Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:55148
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.214.42 as permitted sender)
MIME-Version: 1.0
Sender: ekneuss@gmail.com
In-Reply-To: <CAL0xaBEG1LBfLSNS7fFhK+Wb700oock0DtuQfe3A5cVhBuoiYg@mail.gmail.com>
References: <CACs9DU4jhCBHEYXd-N1rvYE5jbCDztvXEi=gsZh4ozLoqQrRXw@mail.gmail.com>
	<CACs9DU5EsXi1jUDnswOCFiEOMgitOPDQE-X_Pp_G_9L4=dsdkQ@mail.gmail.com>
	<CAEZPtU79jxjT52=1HYRfaDE0z6cb5pDGD9h4czspiHaOC_-Kyg@mail.gmail.com>
	<CACs9DU6_oDZAKEDvOxybSvXR5moDCP2ZM=WhLEe+Ui=EkpuToQ@mail.gmail.com>
	<CACQesk5_bRDXCpuhB-bDb1LF4ks7s1pzSPo90EuSb-NtbPGxRQ@mail.gmail.com>
	<CAM4sM9Hb3Qyig8xssrJd3YWq9L60xQkXHG9sY9=XOD37wFXLog@mail.gmail.com>
	<4E39E89F.8060605@sugarcrm.com>
	<4E3A3643.2070305@toolpark.com>
	<4E3A4793.2070209@sugarcrm.com>
	<4E3A91E8.1020107@toolpark.com>
	<4E3ACA42.8000001@sugarcrm.com>
	<CAH-PCH4+KTZYd6cNC-MaC8wu2sxK1BXC967c1yiA-ohXFPgOiQ@mail.gmail.com>
	<CAGsnKxb_F-xG-grZUaCv8D=Yrs0=0YE9a8H+Z7_TNXOnjq3+=A@mail.gmail.com>
	<4E3BF930.9030701@toolpark.com>
	<CACs9DU6S3NcppNYoTgtMwuyCO7ygGu6jOm665b9UMQtnqB2zQw@mail.gmail.com>
	<4E3C5EDE.3030401@toolpark.com>
	<CAH-PCH63q-BmVHXWmXhg-SDx3oxhAw=psVuA3TgppeJds9yNXQ@mail.gmail.com>
	<CACs9DU4fiORJoDaYAXm4=2m8F-1BBx2OORgozvvJv723Haxsrw@mail.gmail.com>
	<4E3D073A.9050709@toolpark.com>
	<CAL0xaBEG1LBfLSNS7fFhK+Wb700oock0DtuQfe3A5cVhBuoiYg@mail.gmail.com>
Date: Sat, 3 Sep 2011 13:54:04 +0200
Message-ID: <CACQesk6C0J=Eo5ontTyDrhqen9WYu1e5Lhj=6HNMvo3V+kXAzg@mail.gmail.com>
To: Arvids Godjuks <arvids.godjuks@gmail.com>
Cc: internals@lists.php.net
Content-Type: multipart/alternative; boundary=0015175cd5f2761b5404ac082275
Subject: Re: [PHP-DEV] [VOTE] Weak References
From: colder@php.net (Etienne Kneuss)

--0015175cd5f2761b5404ac082275
Content-Type: text/plain; charset=UTF-8

Hi,

On Tue, Aug 9, 2011 at 14:22, Arvids Godjuks <arvids.godjuks@gmail.com>wrote:

> I have mixed feelings about this proposal - from one point it's quite
> neat - ability to mark circular references for the memory manager so
> it can free them sounds very delicious, especially for some cases. I
> had run into my own bunch of problems with memory in PHP in the past
> and right now I'm running a daemon written in PHP in production on
> 5.3.6. Careful construction and knowledge that circular references
> actually do harm I did add safeguards that actually clean up the
> objects in recursive manner (and objects have internal flags that
> cleanup has been initiated - that way I make sure I cleanup the same
> object only once). That sort of planing at the design stage makes it
> far more friendly with memory, so it doesn't mean that PHP should have
> soft references.
>
> My opinion is that if this can be done without using significant
> resources and will not have major issues while implementing - it can
> be added, otherwise just skip it - better off fixing bugs and
> optimizing :)
>

Weak references have been implemented in a PECL extension since weeks now:
http://php.net/weakref and/or http://pecl.php.net/weakref

It feels like you're beating up a dead horse here.

A discussion for bundling it might occur in the future, but given the
feedbacks PECL might very well be the right place for it.

Best,


>
> 2011/8/6 Lars Schultz <lars.schultz@toolpark.com>:
> > Am 06.08.2011 02:14, schrieb Hannes Landeholm:
> >>
> >> Yeah I think there's a lot of misunderstandings going on with weak/soft
> >> references and how the garbage collector works. Weak/soft references is
> >> not
> >> some kind of solution to the cyclic reference problem. The GC takes care
> >> of
> >> that already. You can use whatever OOP patterns with whatever reference
> >> graphs you like Lars, the GC will free the entire structure as soon as
> the
> >> cyclic collector runs after you are not referencing it anymore. You
> might
> >> have become a bit confused with my last post where I explained how one
> >> could
> >> theoretically hack together a soft reference implementation by using
> weak
> >> references and some properties of cyclic collection. Also property
> access
> >> performance is off-topic.
> >
> > I did not misunderstand how weak/soft-references or php's new GC works.
> >
> > Having a GC collect circular references is neat, but if I remember
> > correctly, collecting them (which is why there are other, faster methods
> but
> > which require more memory) is neither simple nor fast (whatever that
> means)
> > so...if I can assist the GC by clearly stating that my child-objects may
> be
> > collected as soon as they and their parent are not referenced from
> userland
> > anymore thus not requiring the GC and thus freeing memory as soon as
> > possible,...seems like an optimization worth thinking of. Especially if I
> > tend to have vast structures with hundreds of objects.
> >
> > In 5.2 (we can't move our project to 5.3 yet because of a BC issue) i had
> to
> > manually clear those cycles before dropping the last userland reference
> to
> > the tree of objects because otherwise I'd run into memory problems when
> > processing alot of those trees.
> >
> >
> > --
> > PHP Internals - PHP Runtime Development Mailing List
> > To unsubscribe, visit: http://www.php.net/unsub.php
> >
> >
>
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>


-- 
Etienne Kneuss
http://www.colder.ch

--0015175cd5f2761b5404ac082275--