ruby-gnome2-devel-en

[ruby-gnome2-devel-en] ref and unref

[<jc...@gm...>]

Hello everyone,

I'm trying to use the ruby-gnome2 gobject-introspection package to
help make a Ruby binding for my GObject-based image processing
library.

I have a general question about memory management: how is reference
counting handled? For example, if I create a new object like this:

   a = Vips::Image.new

and then get rid of the reference:

   a = nil
   GC.start

I would expect the object to be unreffed. Is there some extra magic I need?

Tiny test program here:

   https://github.com/jcupitt/ruby-vips8/blob/master/try/try2.rb

John

Re: [ruby-gnome2-devel-en] ref and unref

[Kouhei S. <ko...@co...>]

Hi,

In <CAGNS0RsW3zKxgo=aX-...@ma...>
  "[ruby-gnome2-devel-en] ref and unref" on Wed, 7 Jan 2015 16:41:51 +0000,
  jc...@gm... wrote:

> I'm trying to use the ruby-gnome2 gobject-introspection package to
> help make a Ruby binding for my GObject-based image processing
> library.
> 
> I have a general question about memory management: how is reference
> counting handled? For example, if I create a new object like this:
> 
>    a = Vips::Image.new
> 
> and then get rid of the reference:
> 
>    a = nil
>    GC.start
> 
> I would expect the object to be unreffed. Is there some extra magic I need?

No. You don't need to anything.
gobject-introspection gem (and glib2 gem) does everything.


Try the following code:

---
class X
end

a = X.new
a = nil
GC.start
p(ObjectSpace.each_object(X) {})
---

It'll print "1".

And also try the following code:

---
class X
end

1.times do
  X.new
end
GC.start
p(ObjectSpace.each_object(X) {})
---

It'll print "0".


I hope that they give you some hints.


Thanks,
--
kou

Re: [ruby-gnome2-devel-en] ref and unref

[<jc...@gm...>]

Hi Kou, thank you very much for helping me.

On 8 January 2015 at 14:50, Kouhei Sutou <ko...@co...> wrote:
>> I have a general question about memory management: how is reference
>> counting handled? For example, if I create a new object like this:
>>
>>    a = Vips::Image.new
>>
>> and then get rid of the reference:
>>
>>    a = nil
>>    GC.start
>>
>> I would expect the object to be unreffed. Is there some extra magic I need?
>
> No. You don't need to anything.
> gobject-introspection gem (and glib2 gem) does everything.

It doesn't seem to work for me. If I run:

10000.times do
    Vips::Image.new
end
GC.start

I still have 10,000 GObjects, each with one ref.

My code is here:

https://github.com/jcupitt/ruby-vips8/blob/master/try/try2.rb#L98

Perhaps I am missing something in my loader class?

Vips::image.new calls vips_image_new(), which just does g_object_new():

https://github.com/jcupitt/libvips/blob/master/libvips/iofuncs/image.c#L1681

John

Re: [ruby-gnome2-devel-en] ref and unref

[Kouhei S. <ko...@co...>]

Hi,

In <CAG...@ma...>
  "Re: [ruby-gnome2-devel-en] ref and unref" on Thu, 8 Jan 2015 16:39:45 +0000,
  jc...@gm... wrote:

> It doesn't seem to work for me. If I run:
> 
> 10000.times do
>     Vips::Image.new
> end
> GC.start
> 
> I still have 10,000 GObjects, each with one ref.

Really?

> My code is here:
> 
> https://github.com/jcupitt/ruby-vips8/blob/master/try/try2.rb#L98

I run the code with the following diff:

--
diff --git a/try/try2.rb b/try/try2.rb
index 53c4272..0b214fa 100755
--- a/try/try2.rb
+++ b/try/try2.rb
@@ -97,6 +97,8 @@ end
 10000.times do
     Vips::Image.new
 end
+p(ObjectSpace.each_object(Vips::Image) {})
 GC.start
+p(ObjectSpace.each_object(Vips::Image) {})
 
 
--

I got the following:

--
Vips::const_missing: Image
Vips::init: []
Vips::Loader.initialize: Vips, []
Vips::Loader.pre_load: #<GObjectIntrospection::Repository:0x0000000286eaa0>, Vips
Vips::Loader.call_init_function: #<GObjectIntrospection::Repository:0x0000000286eaa0>, Vips
Vips::Loader.post_load:
41
0
--

Did you use the latest gobject-introspection gem? I used
gobject-introspection 2.2.4 gem:

--
% gem list gobject-introspection
*** LOCAL GEMS ***

gobject-introspection (2.2.4)
--

Thanks,
--
kou

Re: [ruby-gnome2-devel-en] ref and unref

[<jc...@gm...>]

Ooop, excuse me, I think I found my problem.

gobject-introspection seems to be reffing the object it gets back from
vips_image_new(), even though constructors should not do this (I
think). How can I stop gobject-introspection from making this extra
reference?

If I run this code:

x = Vips::Image.new
x.print_dump

at the end of the C vips_image_new() function, the object has a
reference count of 1. But when x.print_dump runs, I see a count of 2.
When I then run:

x = nil
GC.start

the count drops to 1, but never to zero, so the object is not freed.

I tried adding a (transfer full) annotation to vips_image_new(), but
it made no difference, gobject-introspection still made an extra
g_object_ref() during new.

John

Re: [ruby-gnome2-devel-en] ref and unref

[<jc...@gm...>]

On 31 January 2015 at 12:47, Kouhei Sutou <ko...@co...> wrote:
> I've fixed it at master. Could you try master again?

It works!! I now see:

--------------------
$ ./example1.rb

starting up:
Vips::method_missing: leak_set, [true],
Vips::init: []
Vips::Loader.initialize: Vips, []
Vips::Loader.pre_load:
#<GObjectIntrospection::Repository:0x00000001d3fe18>, Vips
Vips::Loader.call_init_function:
#<GObjectIntrospection::Repository:0x00000001d3fe18>, Vips
Vips::Loader.post_load:

creating object:
1x1 uchar, 1 band, multiband, partial VipsImage (0x20a7010)
1 objects alive:
0) VipsImage (0x20a7010), count=1
VipsImage (image), image class 1x1 uchar, 1 band, multiband

freeing object:

shutting down:
memory: high-water mark 0 bytes
-------------------

Wonderful, thank you very much kou.

John

Re: [ruby-gnome2-devel-en] ref and unref

[Kouhei S. <ko...@co...>]

Hi,

In <CAG...@ma...>
  "Re: [ruby-gnome2-devel-en] ref and unref" on Sat, 31 Jan 2015 13:40:05 +0000,
  jc...@gm... wrote:

>> I've fixed it at master. Could you try master again?
> 
> It works!! I now see:

Thanks for confirming it!

--
kou

Re: [ruby-gnome2-devel-en] ref and unref

[Kouhei S. <ko...@co...>]

Hi,

Thanks for the information!
I've fixed it at master. Could you try master again?

Thanks,
--
kou

In <CAG...@ma...>
  "Re: [ruby-gnome2-devel-en] ref and unref" on Fri, 30 Jan 2015 14:07:06 +0000,
  jc...@gm... wrote:

> Ooop, excuse me, I think I found my problem.
> 
> gobject-introspection seems to be reffing the object it gets back from
> vips_image_new(), even though constructors should not do this (I
> think). How can I stop gobject-introspection from making this extra
> reference?
> 
> If I run this code:
> 
> x = Vips::Image.new
> x.print_dump
> 
> at the end of the C vips_image_new() function, the object has a
> reference count of 1. But when x.print_dump runs, I see a count of 2.
> When I then run:
> 
> x = nil
> GC.start
> 
> the count drops to 1, but never to zero, so the object is not freed.
> 
> I tried adding a (transfer full) annotation to vips_image_new(), but
> it made no difference, gobject-introspection still made an extra
> g_object_ref() during new.
> 
> John
> 
> ------------------------------------------------------------------------------
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Re: [ruby-gnome2-devel-en] ref and unref

[<jc...@gm...>]

Hello again, sorry for the long delay, I was called off onto another project.

On 11 January 2015 at 08:44, Kouhei Sutou <ko...@co...> wrote:
>> It doesn't seem to work for me. If I run:
>>
>> 10000.times do
>>     Vips::Image.new
>> end
>> GC.start
>>
>> I still have 10,000 GObjects, each with one ref.
>
> I got the following:
>
> --
> Vips::const_missing: Image
> Vips::init: []
> Vips::Loader.initialize: Vips, []
> Vips::Loader.pre_load: #<GObjectIntrospection::Repository:0x0000000286eaa0>, Vips
> Vips::Loader.call_init_function: #<GObjectIntrospection::Repository:0x0000000286eaa0>, Vips
> Vips::Loader.post_load:
> 41
> 0

Thank you for trying this.

That's counting instances of the Ruby classes, which I agree are being
freed. But the underlying GObjects are not being unreffed.

If you put a breakpoint on vips_object_finalize(), for example, it is
never called.

How can I get gobject-introspection to call g_object_unref() whan an
object is removed by GC?

> Did you use the latest gobject-introspection gem? I used
> gobject-introspection 2.2.4 gem:

Yes, I'm using 2.2.4.

John