Java Performance Degradation in JDK7 and JDK8
Jacob Wieland
wieland at testingtech.com
Thu Apr 30 15:15:14 UTC 2015
thank you very much - very interesting.
is there any estimate when a patch for 7/8 will be available?
2015-04-30 17:03 GMT+02:00 Maurizio Cimadamore <
maurizio.cimadamore at oracle.com>:
> For the records - I've added a comment in
>
> https://bugs.openjdk.java.net/browse/JDK-8039262
>
> Reporting in as much detail as possible the underlying cause of the
> performance regression.
>
> Maurizio
>
>
> On 29/04/15 18:38, Jan Lahoda wrote:
>
>> In 9, the Scope listeners are (AFAIK) only needed to update the "mark"
>> (so that the Types caches can detect obsolete entries). I think we may be
>> able to avoid the listeners at the cost of slowing down getMark somewhat
>> (getMark would ask the sub-scopes for their marks and sum the result). I'll
>> try.
>>
>> Jan
>>
>> On 29.4.2015 19:16, Maurizio Cimadamore wrote:
>>
>>> Found it.
>>>
>>> The big offender is the listeners field in the CompoundScope (which is a
>>> list).
>>>
>>> The test ends up creating huge listeners lists - probably because of
>>> very deep inheritance hierarchies.
>>>
>>> If I avoid adding stuff to the listeners field in the compound scope, I
>>> get back to a sane scenario:
>>>
>>> real 0m32.540s
>>> user 1m15.298s
>>> sys 0m1.126s
>>>
>>>
>>> And the profiled memory usage is much more under control.
>>>
>>> So, looks like we need a way to prevent these listeners list to
>>> overwhelm javac ;-)
>>>
>>> Maurizio
>>>
>>> On 29/04/15 17:51, Vicente-Arturo Romero-Zaldivar wrote:
>>>
>>>> On 04/29/2015 09:43 AM, Maurizio Cimadamore wrote:
>>>>
>>>>>
>>>>>
>>>>> On 29/04/15 17:01, Jan Lahoda wrote:
>>>>>
>>>>>> On 29.4.2015 16:06, Jacob Wieland wrote:
>>>>>>
>>>>>>> I have to admit, the reproducer is only a small part of the actual
>>>>>>> generated code. In my preliminary tests, it already sufficed to show
>>>>>>> a
>>>>>>> difference (also, the smaller code still worked with 32 bit while the
>>>>>>> whole code runs out of memory in all 32 bit versions which makes
>>>>>>> comparison much harder ;-) and which is why I need the 64 bit
>>>>>>> versions).
>>>>>>> If I test with the complete code which is much bigger, the results
>>>>>>> are
>>>>>>> as follows:
>>>>>>>
>>>>>>> jdk1.6u45(64bit) 2GB MaxMem - 1:30 minutes
>>>>>>> jdk1.7u75(64bit) 2GB MaxMem - > 6 min
>>>>>>> jdk1.8u31(64bit) 1GB MaxMem - > 15 min
>>>>>>> jdk1.8u31(64bit) 2GB MaxMem - > 10 min
>>>>>>> jdk1.8u31(64bit) 4GB MaxMem - 2:20 min (-source/-target 6 does not
>>>>>>> seem
>>>>>>> to have any effect)
>>>>>>>
>>>>>>> So, if you throw insane (in comparison with 1.6) amounts of memory at
>>>>>>> 1.7/1.8, it is only about a third as slow, but this still is
>>>>>>> unacceptable. I actually think it has to do with parallellization and
>>>>>>>
>>>>>>
>>>>>> When I was looking at JDK-8039262, a significant contributing factor
>>>>>> to the slowdown (with enough memory and -source/-target 6) appeared
>>>>>> to be Check.checkOverrideClashes - I believe this does checks that
>>>>>> were not properly implemented in 6, contributing to the difference
>>>>>> between 6 and 7 (which seems to be particularly visible for this
>>>>>> testcase). I was looking at the checks a few times, trying to write
>>>>>> them differently/faster while still performing the checks, but was
>>>>>> not successful in that yet, unfortunately.
>>>>>>
>>>>> I see the issue now - it is reproducible with the following memory
>>>>> parameter (at least in my machine):
>>>>>
>>>>> -J-Xmx768M
>>>>>
>>>>> This give around 20sec in JDK 6 and 10+ minutes in JDK 8.
>>>>>
>>>>> All the time seems to be spent in desugaring, most specifically in
>>>>> TransTypes.addBridges - it seems like that method calls
>>>>> Types.implementation a lot - so my theory was that the fact that
>>>>> javac consumes more memory, forces the GC to get rid of the cached
>>>>> entries in the implementation/members closure caches (since such
>>>>> entries are deliberately backed up by SoftReferences), which in turn
>>>>> completely trashes performances. I instrumented the code a bit and
>>>>> this is what I found:
>>>>>
>>>>> *) With -Xmx768M
>>>>>
>>>>> Impl cache misses = 3346926
>>>>> Members cache misses = 1042678
>>>>>
>>>>> real 7m0.335s
>>>>> user 25m51.517s
>>>>> sys 0m4.947s
>>>>>
>>>>>
>>>>> *) W/o -Xmx768M
>>>>>
>>>>> Impl cache misses = 3346839
>>>>> Members cache misses = 1042678
>>>>>
>>>>> real 0m32.377s
>>>>> user 1m25.881s
>>>>> sys 0m2.232s
>>>>>
>>>>> Long story short - cache misses do not play a factor in here - there
>>>>> are some minor differences, but nothing out of the ordinary and defo
>>>>> nothing that would explain a multi-minute slowdown! Any ideas?
>>>>>
>>>>
>>>> use flight recorder?
>>>>
>>>> Vicente
>>>>
>>>>
>>>>> Maurizio
>>>>>
>>>>>>
>>>>>> Jan
>>>>>>
>>>>>> garbage collection.
>>>>>>>
>>>>>>> 2015-04-29 15:12 GMT+02:00 Maurizio Cimadamore
>>>>>>> <maurizio.cimadamore at oracle.com
>>>>>>> <mailto:maurizio.cimadamore at oracle.com>>:
>>>>>>>
>>>>>>> On 29/04/15 12:44, Jacob Wieland wrote:
>>>>>>>
>>>>>>>> Hello Maurizio,
>>>>>>>>
>>>>>>>> are you sure that you used the 64bit versions of javac? I could
>>>>>>>> only observe the behavior with these.
>>>>>>>>
>>>>>>> Yep I'm on a Ubuntu x64 machine. It's actually pretty standard
>>>>>>> hardware too - i.e. intel i5 (two cores, but OS sees 4 because of
>>>>>>> hyper-threading).
>>>>>>>
>>>>>>>> Also, I just tried with jdk8u31-64b and it takes AGES (still
>>>>>>>> running after 17 minutes where the jdk6 was done after 2), top
>>>>>>>> shows 4GB VIRT memory use and 350 % load (on a 4core processor).
>>>>>>>>
>>>>>>> Maybe the reproducer you sent was incorrect?
>>>>>>>
>>>>>>> Maurizio
>>>>>>>
>>>>>>>
>>>>>>>> So, I don't think it was that problem.
>>>>>>>>
>>>>>>>> 2015-04-29 12:00 GMT+02:00 Maurizio Cimadamore
>>>>>>>> <maurizio.cimadamore at oracle.com
>>>>>>>> <mailto:maurizio.cimadamore at oracle.com>>:
>>>>>>>>
>>>>>>>> These are the numbers I'm getting:
>>>>>>>>
>>>>>>>> JDK 9 (b42)
>>>>>>>>
>>>>>>>> Note: generated_ttcn/TTCN3_CommonDefs.java uses or
>>>>>>>> overrides a
>>>>>>>> deprecated API.
>>>>>>>> Note: Recompile with -Xlint:deprecation for details.
>>>>>>>>
>>>>>>>> real 0m46.306s
>>>>>>>> user 2m17.489s
>>>>>>>> sys 0m2.166s
>>>>>>>>
>>>>>>>> JDK 8 (GA)
>>>>>>>>
>>>>>>>> Note: generated_ttcn/TTCN3_CommonDefs.java uses or
>>>>>>>> overrides a
>>>>>>>> deprecated API.
>>>>>>>> Note: Recompile with -Xlint:deprecation for details.
>>>>>>>>
>>>>>>>> real 6m58.748s
>>>>>>>> user 8m43.546s
>>>>>>>> sys 0m2.132s
>>>>>>>>
>>>>>>>> JDK 7 (1.7.0_79)
>>>>>>>>
>>>>>>>> Note: generated_ttcn/TTCN3_CommonDefs.java uses or
>>>>>>>> overrides a
>>>>>>>> deprecated API.
>>>>>>>> Note: Recompile with -Xlint:deprecation for details.
>>>>>>>>
>>>>>>>> real 0m28.341s
>>>>>>>> user 1m17.194s
>>>>>>>> sys 0m1.886s
>>>>>>>>
>>>>>>>>
>>>>>>>> As you can see there is a significant regression from JDK
>>>>>>>> 7 to
>>>>>>>> JDK 8 which was caused by
>>>>>>>>
>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8043253
>>>>>>>>
>>>>>>>> (some stack trace analysis revealed the familiar pattern).
>>>>>>>> This has also been fixed in JDK 8u20 (as stated in the bug
>>>>>>>> evaluation).
>>>>>>>>
>>>>>>>> So, while JDK 8u20/9 is slower than JDK 7 (at least on my
>>>>>>>> machine), the numbers are more or less in the same ballpark
>>>>>>>> and the huge regression that was visible in earlier JDK 8
>>>>>>>> releases has now been fixed.
>>>>>>>>
>>>>>>>> If you are still experiencing the problem - can you please
>>>>>>>> also submit the specific compiler versions you are using in
>>>>>>>> your benchmark?
>>>>>>>>
>>>>>>>> Maurizio
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 29/04/15 10:29, Maurizio Cimadamore wrote:
>>>>>>>>
>>>>>>>>> Hi Jacob,
>>>>>>>>> Stay assured - as we'll definitively look into this issue
>>>>>>>>> (I
>>>>>>>>> see it's already assigned to one of my colleagues).
>>>>>>>>>
>>>>>>>>> What I can say (w/o looking too much at the attached
>>>>>>>>> artifacts) is that in general, javac has no issue with
>>>>>>>>> compiling a lot of sources at once; at one point the build
>>>>>>>>> system was structured in such a way that all the JDK
>>>>>>>>> classes
>>>>>>>>> were compiled at once - and that (which is way more than
>>>>>>>>> your
>>>>>>>>> 187 sources - i.e. at least 10x that) took less than 20
>>>>>>>>> seconds. SO there must some specific pattern triggering
>>>>>>>>> that
>>>>>>>>> issue.
>>>>>>>>>
>>>>>>>>> Given that you say you have 187 input sources and 48K
>>>>>>>>> output
>>>>>>>>> classes, I'd say you are using inner classes a lot. I
>>>>>>>>> wonder
>>>>>>>>> if you are hitting this:
>>>>>>>>>
>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8000316
>>>>>>>>>
>>>>>>>>> Maurizio
>>>>>>>>>
>>>>>>>>> On 24/04/15 09:49, Jacob Wieland wrote:
>>>>>>>>>
>>>>>>>>>> Hello Folks,
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> I still have the open problem
>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8039262 that the
>>>>>>>>>> javac performance has degraded significantly from 1.6 to
>>>>>>>>>> 1.7
>>>>>>>>>> (and even worse to 1.8) in the 64bit versions. Since in
>>>>>>>>>> our
>>>>>>>>>> context, we are dealing with a lot of generated source1.4
>>>>>>>>>> Java input (either split into very large files with inner
>>>>>>>>>> classes or big packages with lots of smaller classes),
>>>>>>>>>> compiler performance is critical for our tool and this
>>>>>>>>>> degradation forces us to continue recommending to our
>>>>>>>>>> customers to use Java 1.6 for large projects (as is the
>>>>>>>>>> norm) as 1.7 and 1.8 are pretty much unusable in this
>>>>>>>>>> respect.
>>>>>>>>>>
>>>>>>>>>> Is anyone still working on this issue or is such
>>>>>>>>>> significant
>>>>>>>>>> performance degradation not a serious issue?
>>>>>>>>>>
>>>>>>>>>> My observations so far are:
>>>>>>>>>> - it gets worse the more class files are being
>>>>>>>>>> compiled/the
>>>>>>>>>> more files reside in the source path
>>>>>>>>>> - cpu usage goes through the roof over all available
>>>>>>>>>> kernels
>>>>>>>>>> - memory usage is much higher
>>>>>>>>>> - garbage collection seems to be much more active
>>>>>>>>>>
>>>>>>>>>> Using -proc:none alleviates the problem slightly for the
>>>>>>>>>> 1.7
>>>>>>>>>> version, but not for 1.8 (last we tested with
>>>>>>>>>> jdk1.8.0_31) where the performance difference is a factor
>>>>>>>>>> 5
>>>>>>>>>> or more!
>>>>>>>>>>
>>>>>>>>>> I can understand that a more advanced compiler has
>>>>>>>>>> capabilities that a previous version does not have and
>>>>>>>>>> thus
>>>>>>>>>> sometimes has
>>>>>>>>>> to do more work. But, it should still be possible
>>>>>>>>>> (especially if given the -source 1.4 or -source 1.5 option
>>>>>>>>>> as we do) to optimize it in such a way that unnecessary
>>>>>>>>>> checks for generics, overriding methods, closures,
>>>>>>>>>> annotations and other newer features can be turned off (if
>>>>>>>>>> they are to blame, which I actually doubt from my
>>>>>>>>>> observations).
>>>>>>>>>>
>>>>>>>>>> I would really appreciate your help in this regard and I
>>>>>>>>>> think everyone would benefit from any bugfix you can offer
>>>>>>>>>> for this.
>>>>>>>>>>
>>>>>>>>>> BR, Jacob Wieland
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> --
>>>>>>>>>> ------------------------------
>>>>>>>>>> -------------------------------------------
>>>>>>>>>> Dr. Jacob Wieland
>>>>>>>>>> Senior Software Engineer
>>>>>>>>>>
>>>>>>>>>> Testing Technologies IST GmbH
>>>>>>>>>> Michaelkirchstraße 17/18
>>>>>>>>>> 10179 Berlin, Germany
>>>>>>>>>>
>>>>>>>>>> Phone +49 30 726 19 19 34 Email
>>>>>>>>>> wieland at testingtech.com <mailto:stanca at testingtech.com>
>>>>>>>>>> Fax +49 30 726 19 19 20 Internet www.testingtech.com
>>>>>>>>>> <http://www.testingtech.com>
>>>>>>>>>> ---------------------------------------------------------------------------------------------------------------
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> -----------------------------------------------------------------------------------------------------------------
>>>>>>>>>>
>>>>>>>>>>
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>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> --
>>>>>>>> ------------------------------
>>>>>>>> -------------------------------------------
>>>>>>>> Dr. Jacob Wieland
>>>>>>>> Senior Software Engineer
>>>>>>>>
>>>>>>>> Testing Technologies IST GmbH
>>>>>>>> Michaelkirchstraße 17/18
>>>>>>>> 10179 Berlin, Germany
>>>>>>>>
>>>>>>>> Phone +49 30 726 19 19 34 Email wieland at testingtech.com
>>>>>>>> <mailto:stanca at testingtech.com>
>>>>>>>> Fax +49 30 726 19 19 20 Internet www.testingtech.com
>>>>>>>> <http://www.testingtech.com>
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>>>>>>>>
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>>>>>>>> Apr 21-23, 2015 | SAE Conference & Exhibition
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>>>>>>>> Apr 28-30, 2015 | iqnite
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>>>>>>>> Geschäftsführung: Theofanis Vassiliou-Gioles, Stephan Pietsch,
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>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> --
>>>>>>> ------------------------------
>>>>>>> -------------------------------------------
>>>>>>> Dr. Jacob Wieland
>>>>>>> Senior Software Engineer
>>>>>>>
>>>>>>> Testing Technologies IST GmbH
>>>>>>> Michaelkirchstraße 17/18
>>>>>>> 10179 Berlin, Germany
>>>>>>>
>>>>>>> Phone +49 30 726 19 19 34 Email wieland at testingtech.com
>>>>>>> <mailto:stanca at testingtech.com>
>>>>>>> Fax +49 30 726 19 19 20 Internet www.testingtech.com
>>>>>>> <http://www.testingtech.com>
>>>>>>> ---------------------------------------------------------------------------------------------------------------
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> -----------------------------------------------------------------------------------------------------------------
>>>>>>>
>>>>>>>
>>>>>>>
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>>>>>>> Deadline: May 30, 2015
>>>>>>> ucaat.etsi.org/2015/CallForPresentations.html
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>>>>>>>
>>>>>>> Apr 21-23, 2015 | SAE Conference & Exhibition
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>>>>>>> www.sae.org/congress/ <http://www.sae.org/congress/>
>>>>>>>
>>>>>>> Apr 28-30, 2015 | iqnite
>>>>>>> Dusseldorf, Germany
>>>>>>> www.iqnite-conferences.com/de/index.aspx
>>>>>>> <http://www.iqnite-conferences.com/de/index.aspx>
>>>>>>>
>>>>>>>
>>>>>>> -----------------------------------------------------------------------------------------------------------------
>>>>>>>
>>>>>>>
>>>>>>> Geschäftsführung: Theofanis Vassiliou-Gioles, Stephan Pietsch, Pete
>>>>>>> Nicholson Handelsregister HRB 77805 B, Amtsgericht Charlottenburg
>>>>>>> Ust ID
>>>>>>> Nr.: DE 813 143 070 This email may contain confidential and
>>>>>>> privileged
>>>>>>> material for the sole use of the intended recipient. Any review, use,
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>>>>>>> message.
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>
--
--
------------------------------
-------------------------------------------
Dr. Jacob Wieland
Senior Software Engineer
Testing Technologies IST GmbH
Michaelkirchstraße 17/18
10179 Berlin, Germany
Phone +49 30 726 19 19 34 Email wieland at testingtech.com
<stanca at testingtech.com>
Fax +49 30 726 19 19 20 Internet www.testingtech.com
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