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Groups > comp.lang.forth > #50881
| From | anton@mips.complang.tuwien.ac.at (Anton Ertl) |
|---|---|
| Newsgroups | comp.lang.forth |
| Subject | Re: Implementing lisp in Forth. Chapter 4. |
| Date | 2016-09-12 09:43 +0000 |
| Organization | Institut fuer Computersprachen, Technische Universitaet Wien |
| Message-ID | <2016Sep12.114311@mips.complang.tuwien.ac.at> (permalink) |
| References | (2 earlier) <nq7rv3$lhl$1@cherry.spenarnc.xs4all.nl> <87twdznhhz.fsf@jester.gateway.pace.com> <nqbhus$4fp$1@cherry.spenarnc.xs4all.nl> <87fupfo6xl.fsf@jester.gateway.pace.com> <7d7764ab-19e2-44f2-a0e1-66f92798b03f@googlegroups.com> |
lawrencedo99@gmail.com writes:
>On Monday, September 5, 2016 at 6:28:59 AM UTC+12, Paul Rubin wrote:
>> ... ALLOC notices if you're running low on memory, and performs a GC if y=
>ou
>> are.
>
>How does it decide when you are =E2=80=9Crunning low on memory=E2=80=9D?
This is actually documented pretty exhaustively in the manual:
|Tuning
|
|gc.fs generally uses only a part of the memory it manages. This policy
|allows you to give it a huge amount of memory to manage, as
|preparation for the worst case, without consuming that much real (and,
|for good OSes, even virtual) memory before it is necessary.
|
|The amount of memory actually used is determined in the following way:
|
|memory= (a * livemem / b) + c
|
|Where livemem is the amount of memory in live objects after the last
|garbage collection, and a, b, and c are tunable parameters. By
|default, a/b is 3, and c is 256KB.
|
|You can tune these parameters for your application: You can reduce the
|memory, at the cost of a higher number of garbage collections, or you
|can increase it to reduce the number of garbage collections. Note that
|if you reduce memory too much (to less than about 2*livemem), the
|number of garbage collections rises extremely. And if a
|garbage-collection does not free an appropriate memory chunk, alloc
|will grab more memory regardless of the limit.
|
|The following code sequence demonstrates the adjustment of parameters
|by resetting them to their default values:
|
|also garbage-collector
|3 1 ( a b ) size-factor 2!
|256 1024 * ( c ) grain/ size-offset !
|set-current-limit
|previous
You also have to tell gc.fs how much maximum memory it should use; it
will allocate that much (plus 1/32 of that) from the start, but will
write to only the part of it that the "memory" above specifies; so
only that much physical memory (and, with overcommit, that much
virtual memory) is really consumed; in other words, if you have an OS
with overcommit, you can make the maximum memory big, e.g., the RAM
size, and if the amount of live memory stays small, the amount of used
memory will also stay relatively small.
> Do=
>es it limit your heap size, like Java does?
I have no idea how Java does it.
>Why not use reference-counting as a first resort, only falling back to GC w=
>hen you need to, like Perl and Python do?
As others have mentioned, that would be inefficient. Moreover, having
both reference counting and GC is more complex than necessary. Most
importantly, you would have to prefix all operations that deal with
references in order to add the reference counting; e.g., RDUP ROVER R@
R!; if the programmer forgets this once, the invariant of reference
counting is broken, and such bugs are not easy to find. For Python
and Perl, that's no problem, because there the system keeps track of
references (by tagging).
- anton
--
M. Anton Ertl http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
New standard: http://www.forth200x.org/forth200x.html
EuroForth 2016: http://www.euroforth.org/ef16/
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Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-08-29 18:41 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-08-29 09:39 -0700
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-08-30 10:49 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-08-29 09:46 -0700
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-08-30 11:07 +0200
Re: Implementing lisp in Forth. Chapter 4. Rod Pemberton <NoHaveNotOne@zxdehrnyya.cam> - 2016-08-30 08:00 -0400
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-02 12:34 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-08-31 14:23 -0700
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-01 02:15 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-01 19:49 -0700
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-02 11:49 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-04 11:28 -0700
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-05 03:31 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-04 21:03 -0700
Re: Implementing lisp in Forth. Chapter 4. Spiros Bousbouras <spibou@gmail.com> - 2016-09-05 07:47 +0000
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-05 12:05 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-05 12:04 -0700
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-06 11:48 +0200
Re: Implementing lisp in Forth. Chapter 4. Spiros Bousbouras <spibou@gmail.com> - 2016-09-06 15:32 +0000
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-06 21:27 +0200
Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-06 19:50 +0000
Re: Implementing lisp in Forth. Chapter 4. Stefan Monnier <monnier@iro.umontreal.ca> - 2016-09-08 12:15 -0400
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-08 20:09 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-08 12:34 -0700
Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 10:17 +0000
Re: Implementing lisp in Forth. Chapter 4. Stefan Monnier <monnier@iro.umontreal.ca> - 2016-09-12 11:50 -0400
Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 16:48 +0000
Re: Implementing lisp in Forth. Chapter 4. Stefan Monnier <monnier@iro.umontreal.ca> - 2016-09-12 13:41 -0400
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-06 22:03 -0700
Re: Implementing lisp in Forth. Chapter 4. George Neuner <gneuner2@comcast.net> - 2016-09-08 16:50 -0400
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-08 16:34 -0700
Re: Implementing lisp in Forth. Chapter 4. George Neuner <gneuner2@comcast.net> - 2016-09-09 00:12 -0400
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-08 22:22 -0700
Re: Implementing lisp in Forth. Chapter 4. Lars Brinkhoff <lars.spam@nocrew.org> - 2016-09-27 08:51 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-27 00:47 -0700
Re: Implementing lisp in Forth. Chapter 4. Spiros Bousbouras <spibou@gmail.com> - 2016-09-06 13:18 +0000
Re: Implementing lisp in Forth. Chapter 4. "WJ" <w_a_x_man@yahoo.com> - 2016-09-06 20:52 +0000
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-02 19:15 +0100
Re: Implementing lisp in Forth. Chapter 4. Lars Brinkhoff <lars.spam@nocrew.org> - 2016-09-09 10:05 +0200
Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 10:11 +0000
Re: Implementing lisp in Forth. Chapter 4. Lars Brinkhoff <lars.spam@nocrew.org> - 2016-09-12 13:15 +0200
Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 17:25 +0000
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-09 16:19 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-09 10:55 -0700
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-09 21:39 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-09 13:06 -0700
Re: Implementing lisp in Forth. Chapter 4. franck.bensusan@gmail.com - 2016-09-10 07:23 -0700
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-11 01:28 -0700
Re: Implementing lisp in Forth. Chapter 4. Spiros Bousbouras <spibou@gmail.com> - 2016-09-13 21:37 +0000
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-14 09:55 +0200
Re: Implementing lisp in Forth. Chapter 4. franck.bensusan@gmail.com - 2016-09-14 01:04 -0700
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-13 14:40 -0700
Re: Implementing lisp in Forth. Chapter 4. franck.bensusan@gmail.com - 2016-09-14 03:37 -0700
Re: Implementing lisp in Forth. Chapter 4. lawrencedo99@gmail.com - 2016-09-10 01:17 -0700
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-10 12:01 -0700
Re: Implementing lisp in Forth. Chapter 4. lawrencedo99@gmail.com - 2016-09-10 21:57 -0700
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-10 22:12 -0700
Re: Implementing lisp in Forth. Chapter 4. lawrencedo99@gmail.com - 2016-09-10 23:30 -0700
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-10 23:48 -0700
Re: Implementing lisp in Forth. Chapter 4. Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-09-11 02:59 -0500
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-11 01:16 -0700
Re: Implementing lisp in Forth. Chapter 4. lawrencedo99@gmail.com - 2016-09-11 19:02 -0700
Re: Implementing lisp in Forth. Chapter 4. lawrencedo99@gmail.com - 2016-09-11 19:00 -0700
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-10 12:08 -0700
Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 09:43 +0000
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-12 13:42 +0200
Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-12 17:26 +0000
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-12 20:56 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-12 13:08 -0700
Re: Implementing lisp in Forth. Chapter 4. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-09-14 07:38 +0000
Re: Implementing lisp in Forth. Chapter 4. Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2016-09-30 07:48 +0100
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-30 11:22 +0200
Re: Implementing lisp in Forth. Chapter 4. Paul Rubin <no.email@nospam.invalid> - 2016-09-30 18:36 -0700
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-10-01 11:19 +0200
Re: Implementing lisp in Forth. Chapter 4. luser droog <mijoryx@yahoo.com> - 2016-10-01 19:34 -0700
Implementing lisp in Forth. Garbage collection. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-06 12:30 +0200
Re: Implementing lisp in Forth. Garbage collection. Spiros Bousbouras <spibou@gmail.com> - 2016-09-06 15:34 +0000
Re: Implementing lisp in Forth. Garbage collection. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-06 21:12 +0200
Re: Implementing lisp in Forth. Garbage collection. Paul Rubin <no.email@nospam.invalid> - 2016-09-06 14:52 -0700
Re: Implementing lisp in Forth. Garbage collection. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-09-07 01:50 +0200
Re: Implementing lisp in Forth. Garbage collection. Paul Rubin <no.email@nospam.invalid> - 2016-09-06 17:49 -0700
Re: Implementing lisp in Forth. Chapter 4. luser droog <mijoryx@yahoo.com> - 2016-10-21 17:02 -0700
Re: Implementing lisp in Forth. Chapter 4. albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-10-22 02:43 +0200
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