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Groups > comp.lang.php > #7525

Re: php daemon

From Christoph Becker <cmbecker69@gmx.de>
Newsgroups comp.lang.php
Subject Re: php daemon
Date 2012-11-11 22:22 +0100
Organization Aioe.org NNTP Server
Message-ID <k7p4t3$ap2$1@speranza.aioe.org> (permalink)
References <k7omm2$lbq$1@news.albasani.net> <k7osrj$ipv$2@dont-email.me> <k7p0ch$urc$1@speranza.aioe.org> <k7p27m$kte$1@dont-email.me>

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Jerry Stuckle wrote:
> On 11/11/2012 3:05 PM, Christoph Becker wrote:
>> Jerry Stuckle wrote:
>>> All you can do is unset() variables.  However, this does not release
>>> memory immediately.  It would wait for the garbage collector to run.
>>
>> I'm very much surprised.  I /assumed/ that PHP uses reference counting,
>> which would typically release the allocated memory as soon as the
>> reference count of a value is 0.
>>
> 
> It does.  But memory is not released until the garbage collector is run.
>  See the PHP documentation.

Thanks for the pointer to the PHP documentation.  According to
<http://php.net/manual/en/features.gc.refcounting-basics.php>:

| A PHP variable is stored in a container called a "zval". A zval
| container contains, besides the variable's type and value, two
| additional bits of information.
| [...]
| Variable containers get destroyed when the "refcount" reaches zero.
| [...]
| Again, when the "refcount" reaches zero, the variable container is
| removed from memory.

As this simple reference counting garbage collection isn't able to free
circular structures, a garbage collector [1] to do so was introduced in
PHP 5.3.  Unfortunately the documentation isn't particularly clear here:

| If the refcount is decreased and hits zero, the zval can be freed.

But from the subsequent documentation I conclude, that the zval is
actually freed, when the refcount is decreased to zero.

[1] <http://www.php.net/manual/en/features.gc.collecting-cycles.php

-- 
Christoph M. Becker

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Thread

php daemon "sl@exabyte" <sb5309@hotmail.com> - 2012-11-12 01:18 +0800
  Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-11 14:04 -0500
    Re: php daemon Christoph Becker <cmbecker69@gmx.de> - 2012-11-11 21:05 +0100
      Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-11 15:35 -0500
        Re: php daemon Christoph Becker <cmbecker69@gmx.de> - 2012-11-11 22:22 +0100
          Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-11 16:36 -0500
            Re: php daemon Christoph Becker <cmbecker69@gmx.de> - 2012-11-11 23:17 +0100
              Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-11 18:11 -0500
                Re: php daemon Christoph Becker <cmbecker69@gmx.de> - 2012-11-12 14:35 +0100
                Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-12 08:38 -0500
                Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-13 07:44 -0500
                Re: php daemon Christoph Becker <cmbecker69@gmx.de> - 2012-11-14 21:19 +0100
                Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-14 16:33 -0500
                Re: php daemon Christoph Becker <cmbecker69@gmx.de> - 2012-11-14 23:13 +0100
                Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-15 07:41 -0500
                Re: php daemon Christoph Becker <cmbecker69@gmx.de> - 2012-11-15 16:55 +0100
    Re: php daemon "sl@exabyte" <sb5309@hotmail.com> - 2012-11-12 23:45 +0800
      Re: php daemon The Natural Philosopher <tnp@invalid.invalid> - 2012-11-12 16:08 +0000
  Re: php daemon Goran <goran@nospam.com> - 2012-11-13 08:57 +0100
    Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-13 07:47 -0500
      Re: php daemon Goran <goran@nospam.com> - 2012-11-13 14:54 +0100
        Re: php daemon The Natural Philosopher <tnp@invalid.invalid> - 2012-11-13 14:13 +0000
        Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-13 12:23 -0500
          Re: php daemon Goran <goran@nospam.com> - 2012-11-14 08:43 +0100
            Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-14 05:51 -0500
              Re: php daemon Goran <goran@nospam.com> - 2012-11-15 14:08 +0100
                Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-15 08:46 -0500
                Re: php daemon Goran <goran@nospam.com> - 2012-11-15 16:09 +0100
                Re: php daemon Jerry Stuckle <jstucklex@attglobal.net> - 2012-11-15 11:25 -0500
                Re: php daemon Tim Streater <timstreater@greenbee.net> - 2012-11-15 16:20 +0000

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