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Re: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64)

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On 2013-03-09, Roy Smith <roy@panix.com> wrote:
> In article <khg6f3$cfr$1@reader2.panix.com>,
>  Grant Edwards <invalid@invalid.invalid> wrote:
>
>> What I should have said was that there's no way to return to the OS
>> memory obtained via calls to malloc() et al.
>
> That's true (for certain values of "et al").
>
>> and those are the calls that "good" C programmers (like the
>> maintainers of CPython) use.
>
> Well, there is mmap, which is exposed via the Python mmap module.  
> Python doesn't have anything like C++'s "placement new", so there's
> no way to use that memory to hold generic Python objects, but you can
> certainly use mmap to allocate a large chunk of memory, use it, and
> then give it back to the OS.

[example]

I was surprised to find that the object returned by mmap.mmap()
supported file semantics (seek, tell, read, etc.) in addition to byte
buffer semantics.  Usually, the reason one maps a file is that one
doesn't want to use file semantics (which are already supported by the
file object) but wants instead to use buffer semantics.

Using memmap to obtain a "returnable" chunk of memory seems a bit
obtuse, since it requires creating an underlying file of appropriate
size that ends up being superfluous.

-- 
Grant Edwards               grant.b.edwards        Yow! I wonder if I ought
                                  at               to tell them about my
                              gmail.com            PREVIOUS LIFE as a COMPLETE
                                                   STRANGER?

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sync databse table based on current directory data without losign previous values Νίκος Γκρ33κ <nikos.gr33k@gmail.com> - 2013-03-05 23:45 -0800
  Re: sync databse table based on current directory data without losign previous values Lele Gaifax <lele@metapensiero.it> - 2013-03-06 09:19 +0100
    Re: sync databse table based on current directory data without losign previous values Νίκος Γκρ33κ <nikos.gr33k@gmail.com> - 2013-03-06 00:57 -0800
      Re: sync databse table based on current directory data without losign previous values Lele Gaifax <lele@metapensiero.it> - 2013-03-06 10:24 +0100
        Re: sync databse table based on current directory data without losign previous values Νίκος Γκρ33κ <nikos.gr33k@gmail.com> - 2013-03-06 01:41 -0800
          Re: sync databse table based on current directory data without losign previous values Νίκος Γκρ33κ <nikos.gr33k@gmail.com> - 2013-03-06 01:43 -0800
            Re: sync databse table based on current directory data without losign previous values Bryan Devaney <bryan.devaney@gmail.com> - 2013-03-06 02:15 -0800
            Re: sync databse table based on current directory data without losign previous values Bryan Devaney <bryan.devaney@gmail.com> - 2013-03-06 02:15 -0800
          Re: sync databse table based on current directory data without losign previous values Νίκος Γκρ33κ <nikos.gr33k@gmail.com> - 2013-03-06 01:43 -0800
          Re: sync databse table based on current directory data without losign previous values Lele Gaifax <lele@metapensiero.it> - 2013-03-06 11:27 +0100
          Re: sync databse table based on current directory data without losign previous values Dave Angel <davea@davea.name> - 2013-03-06 08:31 -0500
          Re: sync databse table based on current directory data without losign previous values Lele Gaifax <lele@metapensiero.it> - 2013-03-06 15:16 +0100
        Re: sync databse table based on current directory data without losign previous values Νίκος Γκρ33κ <nikos.gr33k@gmail.com> - 2013-03-06 01:41 -0800
    Re: sync databse table based on current directory data without losign previous values Νίκος Γκρ33κ <nikos.gr33k@gmail.com> - 2013-03-06 00:57 -0800
  Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Wong Wah Meng-R32813 <r32813@freescale.com> - 2013-03-06 10:11 +0000
    Re: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Bryan Devaney <bryan.devaney@gmail.com> - 2013-03-06 02:25 -0800
      RE: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Wong Wah Meng-R32813 <r32813@freescale.com> - 2013-03-06 12:31 +0000
      Re: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Dave Angel <davea@davea.name> - 2013-03-06 08:18 -0500
      Re: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Dave Angel <davea@davea.name> - 2013-03-06 08:25 -0500
    Re: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Bryan Devaney <bryan.devaney@gmail.com> - 2013-03-06 02:25 -0800
    Re: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-03-06 23:34 +0000
      RE: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Wong Wah Meng-R32813 <r32813@freescale.com> - 2013-03-07 06:33 +0000
      Re: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Chris Angelico <rosuav@gmail.com> - 2013-03-07 18:19 +1100
      RE: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Wong Wah Meng-R32813 <r32813@freescale.com> - 2013-03-08 09:08 +0000
      Re: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-03-08 19:40 -0500
      RE: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Wong Wah Meng-R32813 <r32813@freescale.com> - 2013-03-09 08:07 +0000
        Re: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Grant Edwards <invalid@invalid.invalid> - 2013-03-09 19:18 +0000
          Re: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Roy Smith <roy@panix.com> - 2013-03-09 15:04 -0500
            Re: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Grant Edwards <invalid@invalid.invalid> - 2013-03-09 20:35 +0000
              Re: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Roy Smith <roy@panix.com> - 2013-03-09 16:44 -0500
                Re: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Grant Edwards <invalid@invalid.invalid> - 2013-03-11 14:27 +0000
      Re: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Dave Angel <davea@davea.name> - 2013-03-09 06:02 -0500
      Re: Set x to to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Isaac To <isaac.to@gmail.com> - 2013-03-09 23:02 +0800
  Re: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Terry Reedy <tjreedy@udel.edu> - 2013-03-06 05:59 -0500
  Re: sync databse table based on current directory data without losign previous values Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-03-06 11:52 +0000
  RE: Set x to  to None and del x doesn't release memory in python 2.7.1 (HPUX 11.23, ia64) Wong Wah Meng-R32813 <r32813@freescale.com> - 2013-03-06 12:36 +0000
  Re: sync databse table based on current directory data without losign previous values Chris Angelico <rosuav@gmail.com> - 2013-03-07 00:40 +1100
  Re: sync databse table based on current directory data without losign previous values "Michael Ross" <gmx@ross.cx> - 2013-03-06 15:04 +0100
    Re: sync databse table based on current directory data without losign previous values nagia.retsina@gmail.com - 2013-03-06 08:09 -0800
    Re: sync databse table based on current directory data without losign previous values nagia.retsina@gmail.com - 2013-03-06 08:09 -0800

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