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From: Wong Wah Meng-R32813 <r32813@freescale.com>
To: Terry Reedy <tjreedy@udel.edu>, "python-list@python.org" <python-list@python.org>
Subject: RE: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64)
Thread-Topic: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64)
Thread-Index: AQHOGlrjUSW9o23MW0CM+iogfRkkn5iYmJsA
Date: Wed, 6 Mar 2013 12:36:04 +0000
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Thanks for youre reply. I built python 2.7.1 binary myself on the HP box an=
d I wasn't aware there is any configuration or setup that I need to modify =
in order to activate or engage the garbage collection (or even setting the =
memory size used). Probably you are right it leaves it to the OS itself (in=
 this case HP-UX) to clean it up as after python removes the reference to t=
he address of the variables the OS still thinks the python process should s=
till owns it until the process exits.=20

Regards,
Wah Meng=20

-----Original Message-----
From: Python-list [mailto:python-list-bounces+wahmeng=3Dfreescale.com@pytho=
n.org] On Behalf Of Terry Reedy
Sent: Wednesday, March 06, 2013 7:00 PM
To: python-list@python.org
Subject: Re: Set x to to None and del x doesn't release memory in python 2.=
7.1 (HPUX 11.23, ia64)

On 3/6/2013 5:11 AM, Wong Wah Meng-R32813 wrote:
> Hello there,
>
> I am using python 2.7.1 built on HP-11.23 a Itanium 64 bit box.
>
> I discovered following behavior whereby the python process doesn't=20
> seem to release memory utilized even after a variable is set to None,=20
> and "deleted". I use glance tool to monitor the memory utilized by=20
> this process. Obviously after the for loop is executed, the memory=20
> used by this process has hiked to a few MB. However, after "del" is=20
> executed to both I and str variables, the memory of that process still=20
> stays at where it was.

Whether memory freed by deleting an object is returned to and taken by the =
OS depends on the OS and other factors like like the size and layout of the=
 freed memory, probably the history of memory use, and for CPython, the C c=
ompiler's malloc/free implementation. At various times, the Python memory h=
andlers have been rewritten to encourage/facilitate memory return, but Pyth=
on cannot control the process.

> for i in range(100000L):
>      str=3Dstr+"%s"%(i,)
> i=3DNone; str=3DNone   # not necessary
 > del i; del str

Reusing built-in names for unrelated purposes is generally a bad idea, alth=
ough the final deletion does restore access to the builtin.

--
Terry Jan Reedy

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