Groups > comp.lang.java.programmer > #15599

Re: Controlling the Garbage Collector

From	Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at>
Newsgroups	comp.lang.java.programmer
Subject	Re: Controlling the Garbage Collector
Date	2012-06-26 16:26 +0000
Organization	A noiseless patient Spider
Message-ID	<slrnjujol5.u9l.avl@gamma.logic.tuwien.ac.at> (permalink)
References	(10 earlier) <slrnjuh6bd.u9l.avl@gamma.logic.tuwien.ac.at> <jsa838$vih$1@dont-email.me> <a4rpnjForkU1@mid.individual.net> <slrnjujaih.u9l.avl@gamma.logic.tuwien.ac.at> <5d156697-1477-49c1-a098-f7bfa76783b4@googlegroups.com>

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Robert Klemme <shortcutter@googlemail.com> wrote:
> On Tuesday, June 26, 2012 2:25:53 PM UTC+2, Andreas Leitgeb wrote:
>> Robert Klemme <shortcutter@googlemail.com> wrote:
>> > Thank you for the elaboration, Eric and Andreas!  I think a non uniform 
>> > object memory model (e.g. some GCed, some manually managed) cannot get 
>> > rid of the GC overhead even for the manual kind as long as it is allowed 
>> > to have references between the different kinds of objects.
>> It is no problem for GC'ed objects to be referenced from manually
>> managed objects.

> I think it is.  The point in separating object kinds is to reduce the
> number of objects GC has to look at in order to avoid looking at long
> lived old objects over and over again.

Oh, seems I got the motivation wrong, then.  If that was your point,
then obviously my essay didn't address that.  My motivation was having
some large objects, whose memory could be explicitly freed, as soon as
the memory was no longer needed in the program.

>> [ManualReference to deal with possibly dangling pointers sanely]
> Basically that's the same situation we have with WeakReference now and
> as consequence you need to check the reference for null on every access.

That's not the point. Seeing a null in a manual reference would
happen only from a Bug: it indicates that you freed an object that
still had refs on it, which shouldn't have happened in the first place.
Theoretically, a hypothetical JVM might even throw a different exception
for this case, such as a DanglingPointerException to be used only for
debugging:-)

I've snipped most of your comments, as I think they are just following
from the misunderstanding... (lock, refcount,...)

>> Gist: I think it *could* be done, but it would surely require some
>>  deep changes in Java, that are not justified by any so far identified
>>  advantage.
> I don't even think there is an advantage.

Well, so do I.  It was still fun, thinking about it.

Thread

Recommendations for Lightweight Threading? "Aaron W. Hsu" <arcfide@sacrideo.us> - 2012-06-15 17:33 -0500
  Re: Recommendations for Lightweight Threading? markspace <-@.> - 2012-06-15 15:55 -0700
    Re: Recommendations for Lightweight Threading? "Aaron W. Hsu" <arcfide@sacrideo.us> - 2012-06-15 18:12 -0500
      Re: Recommendations for Lightweight Threading? markspace <-@.> - 2012-06-15 16:31 -0700
        Re: Recommendations for Lightweight Threading? "Aaron W. Hsu" <arcfide@sacrideo.us> - 2012-06-15 20:00 -0500
        Re: Recommendations for Lightweight Threading? Robert Klemme <shortcutter@googlemail.com> - 2012-06-16 14:39 +0200
          Re: Recommendations for Lightweight Threading? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-06-16 12:13 -0700
      Re: Recommendations for Lightweight Threading? Roedy Green <see_website@mindprod.com.invalid> - 2012-06-16 00:57 -0700
  Re: Recommendations for Lightweight Threading? Lew <lewbloch@gmail.com> - 2012-06-15 15:57 -0700
    Re: Recommendations for Lightweight Threading? "Aaron W. Hsu" <arcfide@sacrideo.us> - 2012-06-15 18:12 -0500
  Re: Recommendations for Lightweight Threading? Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-15 20:19 -0400
    Re: Recommendations for Lightweight Threading? "Aaron W. Hsu" <arcfide@sacrideo.us> - 2012-06-15 19:59 -0500
      Re: Recommendations for Lightweight Threading? Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-15 21:37 -0400
        Controlling the Garbage Collector "Aaron W. Hsu" <arcfide@sacrideo.us> - 2012-06-16 11:51 -0500
          Re: Controlling the Garbage Collector Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-16 14:24 -0400
            Re: Controlling the Garbage Collector markspace <-@.> - 2012-06-16 12:24 -0700
              Re: Controlling the Garbage Collector Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-06-16 13:14 -0700
                Re: Controlling the Garbage Collector Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-16 16:35 -0400
                Re: Controlling the Garbage Collector "Aaron W. Hsu" <arcfide@sacrideo.us> - 2012-06-16 19:43 -0500
                Re: Controlling the Garbage Collector Wanja Gayk <brixomatic@yahoo.com> - 2012-06-23 13:36 +0200
                Re: Controlling the Garbage Collector Robert Klemme <shortcutter@googlemail.com> - 2012-06-23 15:39 +0200
                Re: Controlling the Garbage Collector markspace <-@.> - 2012-06-16 14:34 -0700
          Re: Controlling the Garbage Collector Robert Klemme <shortcutter@googlemail.com> - 2012-06-18 04:32 -0700
            Re: Controlling the Garbage Collector Roedy Green <see_website@mindprod.com.invalid> - 2012-06-24 14:31 -0700
          Re: Controlling the Garbage Collector Arne Vajhøj <arne@vajhoej.dk> - 2012-06-20 21:19 -0400
            Re: Controlling the Garbage Collector "Aaron W. Hsu" <arcfide@sacrideo.us> - 2012-06-21 13:24 -0500
              Re: Controlling the Garbage Collector Lew <lewbloch@gmail.com> - 2012-06-21 11:37 -0700
                Re: Controlling the Garbage Collector Fred Greer <fggreer@nospam.invalid> - 2012-06-21 21:20 +0000
              Re: Controlling the Garbage Collector Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-21 15:24 -0400
              Re: Controlling the Garbage Collector Robert Klemme <shortcutter@googlemail.com> - 2012-06-21 23:46 +0200
                Re: Controlling the Garbage Collector Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2012-06-25 15:28 +0300
                Re: Controlling the Garbage Collector Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-25 09:05 -0400
                Re: Controlling the Garbage Collector Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2012-06-25 17:01 +0000
                Re: Controlling the Garbage Collector Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-25 13:45 -0400
                Re: Controlling the Garbage Collector Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-25 13:49 -0400
                Re: Controlling the Garbage Collector Robert Klemme <shortcutter@googlemail.com> - 2012-06-25 20:41 +0200
                Re: Controlling the Garbage Collector Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2012-06-26 12:25 +0000
                Re: Controlling the Garbage Collector Robert Klemme <shortcutter@googlemail.com> - 2012-06-26 06:46 -0700
                Re: Controlling the Garbage Collector Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2012-06-26 16:26 +0000
                Re: Controlling the Garbage Collector Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-26 13:07 -0400
                Re: Controlling the Garbage Collector Robert Klemme <shortcutter@googlemail.com> - 2012-06-26 22:28 +0200
                Re: Controlling the Garbage Collector Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2012-06-26 23:49 +0000
                Re: Controlling the Garbage Collector Lew <lewbloch@gmail.com> - 2012-06-26 18:20 -0700
                Re: Controlling the Garbage Collector Highway to Hell <HtH49439112@gmail.com> - 2012-06-26 21:52 -0400
                Re: Controlling the Garbage Collector Gene Wirchenko <genew@ocis.net> - 2012-06-26 20:01 -0700
                Re: Controlling the Garbage Collector Highway to Hell <HtH49439112@gmail.com> - 2012-06-26 23:23 -0400
                Re: Controlling the Garbage Collector Gene Wirchenko <genew@ocis.net> - 2012-06-27 09:05 -0700
                Re: Controlling the Garbage Collector Martin Gregorie <martin@address-in-sig.invalid> - 2012-06-27 20:15 +0000
                Re: Controlling the Garbage Collector Gene Wirchenko <genew@ocis.net> - 2012-06-27 13:52 -0700
                Re: Controlling the Garbage Collector Lew <lewbloch@gmail.com> - 2012-06-27 13:41 -0700
                Re: Controlling the Garbage Collector Gene Wirchenko <genew@ocis.net> - 2012-06-27 19:02 -0700
                Re: Controlling the Garbage Collector Martin Gregorie <martin@address-in-sig.invalid> - 2012-06-28 21:45 +0000
                Re: [OT] Driver's license restrictions (Was: Controlling the Garbage Collector) Lew <lewbloch@gmail.com> - 2012-06-28 15:16 -0700
                Re: [OT] Driver's license restrictions (Was: Controlling the Garbage Collector) Martin Gregorie <martin@address-in-sig.invalid> - 2012-06-29 02:10 +0000
                Re: [OT] Driver's license restrictions (Was: Controlling the Garbage Collector) Gene Wirchenko <genew@ocis.net> - 2012-06-28 19:57 -0700
                Re: [OT] Driver's license restrictions glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-06-29 04:06 +0000
                Re: [OT] Driver's license restrictions Tim Slattery <Slattery_T@bls.gov> - 2012-06-29 08:35 -0400
                Re: [OT] Driver's license restrictions (Was: Controlling the Garbage Collector) Tim Slattery <Slattery_T@bls.gov> - 2012-06-29 08:33 -0400
                Re: Controlling the Garbage Collector Tim Slattery <Slattery_T@bls.gov> - 2012-06-29 08:30 -0400
                Re: Controlling the Garbage Collector Martin Gregorie <martin@address-in-sig.invalid> - 2012-06-29 23:04 +0000
                Re: Controlling the Garbage Collector Highway to Hell <HtH49439112@gmail.com> - 2012-06-27 16:53 -0400
                Re: Controlling the Garbage Collector Leif Roar Moldskred <leifm@dimnakorr.com> - 2012-06-27 11:32 -0500
                Re: Controlling the Garbage Collector Highway to Hell <HtH49439112@gmail.com> - 2012-06-27 16:54 -0400
                Re: Controlling the Garbage Collector Lew <lewbloch@gmail.com> - 2012-06-27 11:45 -0700
                Re: Controlling the Garbage Collector Highway to Hell <HtH49439112@gmail.com> - 2012-06-27 16:55 -0400
                Re: Controlling the Garbage Collector glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-06-27 02:06 +0000
                Re: Controlling the Garbage Collector Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2012-06-27 16:34 +0000
                Re: Controlling the Garbage Collector Leif Roar Moldskred <leifm@dimnakorr.com> - 2012-06-27 11:45 -0500
                Re: Controlling the Garbage Collector Wanja Gayk <brixomatic@yahoo.com> - 2012-07-02 11:21 +0200
                Re: Controlling the Garbage Collector Lew <lewbloch@gmail.com> - 2012-06-26 13:52 -0700
                Re: Controlling the Garbage Collector Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2012-06-26 23:40 +0000
                Re: Controlling the Garbage Collector Lew <lewbloch@gmail.com> - 2012-06-26 16:48 -0700
              Re: Controlling the Garbage Collector markspace <-@.> - 2012-06-21 15:15 -0700
                Re: Controlling the Garbage Collector Lew <lewbloch@gmail.com> - 2012-06-21 15:33 -0700
                Re: Controlling the Garbage Collector "Aaron W. Hsu" <arcfide@sacrideo.us> - 2012-06-21 21:24 -0500
              Re: Controlling the Garbage Collector markspace <-@.> - 2012-06-21 15:23 -0700
        Re: Recommendations for Lightweight Threading? Wanja Gayk <brixomatic@yahoo.com> - 2012-06-17 15:49 +0200
    Re: Recommendations for Lightweight Threading? Roedy Green <see_website@mindprod.com.invalid> - 2012-06-16 01:00 -0700
      Re: Recommendations for Lightweight Threading? Roedy Green <see_website@mindprod.com.invalid> - 2012-06-16 01:04 -0700
  Re: Recommendations for Lightweight Threading? Wanja Gayk <brixomatic@yahoo.com> - 2012-06-16 04:03 +0200
  Re: Recommendations for Lightweight Threading? Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2012-06-15 22:27 -0700
    Re: Recommendations for Lightweight Threading? Robert Klemme <shortcutter@googlemail.com> - 2012-06-16 14:39 +0200
      Re: Recommendations for Lightweight Threading? Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2012-06-18 19:37 -0700
        Re: Recommendations for Lightweight Threading? Robert Klemme <shortcutter@googlemail.com> - 2012-06-19 07:46 -0700

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