >>>>>>>>>> The jdk-14+19 based v2.07 version of the patch has been thru
>>> >>>>>>>>>> Mach5 tier[1-3]
>>> >>>>>>>>>> test on Oracle's usual set of platforms. Mach5 tier[4-8] are
>>> >>>>>>>>>> in process.
>>> >>>>>>>>>>
>>> >>>>>>>>>> I did another round of SPECjbb2015 testing in Oracle's Aurora
>>> >>>>>>>>>> Performance lab
>>> >>>>>>>>>> using using their tuned SPECjbb2015 Linux-X64 G1 configs:
>>> >>>>>>>>>>
>>> >>>>>>>>>> - "base" is jdk-14+18
>>> >>>>>>>>>> - "v2.07" is the latest version and includes C2
>>> >>>>>>>>>> inc_om_ref_count() support
>>> >>>>>>>>>> on LP64 X64 and the new
>>> >>>>>>>>>> HandshakeAfterDeflateIdleMonitors option
>>> >>>>>>>>>> - "off" is with -XX:-AsyncDeflateIdleMonitors specified
>>> >>>>>>>>>> - "handshake" is with
>>> >>>>>>>>>> -XX:+HandshakeAfterDeflateIdleMonitors specified
>>> >>>>>>>>>>
>>> >>>>>>>>>> hbIR hbIR
>>> >>>>>>>>>> (max attempted) (settled) max-jOPS critical-jOPS runtime
>>> >>>>>>>>>> --------------- --------- -------- ------------- -------
>>> >>>>>>>>>> 34282.00 30635.90 28831.30 20969.20 3841.30 base
>>> >>>>>>>>>> 34282.00 30973.00 29345.80 21025.20 3964.10
>>> v2.07
>>> >>>>>>>>>> 34282.00 31105.60 29174.30 21074.00 3931.30
>>> >>>>>>>>>> v2.07_handshake
>>> >>>>>>>>>> 34282.00 30789.70 27151.60 19839.10 3850.20
>>> >>>>>>>>>> v2.07_off
>>> >>>>>>>>>>
>>> >>>>>>>>>> - The Aurora Perf comparison tool reports:
>>> >>>>>>>>>>
>>> >>>>>>>>>> Comparison max-jOPS critical-jOPS
>>> >>>>>>>>>> ---------------------- --------------------
>>> >>>>>>>>>> --------------------
>>> >>>>>>>>>> base vs 2.07 +1.78% (s, p=0.000) +0.27%
>>> >>>>>>>>>> (ns, p=0.790)
>>> >>>>>>>>>> base vs 2.07_handshake +1.19% (s, p=0.007) +0.58%
>>> >>>>>>>>>> (ns, p=0.536)
>>> >>>>>>>>>> base vs 2.07_off -5.83% (ns, p=0.394) -5.39%
>>> >>>>>>>>>> (ns, p=0.347)
>>> >>>>>>>>>>
>>> >>>>>>>>>> (s) - significant (ns) - not-significant
>>> >>>>>>>>>>
>>> >>>>>>>>>> - For historical comparison, the Aurora Perf comparision
>>> >>>>>>>>>> tool
>>> >>>>>>>>>> reported for v2.06 with a baseline of jdk-13+31:
>>> >>>>>>>>>>
>>> >>>>>>>>>> Comparison max-jOPS critical-jOPS
>>> >>>>>>>>>> ---------------------- --------------------
>>> >>>>>>>>>> --------------------
>>> >>>>>>>>>> base vs 2.06 -0.32% (ns, p=0.345) +0.71%
>>> >>>>>>>>>> (ns, p=0.646)
>>> >>>>>>>>>> base vs 2.06_off +0.49% (ns, p=0.292) -1.21%
>>> >>>>>>>>>> (ns, p=0.481)
>>> >>>>>>>>>>
>>> >>>>>>>>>> (s) - significant (ns) - not-significant
>>> >>>>>>>>>>
>>> >>>>>>>>>> Thanks, in advance, for any questions, comments or
>>> suggestions.
>>> >>>>>>>>>>
>>> >>>>>>>>>> Dan
>>> >>>>>>>>>>
>>> >>>>>>>>>>
>>> >>>>>>>>>> On 8/28/19 5:02 PM, Daniel D. Daugherty wrote:
>>> >>>>>>>>>>> Greetings,
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> The Async Monitor Deflation project has rebased to JDK14 so
>>> >>>>>>>>>>> it's time
>>> >>>>>>>>>>> for our first code review in that new context!!
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> I've been focused on changing the monitor list management
>>> >>>>>>>>>>> code to be
>>> >>>>>>>>>>> lock-free in order to make SPECjbb2015 happier. Of course
>>> >>>>>>>>>>> with a change
>>> >>>>>>>>>>> like that, it takes a while to chase down all the new and
>>> >>>>>>>>>>> wonderful
>>> >>>>>>>>>>> races. At this point, I have the code back to the same
>>> >>>>>>>>>>> stability that
>>> >>>>>>>>>>> I had with CR5/v2.05/8-for-jdk13.
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> To lay the ground work for this round of review, I pushed
>>> >>>>>>>>>>> the following
>>> >>>>>>>>>>> two fixes to jdk/jdk earlier today:
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> JDK-8230184 rename, whitespace, indent and comments
>>> >>>>>>>>>>> changes in preparation
>>> >>>>>>>>>>> for lock free Monitor lists
>>> >>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8230184
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> JDK-8230317 serviceability/sa/ClhsdbPrintStatics.java
>>> >>>>>>>>>>> fails after 8230184
>>> >>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8230317
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> I have attached the list of fixes from CR5 to CR6 instead of
>>> >>>>>>>>>>> putting
>>> >>>>>>>>>>> in the main body of this email.
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> Main bug URL:
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> The project is currently baselined on jdk-14+11 plus the
>>> >>>>>>>>>>> fixes for
>>> >>>>>>>>>>> JDK-8230184 and JDK-8230317.
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> Here's the full webrev URL for those folks that want to see
>>> >>>>>>>>>>> all of the
>>> >>>>>>>>>>> current Async Monitor Deflation code in one go (v2.06 full):
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/9-for-jdk14.v2.06.full/
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> The primary focus of this review cycle is on the lock-free
>>> >>>>>>>>>>> Monitor List
>>> >>>>>>>>>>> management changes so here's a webrev for just that patch
>>> >>>>>>>>>>> (v2.06c):
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/9-for-jdk14.v2.06c.inc/
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> The secondary focus of this review cycle is on the bug fixes
>>> >>>>>>>>>>> that have
>>> >>>>>>>>>>> been made since CR5/v2.05/8-for-jdk13 so here's a webrev for
>>> >>>>>>>>>>> just that
>>> >>>>>>>>>>> patch (v2.06b):
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/9-for-jdk14.v2.06b.inc/
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> The third and final bucket for this review cycle is the
>>> >>>>>>>>>>> rename, whitespace,
>>> >>>>>>>>>>> indent and comments changes made in preparation for lock
>>> >>>>>>>>>>> free Monitor list
>>> >>>>>>>>>>> management. Almost all of that was extracted into
>>> >>>>>>>>>>> JDK-8230184 for the
>>> >>>>>>>>>>> baseline so this bucket now has just a few comment changes
>>> >>>>>>>>>>> relative to
>>> >>>>>>>>>>> CR5/v2.05/8-for-jdk13. Here's a webrev for the remainder
>>> >>>>>>>>>>> (v2.06a):
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/9-for-jdk14.v2.06a.inc/
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> Some folks might want to see just what has changed since the
>>> >>>>>>>>>>> last review
>>> >>>>>>>>>>> cycle so here's a webrev for that (v2.06 inc):
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/9-for-jdk14.v2.06.inc/
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> Last, but not least, some folks might want to see the code
>>> >>>>>>>>>>> before the
>>> >>>>>>>>>>> addition of lock-free Monitor List management so here's a
>>> >>>>>>>>>>> webrev for
>>> >>>>>>>>>>> that (v2.00 -> v2.05):
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/9-for-jdk14.v2.05.inc/
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> The OpenJDK wiki will need minor updates to match the CR6
>>> >>>>>>>>>>> changes:
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> but that should only be changes to describe per-thread list
>>> >>>>>>>>>>> async monitor
>>> >>>>>>>>>>> deflation being done by the ServiceThread.
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> (I did update the OpenJDK wiki for the CR5 changes back on
>>> >>>>>>>>>>> 2019.08.14)
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> This version of the patch has been thru Mach5 tier[1-8]
>>> >>>>>>>>>>> testing on
>>> >>>>>>>>>>> Oracle's usual set of platforms. It has also been through my
>>> >>>>>>>>>>> usual set
>>> >>>>>>>>>>> of stress testing on Linux-X64, macOSX and Solaris-X64.
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> I did a bunch of SPECjbb2015 testing in Oracle's Aurora
>>> >>>>>>>>>>> Performance lab
>>> >>>>>>>>>>> using using their tuned SPECjbb2015 Linux-X64 G1 configs.
>>> >>>>>>>>>>> This was using
>>> >>>>>>>>>>> this patch baselined on jdk-13+31 (for stability):
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> hbIR hbIR
>>> >>>>>>>>>>> (max attempted) (settled) max-jOPS critical-jOPS
>>> runtime
>>> >>>>>>>>>>> --------------- --------- -------- -------------
>>> -------
>>> >>>>>>>>>>> 34282.00 28837.20 27905.20 19817.40 3658.10
>>> base
>>> >>>>>>>>>>> 34965.70 29798.80 27814.90 19959.00 3514.60
>>> >>>>>>>>>>> v2.06d
>>> >>>>>>>>>>> 34282.00 29100.70 28042.50 19577.00 3701.90
>>> >>>>>>>>>>> v2.06d_off
>>> >>>>>>>>>>> 34282.00 29218.50 27562.80 19397.30 3657.60
>>> >>>>>>>>>>> v2.06d_ocache
>>> >>>>>>>>>>> 34965.70 29838.30 26512.40 19170.60 3569.90
>>> >>>>>>>>>>> v2.05
>>> >>>>>>>>>>> 34282.00 28926.10 27734.00 19835.10 3588.40
>>> >>>>>>>>>>> v2.05_off
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> The "off" configs are with -XX:-AsyncDeflateIdleMonitors
>>> >>>>>>>>>>> specified and
>>> >>>>>>>>>>> the "ocache" config is with 128 byte cache line sizes
>>> >>>>>>>>>>> instead of 64 byte
>>> >>>>>>>>>>> cache lines sizes. "v2.06d" is the last set of changes that
>>> >>>>>>>>>>> I made before
>>> >>>>>>>>>>> those changes were distributed into the "v2.06a", "v2.06b"
>>> >>>>>>>>>>> and "v2.06c"
>>> >>>>>>>>>>> buckets for this review recycle.
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> Thanks, in advance, for any questions, comments or
>>> suggestions.
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> Dan
>>> >>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>> On 7/11/19 3:49 PM, Daniel D. Daugherty wrote:
>>> >>>>>>>>>>>> Greetings,
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> I've been focused on chasing down and fixing the rare test
>>> >>>>>>>>>>>> failures
>>> >>>>>>>>>>>> that only pop up rarely. So this round is primarily fixes
>>> >>>>>>>>>>>> for races
>>> >>>>>>>>>>>> with a few additional fixes that came from Karen's review
>>> >>>>>>>>>>>> of CR4.
>>> >>>>>>>>>>>> Thanks Karen!
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> I have attached the list of fixes from CR4 to CR5 instead
>>> >>>>>>>>>>>> of putting
>>> >>>>>>>>>>>> in the main body of this email.
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> Main bug URL:
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> The project is currently baselined on jdk-13+29. This will
>>> >>>>>>>>>>>> likely be
>>> >>>>>>>>>>>> the last JDK13 baseline for this project and I'll roll to
>>> >>>>>>>>>>>> the JDK14
>>> >>>>>>>>>>>> (jdk/jdk) repo soon...
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> Here's the full webrev URL:
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/8-for-jdk13.full/
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> Here's the incremental webrev URL:
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/8-for-jdk13.inc/
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> I have not yet checked the OpenJDK wiki to see if it needs
>>> >>>>>>>>>>>> any updates
>>> >>>>>>>>>>>> to match the CR5 changes:
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> (I did update the OpenJDK wiki for the CR4 changes back on
>>> >>>>>>>>>>>> 2019.06.26)
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> This version of the patch has been thru Mach5 tier[1-3]
>>> >>>>>>>>>>>> testing on
>>> >>>>>>>>>>>> Oracle's usual set of platforms. Mach5 tier[4-6] is running
>>> >>>>>>>>>>>> now and
>>> >>>>>>>>>>>> Mach5 tier[78] will follow. I'll kick off the usual stress
>>> >>>>>>>>>>>> testing
>>> >>>>>>>>>>>> on Linux-X64, macOSX and Solaris-X64 as those machines
>>> >>>>>>>>>>>> become available.
>>> >>>>>>>>>>>> Since I haven't made any performance changes in this round,
>>> >>>>>>>>>>>> I'll only
>>> >>>>>>>>>>>> be running SPECjbb2015 to gather the latest
>>> >>>>>>>>>>>> monitorinflation logs.
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> Next up:
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> - We're still seeing 4-5% lower performance with
>>> >>>>>>>>>>>> SPECjbb2015 on
>>> >>>>>>>>>>>> Linux-X64 and we've determined that some of that comes
>>> from
>>> >>>>>>>>>>>> contention on the gListLock. So I'm going to investigate
>>> >>>>>>>>>>>> removing
>>> >>>>>>>>>>>> the gListLock. Yes, another lock free set of changes is
>>> >>>>>>>>>>>> coming!
>>> >>>>>>>>>>>> - Of course, going lock free often causes new races and new
>>> >>>>>>>>>>>> failures
>>> >>>>>>>>>>>> so that's a good reason for make those changes isolated
>>> >>>>>>>>>>>> in their
>>> >>>>>>>>>>>> own round (and not holding up CR5/v2.05/8-for-jdk13
>>> >>>>>>>>>>>> anymore).
>>> >>>>>>>>>>>> - I finally have a potential fix for the Win* failure with
>>> >>>>>>>>>>>> gc/g1/humongousObjects/TestHumongousClassLoader.java
>>> >>>>>>>>>>>> but I haven't run it through Mach5 yet so it'll be in the
>>> >>>>>>>>>>>> next round.
>>> >>>>>>>>>>>> - Some RTM tests were recently re-enabled in Mach5 and I'm
>>> >>>>>>>>>>>> seeing some
>>> >>>>>>>>>>>> monitor related failures there. I suspect that I need to
>>> >>>>>>>>>>>> go take a
>>> >>>>>>>>>>>> look at the C2 RTM macro assembler code and look for
>>> >>>>>>>>>>>> things that might
>>> >>>>>>>>>>>> conflict if Async Monitor Deflation. If you're interested
>>> >>>>>>>>>>>> in that kind
>>> >>>>>>>>>>>> of issue, then see the macroAssembler_x86.cpp sanity
>>> >>>>>>>>>>>> check that I
>>> >>>>>>>>>>>> added in this round!
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> Thanks, in advance, for any questions, comments or
>>> >>>>>>>>>>>> suggestions.
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> Dan
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>> On 5/26/19 8:30 PM, Daniel D. Daugherty wrote:
>>> >>>>>>>>>>>>> Greetings,
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> I have a fix for an issue that came up during performance
>>> >>>>>>>>>>>>> testing.
>>> >>>>>>>>>>>>> Many thanks to Robbin for diagnosing the issue in his
>>> >>>>>>>>>>>>> SPECjbb2015
>>> >>>>>>>>>>>>> experiments.
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> Here's the list of changes from CR3 to CR4. The list is a
>>> bit
>>> >>>>>>>>>>>>> verbose due to the complexity of the issue, but the changes
>>> >>>>>>>>>>>>> themselves are not that big.
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> Functional:
>>> >>>>>>>>>>>>> - Change SafepointSynchronize::is_cleanup_needed() from
>>> >>>>>>>>>>>>> calling
>>> >>>>>>>>>>>>> ObjectSynchronizer::is_cleanup_needed() to calling
>>> >>>>>>>>>>>>> ObjectSynchronizer::is_safepoint_deflation_needed():
>>> >>>>>>>>>>>>> - is_safepoint_deflation_needed() returns the result of
>>> >>>>>>>>>>>>> monitors_used_above_threshold() for safepoint based
>>> >>>>>>>>>>>>> monitor deflation (!AsyncDeflateIdleMonitors).
>>> >>>>>>>>>>>>> - For AsyncDeflateIdleMonitors, it only returns true if
>>> >>>>>>>>>>>>> there is a special deflation request, e.g.,
>>> System.gc()
>>> >>>>>>>>>>>>> - This solves a bug where there are a bunch of
>>> Cleanup
>>> >>>>>>>>>>>>> safepoints that simply request async deflation
>>> which
>>> >>>>>>>>>>>>> keeps the async JavaThreads from making progress on
>>> >>>>>>>>>>>>> their async deflation work.
>>> >>>>>>>>>>>>> - Add AsyncDeflationInterval diagnostic option.
>>> >>>>>>>>>>>>> Description:
>>> >>>>>>>>>>>>> Async deflate idle monitors every so many
>>> >>>>>>>>>>>>> milliseconds when
>>> >>>>>>>>>>>>> MonitorUsedDeflationThreshold is exceeded (0 is off).
>>> >>>>>>>>>>>>> - Replace
>>> >>>>>>>>>>>>> ObjectSynchronizer::gOmShouldDeflateIdleMonitors() with
>>> >>>>>>>>>>>>> ObjectSynchronizer::is_async_deflation_needed():
>>> >>>>>>>>>>>>> - is_async_deflation_needed() returns true when
>>> >>>>>>>>>>>>> is_async_cleanup_requested() is true or when
>>> >>>>>>>>>>>>> monitors_used_above_threshold() is true (but no more
>>> >>>>>>>>>>>>> often than
>>> >>>>>>>>>>>>> AsyncDeflationInterval).
>>> >>>>>>>>>>>>> - if AsyncDeflateIdleMonitors Service_lock->wait() now
>>> >>>>>>>>>>>>> waits for
>>> >>>>>>>>>>>>> at most GuaranteedSafepointInterval millis:
>>> >>>>>>>>>>>>> - This allows is_async_deflation_needed() to be
>>> >>>>>>>>>>>>> checked at
>>> >>>>>>>>>>>>> the same interval as GuaranteedSafepointInterval.
>>> >>>>>>>>>>>>> (default is 1000 millis/1 second)
>>> >>>>>>>>>>>>> - Once is_async_deflation_needed() has returned
>>> >>>>>>>>>>>>> true, it
>>> >>>>>>>>>>>>> generally cannot return true for
>>> >>>>>>>>>>>>> AsyncDeflationInterval.
>>> >>>>>>>>>>>>> This is to prevent async deflation from swamping
>>> the
>>> >>>>>>>>>>>>> ServiceThread.
>>> >>>>>>>>>>>>> - The ServiceThread still handles async deflation of the
>>> >>>>>>>>>>>>> global
>>> >>>>>>>>>>>>> in-use list and now it also marks JavaThreads for
>>> >>>>>>>>>>>>> async deflation
>>> >>>>>>>>>>>>> of their in-use lists.
>>> >>>>>>>>>>>>> - The ServiceThread will check for async deflation
>>> >>>>>>>>>>>>> work every
>>> >>>>>>>>>>>>> GuaranteedSafepointInterval.
>>> >>>>>>>>>>>>> - A safepoint can still cause the ServiceThread to
>>> >>>>>>>>>>>>> check for
>>> >>>>>>>>>>>>> async deflation work via
>>> is_async_deflation_requested.
>>> >>>>>>>>>>>>> - Refactor code from
>>> >>>>>>>>>>>>> ObjectSynchronizer::is_cleanup_needed() into
>>> >>>>>>>>>>>>> monitors_used_above_threshold() and remove
>>> >>>>>>>>>>>>> is_cleanup_needed().
>>> >>>>>>>>>>>>> - In addition to System.gc(), the VM_Exit VM op and the
>>> >>>>>>>>>>>>> final
>>> >>>>>>>>>>>>> VMThread safepoint now set the
>>> >>>>>>>>>>>>> is_special_deflation_requested
>>> >>>>>>>>>>>>> flag to reduce the in-use monitor population that is
>>> >>>>>>>>>>>>> reported by
>>> >>>>>>>>>>>>> ObjectSynchronizer::log_in_use_monitor_details() at VM
>>> exit.
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> Test update:
>>> >>>>>>>>>>>>> - test/hotspot/gtest/oops/test_markOop.cpp is updated to
>>> >>>>>>>>>>>>> work with
>>> >>>>>>>>>>>>> AsyncDeflateIdleMonitors.
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> Collateral:
>>> >>>>>>>>>>>>> - Add/clarify/update some logging messages.
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> Cleanup:
>>> >>>>>>>>>>>>> - Updated comments based on Karen's code review.
>>> >>>>>>>>>>>>> - Change 'special cleanup' -> 'special deflation' and
>>> >>>>>>>>>>>>> 'async cleanup' -> 'async deflation'.
>>> >>>>>>>>>>>>> - comment and function name changes
>>> >>>>>>>>>>>>> - Clarify MonitorUsedDeflationThreshold description;
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> Main bug URL:
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> The project is currently baselined on jdk-13+22.
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> Here's the full webrev URL:
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/7-for-jdk13.full/
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> Here's the incremental webrev URL:
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/7-for-jdk13.inc/
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> I have not updated the OpenJDK wiki to reflect the CR4
>>> >>>>>>>>>>>>> changes:
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> The wiki doesn't say a whole lot about the async deflation
>>> >>>>>>>>>>>>> invocation
>>> >>>>>>>>>>>>> mechanism so I have to figure out how to add that content.
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> This version of the patch has been thru Mach5 tier[1-8]
>>> >>>>>>>>>>>>> testing on
>>> >>>>>>>>>>>>> Oracle's usual set of platforms. My Solaris-X64 stress kit
>>> >>>>>>>>>>>>> run is
>>> >>>>>>>>>>>>> running now. Kitchensink8H on product, fastdebug, and
>>> >>>>>>>>>>>>> slowdebug bits
>>> >>>>>>>>>>>>> are running on Linux-X64, MacOSX and Solaris-X64. I still
>>> >>>>>>>>>>>>> have to run
>>> >>>>>>>>>>>>> my stress kit on Linux-X64. I still have to run the
>>> >>>>>>>>>>>>> SPECjbb2015
>>> >>>>>>>>>>>>> baseline and CR4 runs on Linux-X64, MacOSX and Solaris-X64.
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> Thanks, in advance, for any questions, comments or
>>> >>>>>>>>>>>>> suggestions.
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> Dan
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>> On 5/6/19 11:52 AM, Daniel D. Daugherty wrote:
>>> >>>>>>>>>>>>>> Greetings,
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> I had some discussions with Karen about a race that was
>>> >>>>>>>>>>>>>> in the
>>> >>>>>>>>>>>>>> ObjectMonitor::enter() code in CR2/v2.02/5-for-jdk13.
>>> >>>>>>>>>>>>>> This race was
>>> >>>>>>>>>>>>>> theoretical and I had no test failures due to it. The fix
>>> >>>>>>>>>>>>>> is pretty
>>> >>>>>>>>>>>>>> simple: remove the special case code for async deflation
>>> >>>>>>>>>>>>>> in the
>>> >>>>>>>>>>>>>> ObjectMonitor::enter() function and rely solely on the
>>> >>>>>>>>>>>>>> ref_count
>>> >>>>>>>>>>>>>> for ObjectMonitor::enter() protection.
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> During those discussions Karen also floated the idea of
>>> >>>>>>>>>>>>>> using the
>>> >>>>>>>>>>>>>> ref_count field instead of the contentions field for the
>>> >>>>>>>>>>>>>> Async
>>> >>>>>>>>>>>>>> Monitor Deflation protocol. I decided to go ahead and
>>> >>>>>>>>>>>>>> code up that
>>> >>>>>>>>>>>>>> change and I have run it through the usual stress and
>>> >>>>>>>>>>>>>> Mach5 testing
>>> >>>>>>>>>>>>>> with no issues. It's also known as v2.03 (for those for
>>> >>>>>>>>>>>>>> with the
>>> >>>>>>>>>>>>>> patches) and as webrev/6-for-jdk13 (for those with webrev
>>> >>>>>>>>>>>>>> URLs).
>>> >>>>>>>>>>>>>> Sorry for all the names...
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> Main bug URL:
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> The project is currently baselined on jdk-13+18.
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> Here's the full webrev URL:
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/6-for-jdk13.full/
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> Here's the incremental webrev URL:
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/6-for-jdk13.inc/
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> I have also updated the OpenJDK wiki to reflect the CR3
>>> >>>>>>>>>>>>>> changes:
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> This version of the patch has been thru Mach5 tier[1-8]
>>> >>>>>>>>>>>>>> testing on
>>> >>>>>>>>>>>>>> Oracle's usual set of platforms. My Solaris-X64 stress
>>> >>>>>>>>>>>>>> kit run had
>>> >>>>>>>>>>>>>> no issues. Kitchensink8H on product, fastdebug, and
>>> >>>>>>>>>>>>>> slowdebug bits
>>> >>>>>>>>>>>>>> had no failures on Linux-X64; MacOSX fastdebug and
>>> >>>>>>>>>>>>>> slowdebug and
>>> >>>>>>>>>>>>>> Solaris-X64 release had the usual "Too large time diff"
>>> >>>>>>>>>>>>>> complaints.
>>> >>>>>>>>>>>>>> 12 hour Inflate2 runs on product, fastdebug and slowdebug
>>> >>>>>>>>>>>>>> bits on
>>> >>>>>>>>>>>>>> Linux-X64, MacOSX and Solaris-X64 had no failures. My
>>> >>>>>>>>>>>>>> Linux-X64
>>> >>>>>>>>>>>>>> stress kit is running right now.
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> I've done the SPECjbb2015 baseline and CR3 runs. I need
>>> >>>>>>>>>>>>>> to gather
>>> >>>>>>>>>>>>>> the results and analyze them.
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> Thanks, in advance, for any questions, comments or
>>> >>>>>>>>>>>>>> suggestions.
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> Dan
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>> On 4/25/19 12:38 PM, Daniel D. Daugherty wrote:
>>> >>>>>>>>>>>>>>> Greetings,
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> I have a small but important bug fix for the Async
>>> >>>>>>>>>>>>>>> Monitor Deflation
>>> >>>>>>>>>>>>>>> project ready to go. It's also known as v2.02 (for those
>>> >>>>>>>>>>>>>>> for with the
>>> >>>>>>>>>>>>>>> patches) and as webrev/5-for-jdk13 (for those with
>>> >>>>>>>>>>>>>>> webrev URLs). Sorry
>>> >>>>>>>>>>>>>>> for all the names...
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> JDK-8222295 was pushed to jdk/jdk two days ago so that
>>> >>>>>>>>>>>>>>> baseline patch
>>> >>>>>>>>>>>>>>> is out of our hair.
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> Main bug URL:
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> The project is currently baselined on jdk-13+17.
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> Here's the full webrev URL:
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/5-for-jdk13.full/
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> Here's the incremental webrev URL (JDK-8153224):
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/5-for-jdk13.inc/
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> I still have to update the OpenJDK wiki to reflect the
>>> >>>>>>>>>>>>>>> CR2 changes:
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> This version of the patch has been thru Mach5 tier[1-6]
>>> >>>>>>>>>>>>>>> testing on
>>> >>>>>>>>>>>>>>> Oracle's usual set of platforms. Mach5 tier[7-8] is
>>> >>>>>>>>>>>>>>> running now.
>>> >>>>>>>>>>>>>>> My stress kit is running on Solaris-X64 now.
>>> >>>>>>>>>>>>>>> Kitchensink8H is running
>>> >>>>>>>>>>>>>>> now on product, fastdebug, and slowdebug bits on
>>> >>>>>>>>>>>>>>> Linux-X64, MacOSX
>>> >>>>>>>>>>>>>>> and Solaris-X64. 12 hour Inflate2 runs are running now
>>> >>>>>>>>>>>>>>> on product,
>>> >>>>>>>>>>>>>>> fastdebug and slowdebug bits on Linux-X64, MacOSX and
>>> >>>>>>>>>>>>>>> Solaris-X64.
>>> >>>>>>>>>>>>>>> I'll start my my stress kit on Linux-X64 sometime on
>>> >>>>>>>>>>>>>>> Sunday (after
>>> >>>>>>>>>>>>>>> my jdk-13+18 stress run is done).
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> I'll do SPECjbb2015 baseline and CR2 runs after all the
>>> >>>>>>>>>>>>>>> stress
>>> >>>>>>>>>>>>>>> testing is done.
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> Thanks, in advance, for any questions, comments or
>>> >>>>>>>>>>>>>>> suggestions.
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> Dan
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>> On 4/19/19 11:58 AM, Daniel D. Daugherty wrote:
>>> >>>>>>>>>>>>>>>> Greetings,
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> I finally have CR1 for the Async Monitor Deflation
>>> >>>>>>>>>>>>>>>> project ready to
>>> >>>>>>>>>>>>>>>> go. It's also known as v2.01 (for those for with the
>>> >>>>>>>>>>>>>>>> patches) and as
>>> >>>>>>>>>>>>>>>> webrev/4-for-jdk13 (for those with webrev URLs). Sorry
>>> >>>>>>>>>>>>>>>> for all the
>>> >>>>>>>>>>>>>>>> names...
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> Main bug URL:
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> Baseline bug fixes URL:
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> JDK-8222295 more baseline cleanups from Async
>>> >>>>>>>>>>>>>>>> Monitor Deflation project
>>> >>>>>>>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8222295
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> The project is currently baselined on jdk-13+15.
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> Here's the webrev for the latest baseline changes
>>> >>>>>>>>>>>>>>>> (JDK-8222295):
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/4-for-jdk13.8222295
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> Here's the full webrev URL (JDK-8153224 only):
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/4-for-jdk13.full/
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> Here's the incremental webrev URL (JDK-8153224):
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/4-for-jdk13.inc/
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> So I'm looking for reviews for both JDK-8222295 and the
>>> >>>>>>>>>>>>>>>> latest version
>>> >>>>>>>>>>>>>>>> of JDK-8153224...
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> I still have to update the OpenJDK wiki to reflect the
>>> >>>>>>>>>>>>>>>> CR changes:
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> This version of the patch has been thru Mach5 tier[1-3]
>>> >>>>>>>>>>>>>>>> testing on
>>> >>>>>>>>>>>>>>>> Oracle's usual set of platforms. Mach5 tier[4-6] is
>>> >>>>>>>>>>>>>>>> running now and
>>> >>>>>>>>>>>>>>>> Mach5 tier[78] will be run later today. My stress kit
>>> >>>>>>>>>>>>>>>> on Solaris-X64
>>> >>>>>>>>>>>>>>>> is running now. Linux-X64 stress testing will start on
>>> >>>>>>>>>>>>>>>> Sunday. I'm
>>> >>>>>>>>>>>>>>>> planning to do Kitchensink runs, SPECjbb2015 runs and
>>> >>>>>>>>>>>>>>>> my monitor
>>> >>>>>>>>>>>>>>>> inflation stress tests on Linux-X64, MacOSX and
>>> >>>>>>>>>>>>>>>> Solaris-X64.
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> Thanks, in advance, for any questions, comments or
>>> >>>>>>>>>>>>>>>> suggestions.
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> Dan
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>> On 3/24/19 9:57 AM, Daniel D. Daugherty wrote:
>>> >>>>>>>>>>>>>>>>> Greetings,
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> Welcome to the OpenJDK review thread for my port of
>>> >>>>>>>>>>>>>>>>> Carsten's work on:
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> JDK-8153224 Monitor deflation prolong safepoints
>>> >>>>>>>>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8153224
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> Here's a link to the OpenJDK wiki that describes my
>>> port:
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> Here's the webrev URL:
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~dcubed/8153224-webrev/3-for-jdk13/
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> Here's a link to Carsten's original webrev:
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>>
>>> http://cr.openjdk.java.net/~cvarming/monitor_deflate_conc/0/
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> Earlier versions of this patch have been through
>>> >>>>>>>>>>>>>>>>> several rounds of
>>> >>>>>>>>>>>>>>>>> preliminary review. Many thanks to Carsten, Coleen,
>>> >>>>>>>>>>>>>>>>> Robbin, and
>>> >>>>>>>>>>>>>>>>> Roman for their preliminary code review comments. A
>>> >>>>>>>>>>>>>>>>> very special
>>> >>>>>>>>>>>>>>>>> thanks to Robbin and Roman for building and testing
>>> >>>>>>>>>>>>>>>>> the patch in
>>> >>>>>>>>>>>>>>>>> their own environments (including specJBB2015).
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> This version of the patch has been thru Mach5
>>> >>>>>>>>>>>>>>>>> tier[1-8] testing on
>>> >>>>>>>>>>>>>>>>> Oracle's usual set of platforms. Earlier versions have
>>> >>>>>>>>>>>>>>>>> been run
>>> >>>>>>>>>>>>>>>>> through my stress kit on my Linux-X64 and Solaris-X64
>>> >>>>>>>>>>>>>>>>> servers
>>> >>>>>>>>>>>>>>>>> (product, fastdebug, slowdebug).Earlier versions have
>>> >>>>>>>>>>>>>>>>> run Kitchensink
>>> >>>>>>>>>>>>>>>>> for 12 hours on MacOSX, Linux-X64 and Solaris-X64
>>> >>>>>>>>>>>>>>>>> (product, fastdebug
>>> >>>>>>>>>>>>>>>>> and slowdebug). Earlier versions have run my monitor
>>> >>>>>>>>>>>>>>>>> inflation stress
>>> >>>>>>>>>>>>>>>>> tests for 12 hours on MacOSX, Linux-X64 and
>>> >>>>>>>>>>>>>>>>> Solaris-X64 (product,
>>> >>>>>>>>>>>>>>>>> fastdebug and slowdebug).
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> All of the testing done on earlier versions will be
>>> >>>>>>>>>>>>>>>>> redone on the
>>> >>>>>>>>>>>>>>>>> latest version of the patch.
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> Thanks, in advance, for any questions, comments or
>>> >>>>>>>>>>>>>>>>> suggestions.
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> Dan
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>> P.S.
>>> >>>>>>>>>>>>>>>>> One subtest in
>>> >>>>>>>>>>>>>>>>> gc/g1/humongousObjects/TestHumongousClassLoader.java
>>> >>>>>>>>>>>>>>>>> is currently failing in -Xcomp mode on Win* only. I've
>>> >>>>>>>>>>>>>>>>> been trying
>>> >>>>>>>>>>>>>>>>> to characterize/analyze this failure for more than a
>>> >>>>>>>>>>>>>>>>> week now. At
>>> >>>>>>>>>>>>>>>>> this point I'm convinced that Async Monitor Deflation
>>> >>>>>>>>>>>>>>>>> is aggravating
>>> >>>>>>>>>>>>>>>>> an existing bug. However, I plan to have a better
>>> >>>>>>>>>>>>>>>>> handle on that
>>> >>>>>>>>>>>>>>>>> failure before these bits are pushed to the jdk/jdk
>>> repo.
>>> >>>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>>
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>>
>>> >>>>>>>>>>>>
>>> >>>>>>>>>>>
>>> >>>>>>>>>>
>>> >>>>>>>>>
>>> >>>>>>>>
>>> >>>>>>>
>>> >>>>>>
>>> >>>>>
>>> >>>>
>>> >>>
>>> >>
>>>
>>>
>>
>
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