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Re: php daemon [message #179594 is a reply to message #179593]

Sun, 11 November 2012 21:22

Christoph Becker
Messages: 91
Registered: June 2012

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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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[Message index]

		php daemon By: SL on Sun, 11 November 2012 17:18
		Re: php daemon By: Jerry Stuckle on Sun, 11 November 2012 19:04
		Re: php daemon By: Christoph Becker on Sun, 11 November 2012 20:05
		Re: php daemon By: Jerry Stuckle on Sun, 11 November 2012 20:35
		Re: php daemon By: Christoph Becker on Sun, 11 November 2012 21:22
		Re: php daemon By: Jerry Stuckle on Sun, 11 November 2012 21:36
		Re: php daemon By: Christoph Becker on Sun, 11 November 2012 22:17
		Re: php daemon By: Jerry Stuckle on Sun, 11 November 2012 23:11
		Re: php daemon By: Christoph Becker on Mon, 12 November 2012 13:35
		Re: php daemon By: Jerry Stuckle on Mon, 12 November 2012 13:38
		Re: php daemon By: Jerry Stuckle on Tue, 13 November 2012 12:44
		Re: php daemon By: Christoph Becker on Wed, 14 November 2012 20:19
		Re: php daemon By: Jerry Stuckle on Wed, 14 November 2012 21:33
		Re: php daemon By: Christoph Becker on Wed, 14 November 2012 22:13
		Re: php daemon By: Jerry Stuckle on Thu, 15 November 2012 12:41
		Re: php daemon By: Christoph Becker on Thu, 15 November 2012 15:55
		Re: php daemon By: SL on Mon, 12 November 2012 15:45
		Re: php daemon By: The Natural Philosoph on Mon, 12 November 2012 16:08
		Re: php daemon By: Goran on Tue, 13 November 2012 07:57
		Re: php daemon By: Jerry Stuckle on Tue, 13 November 2012 12:47
		Re: php daemon By: Goran on Tue, 13 November 2012 13:54
		Re: php daemon By: The Natural Philosoph on Tue, 13 November 2012 14:13
		Re: php daemon By: Jerry Stuckle on Tue, 13 November 2012 17:23
		Re: php daemon By: Goran on Wed, 14 November 2012 07:43
		Re: php daemon By: Jerry Stuckle on Wed, 14 November 2012 10:51
		Re: php daemon By: Goran on Thu, 15 November 2012 13:08
		Re: php daemon By: Jerry Stuckle on Thu, 15 November 2012 13:46
		Re: php daemon By: Goran on Thu, 15 November 2012 15:09
		Re: php daemon By: Jerry Stuckle on Thu, 15 November 2012 16:25
		Re: php daemon By: Tim Streater on Thu, 15 November 2012 16:20

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