Groups > comp.lang.java.programmer > #15493

Re: Controlling the Garbage Collector

From	Eric Sosman <esosman@ieee-dot-org.invalid>
Newsgroups	comp.lang.java.programmer
Subject	Re: Controlling the Garbage Collector
Date	2012-06-21 15:24 -0400
Organization	A noiseless patient Spider
Message-ID	<jrvsds$bls$1@dont-email.me> (permalink)
References	(2 earlier) <6KSdnTwztJvtR0bSnZ2dnUVZ_t-dnZ2d@giganews.com> <jrgo11$3t6$1@dont-email.me> <_JmdnUu_Z-scJEHSnZ2dnUVZ_t6dnZ2d@giganews.com> <4fe27687$0$281$14726298@news.sunsite.dk> <K9mdnVvXpcl4-37SnZ2dnUVZ_q6dnZ2d@giganews.com>

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On 6/21/2012 2:24 PM, Aaron W. Hsu wrote:
> [...]
> On the other side, there are times when I know that I am going to be
> doing a number of very small, little allocations all in a row, and I do
> not want the GC to run during this tight loop, because it will cause a
> noticeable hit. I would rather delay the collector, consuming more memory
> until the end when I can explicitly trigger the collector at that point.

     Sounds like you might be better off collecting first, when there
are fewer objects to be discovered and analyzed.  Also, since you've
said you're not speaking of real-time applications, I don't see why
you should be concerned about the precise timing of the "hit:" Before,
after, during, what difference does it make?  (If you're worried about
GC roiling the caches, please provide actual measurements.)

> Or, I may know that some structure is going to be extremely long lived
> and I need to keep it out of the collector entirely.

     Generational collectors do a pretty good imitation of this.  It's
not perfect because it takes time for the GC to discover what's long-
lived and what's not, but it's pretty effective.  Also, it has the
huge advantage of always being right; few programmers can match that
accuracy.  (See also "memory leak.")

> Finally, there are times when I want to do a large bulk allocation
> outside of the collector, and then selectively move certain things into
> the collected space, but still have a checked, high-level way of
> accessing data structures in the uncollected space.

     JNI, if you simply must.

> Now, all of these are corner cases to me because you can get by without
> them in most situations, unless you are trying to eek out all of the
> performance you can from your system.

     "Eek" is right ...

-- 
Eric Sosman
esosman@ieee-dot-org.invalid

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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