Garbage collector

_Eustaquio_Rangel_de · 8 January 2005 22:06

Hi!

Hey, how often the garbage collector runs?
When all the memory becomes full?
Or there is a pre-defined interval?

And, do you have some links about the the Ruby mark-and-sweep type of
garbage?

Thanks!

- ----------------------------
Eustáquio "TaQ" Rangel
eustaquiorangel@yahoo.com
http://beam.to/taq
Usuário GNU/Linux no. 224050

Bill_Atkins · 8 January 2005 22:18

It runs when Ruby runs out of memory or when it's manually invoked (by
ObjectSpace.garbage_collect or GC.start).

Bill

···

On Sun, 9 Jan 2005 07:06:36 +0900, "Eustáquio Rangel de Oliveira Jr." <eustaquiorangel@yahoo.com> wrote:

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Hash: SHA1

Hi!

Hey, how often the garbage collector runs?
When all the memory becomes full?
Or there is a pre-defined interval?

And, do you have some links about the the Ruby mark-and-sweep type of
garbage?

Thanks!

- ----------------------------
Eustáquio "TaQ" Rangel
eustaquiorangel@yahoo.com
The easiest way to create, record and stream live video - Beings
Usuário GNU/Linux no. 224050
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--
$stdout.sync = true
"Just another Ruby hacker.".each_byte do |b|
('a'..'z').step do|c|print c+"\b";sleep 0.007 end;print b.chr
end; print "\n"

Charles_Mills1 · 8 January 2005 22:26

Eustáquio Rangel de Oliveira Jr. wrote:

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Hash: SHA1

Hi!

Hey, how often the garbage collector runs?
When all the memory becomes full?
Or there is a pre-defined interval?

It basically runs when a certain amount of memory is used - see
malloc_increase and malloc_limit in gc.c. Also, if malloc() fails or
attempts to open a file fail do to memory limitations the gc will be
run.

And, do you have some links about the the Ruby mark-and-sweep type of
garbage?

-Charlie

gabriele_renzi · 9 January 2005 02:16

Eustáquio Rangel de Oliveira Jr. ha scritto:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi!

Hey, how often the garbage collector runs?
When all the memory becomes full?
Or there is a pre-defined interval?

And, do you have some links about the the Ruby mark-and-sweep type of
garbage?

Thanks!

btw, I thought 1.9 could see the light of a different GC.. Is someone working on that or is it something still very far in the future?

Martin_Pirker · 9 January 2005 18:06

While I lack the skill to go source diving, I too am interested in more
info about the gc.
We use conservative gc [talk:102873], ok

So, can one help gc?
e.g. if an Array or Hash is no longer needed, does an Array.clear or
Hash.clear actually zero all internal pointers to help/speed up gc?

How much extra memory does every Ruby object allocation take?
Any alignment losses?

Is there e.g. a preallocate for a String - if I know it'll grow to ~10kb
by using << and I don't want to produce so much temp garbage?

Martin

···

"Eustáquio Rangel de Oliveira Jr." <eustaquiorangel@yahoo.com> wrote:

And, do you have some links about the the Ruby mark-and-sweep type of
garbage?

George5 · 9 January 2005 18:40

Martin Pirker wrote:

And, do you have some links about the the Ruby mark-and-sweep type of
garbage?

While I lack the skill to go source diving, I too am interested in more
info about the gc.
We use conservative gc [talk:102873], ok

So, can one help gc?
e.g. if an Array or Hash is no longer needed, does an Array.clear or
Hash.clear actually zero all internal pointers to help/speed up gc?

Yes, that should help, as the mark function would no more mark all the value. But I doubt that would be much of a performance win, because if the array-object goes out of scope (it's no more reachable), it's mark function would no longer be called. So, you would not want to call #clear. But that's just my understanding...

Regards,

Michael

···

"Eustáquio Rangel de Oliveira Jr." <eustaquiorangel@yahoo.com> wrote:

Lothar_Scholz2 · 9 January 2005 20:23

Hello Michael,

Martin Pirker wrote:

And, do you have some links about the the Ruby mark-and-sweep type of
garbage?

While I lack the skill to go source diving, I too am interested in more
info about the gc.
We use conservative gc [talk:102873], ok

So, can one help gc?
e.g. if an Array or Hash is no longer needed, does an Array.clear or
Hash.clear actually zero all internal pointers to help/speed up gc?

Yes, that should help, as the mark function would no more mark all the
value. But I doubt that would be much of a performance win, because if
the array-object goes out of scope (it's no more reachable), it's mark
function would no longer be called. So, you would not want to call
#clear. But that's just my understanding...

This would only help if there is something on the stack that looks
like an address to this array object. The chance for this is very low
and so the performance win. With the Boehm-Weisser GC i a measurable
memory reduction (~20%) by doing this for eiffel. But Boehm-Weisser
scans everything conservative and not only the heap like ruby.

···

"Eustáquio Rangel de Oliveira Jr." <eustaquiorangel@yahoo.com> wrote:

--
Best regards, emailto: scholz at scriptolutions dot com
Lothar Scholz http://www.ruby-ide.com
CTO Scriptolutions Ruby, PHP, Python IDE 's

George5 · 9 January 2005 20:35

Lothar Scholz wrote:

Hello Michael,

> Martin Pirker wrote:

And, do you have some links about the the Ruby mark-and-sweep type of
garbage?

While I lack the skill to go source diving, I too am interested in more
info about the gc.
We use conservative gc [talk:102873], ok

So, can one help gc?
e.g. if an Array or Hash is no longer needed, does an Array.clear or
Hash.clear actually zero all internal pointers to help/speed up gc?

> Yes, that should help, as the mark function would no more mark all the
> value. But I doubt that would be much of a performance win, because if
> the array-object goes out of scope (it's no more reachable), it's mark
> function would no longer be called. So, you would not want to call
> #clear. But that's just my understanding...

This would only help if there is something on the stack that looks
like an address to this array object. The chance for this is very low
and so the performance win. With the Boehm-Weisser GC i a measurable
memory reduction (~20%) by doing this for eiffel. But Boehm-Weisser
scans everything conservative and not only the heap like ruby.

Hm, my understanding of Ruby's GC is that it scans the stack conservative (meaning that all values on the stack that look like references to memory are handled as references), but not the heap (how could you conservativly scan the heap?). But probably I misunderstood you.

And my final conclusion was that it does not help much, if any, despite my initial "Yes"

Regards,

Michael

···

"Eustáquio Rangel de Oliveira Jr." <eustaquiorangel@yahoo.com> wrote:

Lothar_Scholz2 · 9 January 2005 21:18

Hello Michael,

memory reduction (~20%) by doing this for eiffel. But Boehm-Weisser
scans everything conservative and not only the heap like ruby.

Hm, my understanding of Ruby's GC is that it scans the stack
conservative (meaning that all values on the stack that look like
references to memory are handled as references), but not the heap (how
could you conservativly scan the heap?). But probably I misunderstood you.

Yes. It was a typo i meant "not only the stack like ruby".
Sorry for the confusion.

···

--
Best regards, emailto: scholz at scriptolutions dot com
Lothar Scholz http://www.ruby-ide.com
CTO Scriptolutions Ruby, PHP, Python IDE 's

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