ParNew 4x slower under 1.7 vs 1.6?

[Andrew Mulholland]

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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