[hibernate-dev] Optimizing reflection optimization
Кирилл Кленский
kirill.klenski at gmail.com
Wed Jun 2 10:44:14 EDT 2010
"We do in fact utilize setAccessible in the Hibernate code"
Yes, but if I am not mistaken only if the method/field is not public. From
code: !ReflectHelper.isPublic(theClass, method) )
method.setAccessible(true);
We could increase performance easily if we call setAccessible even for
public methods - we get rid of costly security checks.
Kirill
2 июня 2010 г. 16:57 пользователь Steve Ebersole <steve at hibernate.org>написал:
> 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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