ParNew 4x slower under 1.7 vs 1.6?

[Bernd Eckenfels]

Hello,

since the different workload from jaxb was very visible in your par-new  
times, I wonder if you can also research a bit in that direction: have  
been the average objectsize small or larger, has the object graph beeing  
deeper or more gc roots.

I think having a heap dump of both jaxb versions with the same VM would be  
a good start to compare? (I am not sure if there are statistic tools for  
the above numbers, but I guess the class histogram can give a good first  
answer)

Greetings
Bernd


Am 13.09.2013, 17:53 Uhr, schrieb Andrew Mulholland  
<anmulholland at expedia.com>:

> Hi Jon
>
> Many thanks for your help in this.
>
> To close off this thread, Jon provided help to us in investigating this
> issue.
>
> We conducted some tests which demonstrated it wasn't changes in the VM
> causing our slowdown. (Jon directed me to create a sort of hybrid JVM by
> copying the libjvm.so from 1.7.0_25 into a 1.6.0_43 JDK).
>
> We spent out time looking into what was different between 6 and 7 outside
> of the JVM... and through a process of elimination identified that the
> change in JAXB version from 2.1 to 2.2 which came with JDK7 was causing
> the change in performance.
>
> By loading the jaxb 2.1 jars into our app, rather than relying on the
> version provided by the JDK, we now see a similar level of performance
> under JDK7 as we did under JDK6.
>
> (also for those interested by loading the jaxb 2.2 jars into our app, we
> see the slowdown under JDK6 too).
>
>
> We're investigating what the differences are between JAXB 2.1 and 2.2 and
> how we use it, as suspect it could be (our) misuse of the library which  
> is
> to blame here!
>
> Thanks
>
>
> Andrew
>
>
> Andrew Mulholland
> Operations Architect
> Expedia Affiliate Network
> p: +44 (0)20 7019 2927 | m: +44 (0)77 1585 4475
> e: anmulholland at expedia.com
>
>
>
> On 8/12/13 10:57 AM, "Andrew Mulholland" <anmulholland at expedia.com>  
> wrote:
>
>> Hi Jon
>>
>>
>> On 8/12/13 5:50 AM, "Jon Masamitsu" <jon.masamitsu at oracle.com> wrote:
>>
>>>
>>> I saw your response to  Bernd where you verified
>>> the number of GC threads that you are using but the
>>> amount of parallelism your getting still doesn't seem to
>>> be right.  See below.
>>
>>
>> Thanks - data below as requested:
>>
>>>
>>> , 0.0989930 secs] [Times: user=0.46 sys=0.02, real=0.10 secs]
>>>
>>>
>>>
>>> About a 4 times speed up here (user / real ~ 4.6)
>>>
>>
>> For JVM 1.6.0_43:
>>
>> 90% of ParNew Gcs had parallelism of at least: 5.17
>> 75% of ParNew Gcs had parallelism of at least: 5.83
>> 50% of ParNew Gcs had parallelism of at least: 6.71
>> 25% of ParNew Gcs had parallelism of at least 7.66
>> 10% of ParNew Gcs had parallelism of at least 8.5
>>
>> Average parallelism for ParNew Gs: 6.75 (stdev 1.21)
>> Max Parallelism for ParNew GCs: 9
>>
>>
>>>
>>> , 0.4156130 secs] [Times: user=0.65 sys=0.02, real=0.42 secs]
>>>
>>>
>>> Only about a 1.5 times speed up here (user / real ~1.5).
>>
>> For JVM 1.7.0_25:
>>
>> 90% of ParNew Gcs had parallelism of at least 1.53
>>
>> 75% of ParNew Gcs had parallelism of at least 1.63
>> 50% of ParNew Gcs had parallelism of at least 2
>> 25% of ParNew Gcs had parallelism of at least: 2.72
>> 10% of ParNew Gcs had parallelism of at least: 5.32
>>
>> Average parallelism for ParNew GCs: 2.58 (stdev 1.51)
>>
>> Max Parallelism for ParNew GCs: 8.6
>>
>>
>>
>>
>>
>>>
>>> Can you check some other entries and verify that the amount of
>>> parallelism your seeing on 1.7 is only 1.5.
>>>
>>
>>
>>> From the above it seems that we do get higher than 1.5.. With jvm 1.7 -
>> but it is consistently significantly lower than on jvm 1.6
>>
>> Thanks
>>
>>
>> Andrew
>>
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