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From "Alexei Fedotov" <alexei.fedo...@gmail.com>
Subject Re: [VM] On-demand class library parsing is ready to commit
Date Fri, 26 Dec 2008 08:03:07 GMT
Xiao-Feng,
Continuing with the server example could you please give me a hint where
decision to load swing.jar or not is taken in the patch? My initial
perception was that the list of what to load was hardcoded and was not
constructed dynamically depending on application.

Thanks.


On Fri, Dec 26, 2008 at 4:14 AM, Xiao-Feng Li <xiaofeng.li@gmail.com> wrote:

> On Fri, Dec 26, 2008 at 12:49 AM, Alexei Fedotov
> <alexei.fedotov@gmail.com> wrote:
> > Aleksey,
> > I like your conclusion.
> >
> > Wenlong,
> > I'm trying to understand the real life value of the "abstract" startup
> > time metric you've suggested. Does Harmony with your patch load
> > swing.jar for a server application? Do I understand that loading
> > happens, though it happens later compared to VM without your patch? I
> > believe that the proper design of delayed loading should answer "no"
> > to this question.
>
> I checked the patch, and I found the answer is indeed "No" as you expected.
>
> Thanks,
> xiaofeng
>
> > In other words, I appreciate if you describe which real use cases are
> > improved by this patch.
> > Thanks!
>
> > On Thu, Dec 25, 2008 at 7:29 PM, Aleksey Shipilev
> > <aleksey.shipilev@gmail.com> wrote:
> >> Ok, here's the catch.
> >>
> >> bootclasspath.properties is the SortedSet<JARfile>, which enumerates
> >> the JARs available for bootclassloader. The set of such the JARs is
> >> really stable because modular decomposition of classlib is stable.
> >> That's why nobody bothers with automatic generation of it: it only
> >> should be updated when new JAR file arrives.
> >> Modulelibrarymapping.properties is different on this point, it's the
> >> Map<PackageName,JARfile>, which should be updated each time the new
> >> *package* is introduced. I'm not talking about java.* packages
> >> (they're standardized), rather about org.apache.harmony.*.
> >>
> >> Automatic generation of this property file gives two advantages:
> >>  1. Error-prone. Prevent yourself from hand-messing with mapping and
> >> getting spurious ClassNotFoundException. BTW, what's the behaviour in
> >> case the mapping is wrong?
> >>  2. "Researchful". There're lot of guys around who enjoys the
> >> modularity of Harmony classlib and eventually they might want to split
> >> the packages even deeper, into smaller pieces. Then automatic
> >> generation would enable them to quickly roll-in and experiment with
> >> different package layouts and their impact on performance. They could
> >> use ordinary bootclasspath.properties, but your feature wouldn't be
> >> used by them then ;)
> >>
> >> That's merely a housekeeping procedure. I believe that anything which
> >> could be done more than once, eventually would be done more than once.
> >> Hence it should be automated. You say that the file was generated from
> >> manifests of JARs, so is it hard to just tie the same tool into DRLVM
> >> build process?
> >>
> >> As for DRLVM-specific, my opinion that this is because the patch:
> >>  a. breaks the compatibility of classlib (you change
> >> bootclasspath.properties, right?) with other VMs.
> >>  b. treated in DRLVM classloader only.
> >>
> >> Of course eventually this feature might be used by others, but IMO we
> >> should be careful about other guys who use the same classlib. I'd
> >> rather wait for some incubation on DRLVM side first.
> >>
> >> Thanks,
> >> Aleksey.
> >>
> >> On Thu, Dec 25, 2008 at 6:18 PM, Wenlong Li <wenlong@gmail.com> wrote:
> >>> I see. In fact, my file doesn't need track change at the class
> >>> granularity. Instead, it only needs know package info provided in the
> >>> manifest file.  When class is added to a library, do we need change
> >>> the manifest as well?
> >>>
> >>> btw, I guess there is a mis-understanding: my modulelibrarymapping
> >>> file only records package info provided by manfiest in each module. It
> >>> doesn't relate to each class.
> >>>
> >>> thx,
> >>> Wenlong
> >>>
> >>> On Thu, Dec 25, 2008 at 10:55 PM, Pavel Pervov <pmcfirst@gmail.com>
> wrote:
> >>>> Classes are added to class library from time to time. I'm not sure how
> >>>> it can be possible to track these changes manually.
> >>>>
> >>>> WBR,
> >>>>    Pavel.
> >>>>
> >>>>
> >>>> On Thu, Dec 25, 2008 at 5:09 PM, Wenlong Li <wenlong@gmail.com>
> wrote:
> >>>>> Sorry, one more question: bootclasspath.properties is classlib
> >>>>> specific file, why we could not make a vm specific file manually?
> Just
> >>>>> curious to know the possible reason. :)
> >>>>>
> >>>>> thx,
> >>>>> Wenlong
> >>>>>
> >>>>> On Thu, Dec 25, 2008 at 10:00 PM, Pavel Pervov <pmcfirst@gmail.com>
> wrote:
> >>>>>> If this would be VM-side automatically produced configuration
> file...
> >>>>>>
> >>>>>> WBR,
> >>>>>>    Pavel.
> >>>>>>
> >>>>>> On Thu, Dec 25, 2008 at 4:58 PM, Wenlong Li <wenlong@gmail.com>
> wrote:
> >>>>>>> btw, because adding new module is rare case, manually modifying
the
> >>>>>>> bootclasspath.properties is not an issue?
> >>>>>>>
> >>>>>>> If so, can I conclude adding another property file with
same update
> >>>>>>> frequency as bootclasspath would be fine as well?
> >>>>>>>
> >>>>>>> Pls kindly correct me if my understanding is wrong.
> >>>>>>>
> >>>>>>> On Thu, Dec 25, 2008 at 9:05 PM, Pavel Pervov <pmcfirst@gmail.com>
> wrote:
> >>>>>>>> Wenlong,
> >>>>>>>>
> >>>>>>>> Note, that bootclasspath.properties is only changed
on adding new
> >>>>>>>> module. This is pretty rare occasion, I believe.
> >>>>>>>>
> >>>>>>>> WBR,
> >>>>>>>>    Pavel.
> >>>>>>>>
> >>>>>>>> On Thu, Dec 25, 2008 at 3:48 PM, Wenlong Li <wenlong@gmail.com>
> wrote:
> >>>>>>>>> Thx for your advice. Alexey.
> >>>>>>>>>
> >>>>>>>>> Here I have one question: do you know how the
> bootclasspath.properties
> >>>>>>>>> is maintained, manually or automatically?
> >>>>>>>>>
> >>>>>>>>> Another comment is I would like to treat the patch
as DRLVM
> specific
> >>>>>>>>> optimization, e.g., it targets for improving VM
creation time. So
> that
> >>>>>>>>> is possible to move all updates to DRLVM part to
eliminate
> potential
> >>>>>>>>> modularity and compatibility problem.
> >>>>>>>>>
> >>>>>>>>> thx,
> >>>>>>>>> Wenlong
> >>>>>>>>>
> >>>>>>>>> On Thu, Dec 25, 2008 at 5:32 PM, Aleksey Shipilev
> >>>>>>>>> <aleksey.shipilev@gmail.com> wrote:
> >>>>>>>>>> Hi, Wenlong.
> >>>>>>>>>>
> >>>>>>>>>> On Thu, Dec 25, 2008 at 11:49 AM, Wenlong Li
<wenlong@gmail.com>
> wrote:
> >>>>>>>>>>> btw, Alexey, Let's go back to discuss whether
there is a need
> to
> >>>>>>>>>>> include this feature in Harmony, given 17%
performance gain in
> Linux
> >>>>>>>>>>> when using your methodology. For windows
test, I will double
> check the
> >>>>>>>>>>> backgroud process as you pointed out.
> >>>>>>>>>>
> >>>>>>>>>> My opinion was already expressed after I had
finished the tests
> from
> >>>>>>>>>> my side: the boost can be achieved in specific
conditions, so
> whether
> >>>>>>>>>> it's worth including into Harmony really depends
on how much
> mess the
> >>>>>>>>>> patch would introduce besides the "performance
boost". From what
> I
> >>>>>>>>>> see, the patch obliges the maintainer to maintain
the correct
> mapping
> >>>>>>>>>> between jars and Java packages. This new feature
is also spread
> >>>>>>>>>> between Classlib and VM, but it seems like DRLVM
specific. In
> this
> >>>>>>>>>> case I would rather stay without the patch.
> >>>>>>>>>>
> >>>>>>>>>> Personally (if I'll be committer) I would accept
the patch with
> two
> >>>>>>>>>> serious modifications:
> >>>>>>>>>>  1. Stay within DRLVM, do not introduce this
feature into
> Classlib,
> >>>>>>>>>> get the thing tested and evolved on DRLVM side.
Otherwise it
> might
> >>>>>>>>>> break the compatibility with other VMs.
> >>>>>>>>>>  2. Make the mapping generated automatically
(during build
> process?)
> >>>>>>>>>> to free the burden for maintainers.
> >>>>>>>>>>
> >>>>>>>>>> Thanks,
> >>>>>>>>>> Aleksey.
> >>>>>>>>>>
> >>>>>>>>>
> >>>>>>>>
> >>>>>>>
> >>>>>>
> >>>>>
> >>>>
> >>>
> >>
> >
> >
> >
> > --
> > С уважением,
> > Алексей Федотов,
> > ЗАО «Телеком Экспресс»
> >
>
>
>
> --
> http://xiao-feng.blogspot.com
>



-- 
С уважением,
Алексей Федотов,
ЗАО «Телеком Экспресс»
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