[hibernate-dev] Optimizing reflection optimization
Steve Ebersole
steve at hibernate.org
Wed Jun 2 09:57:58 EDT 2010
Perhaps. We do in fact utilize setAccessible in the Hibernate code and
so when I did performance testing I did that as well as it most closely
matched our actual usage. Most likely it applies the checks "up front"
when setAccessible is called.
I'll take a look at the test and the numbers when i have a chance
(probably not till next week), but it is difficult to mimic all the
variables that come into play in different server environments (using
server versus client is only a small part).
On Wed, 2010-06-02 at 13:24 +0300, Кирилл Кленский wrote:
> Hi,
>
>
> I have done some tests that are more pure in that they do not involve
> the application logic.
>
>
> Java version: jdk1.6.0_19 32-bit
> Results include both client and server mode tests. Numbers represent
> 100 000 000 invocations time in milliseconds.
>
>
> The result format is the following:
> server_mode_test_time(server_mode_warmup_time) -
> client_mode_test_time(client_mode_warmup_time)
>
>
> ==========================
> Method access with direct call
> 24(4) - 69(70)
>
>
> Method access with reflection
> 815(3893) - 36 969(39162)
>
>
> Method access with reflection and setAccessible(true)
> 339(640) - 1297(1356)
>
>
> Method access with generated bytecode
> 3(2) - 646(666)
>
>
> Field access with reflection
> 40333(40016) - 40333(58800)
>
>
> Field access with reflection and setAccessible(true)
> 729(786) - 729(7696)
> ==========================
>
>
> I have the following thoughts after all:
>
>
> 1. Generated bytecode is comparable to direct access. Strange enough
> that it was even faster than direct access in server mode. Tests show
> that JVM seems to optimize reflection calls (warmup helps) but the
> difference between reflection and direct calls is huge.
> 2. Setting Method.setAccessible() and Field.setAccessible() to true
> helps to avoid security checks and increases the performance. May be
> this is the trick Bill is talking about?
> This potentially could be a relatively easy way to increase the
> performance especially if JVM is running in client mode (method
> invocation security checks take approx 10 times more time in client
> mode compared to server). In server mode the increase is relatively
> small for methods (several times) and huge for fields (approx 50
> times).
>
>
> I have attached the test code if somebody wants to compare results.
> Javassist 3.8.0.GA was used to generate bytecode and is required to
> build/run the test.
>
>
> Regards,
> Kirill Klenski
>
>
> 2010/5/27 Steve Ebersole <steve at hibernate.org>
> Perhaps it short circuits those copies and other overheads if
> no
> security manager is defined (ala as in my IDE). That would
> explain how
> I can see minimal improvement while Kirill sees a 4x
> improvement.
>
> Still rather confirm these numbers are accurate. Kirill?
>
>
> On Thu, 2010-05-27 at 10:12 -0400, Bill Burke wrote:
> > Carlo deWolfe found that one of the big perf problems with
> Java
> > reflection is that it is constantly doing security checks
> with the
> > security manager and every get/find request makes a copy of
> the
> > method/field objects. He had a hack for this, but you'll
> have to
> > consult him on what it is. The JBoss Reflections project
> might have it.
> >
> > I think once this hack is intiated, it is an improvement
> over Javassist.
> > If you think about it, Java VM has to build up this
> information anyways...
> >
> > Steve Ebersole wrote:
> > > I ran this same exact comparison before and I seem to
> recall much
> > > different results. Unfortunately I no longer have that
> code. This was
> > > part of
> > >
> http://opensource.atlassian.com/projects/hibernate/browse/HHH-227
> > >
> > > Can you make sure you "prime" or "warm up" the jvm before
> you start
> > > taking measurements?
> > >
> > > On Thu, 2010-05-27 at 15:39 +0300, Кирилл Кленский wrote:
> > >> Hi,
> > >>
> > >> My measurements have indicated that there is a
> performance gain. I have
> > >> measured the time spent in setPropertyValues and
> getPropertyValues.
> > >> The optimized version was 4 times faster in these methods
> giving an
> > >> estimated application performance increase of about 3%.
> > >> Optimizing getPropertyValue and setPropertyValue could
> give 1.5% more
> > >> according to our rough calculations.
> > >>
> > >> Kirill
> > >>
> > >> 26 мая 2010 г. 23:53 пользователь Emmanuel Bernard
> > >> <emmanuel at hibernate.org>написал:
> > >>
> > >>> Hi,
> > >>> Have you noticed a perf difference in your application
> with and without the
> > >>> patch?
> > >>> I am wondering if modern VMs have catched up with what
> Javassist does.
> > >>>
> > >>> On 26 mai 2010, at 18:29, Кирилл Кленский wrote:
> > >>>
> > >>>> 1. I have noticed that
> > >>>>
> org.hibernate.bytecode.javassist.BulkAccessorFactory.findAccessors(...)
> > >>> is
> > >>>> searching for accessor methods in the optimized entity
> class only. This
> > >>>> means that the methods from the superclasses are not
> visible during
> > >>>> BulkAccessor creation unless overridden by child
> classes. By enhancing
> > >>> the
> > >>>> algorithm to search down the inheritance tree we could
> avoid creation of
> > >>>> redundant methods which increase the code verbosity a
> lot. In our case
> > >>>> almost all the entities are inherited from the base
> classes having the
> > >>>> common entity properties defined, so the reflection
> optimization does not
> > >>>> work for any of them until we override the inherited
> methods in all the
> > >>>> child classes. The implementation is trivial, but I
> have got a ready
> > >>>> prototype if anybody is interested.
> > >>>
> > >> _______________________________________________
> > >> hibernate-dev mailing list
> > >> hibernate-dev at lists.jboss.org
> > >> https://lists.jboss.org/mailman/listinfo/hibernate-dev
> > >
> > >
> >
>
>
> --
>
>
> Steve Ebersole <steve at hibernate.org>
> http://hibernate.org
>
>
>
>
--
Steve Ebersole <steve at hibernate.org>
http://hibernate.org
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