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Python 32-bit on Windows 64-bit

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Craig Yoshida

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Feb 11, 2011, 1:41:01 PM2/11/11
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what kind of memory limitations to processes running on 32-bit python (with 32-bit C extensions like scipy) have on 64-bit Windows? I'm having occasional MemoryErrors when running a python program on 64-bit Windows 7 that runs fine on my OS X machine. Both machines are using a 64-bit OS and have 4GB of RAM.

Thanks,
-Craig

Michel Claveau - MVP

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Feb 11, 2011, 2:07:07 PM2/11/11
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Hi!

Python 32 bits (& Pywin32) limits are:
2 GB on win.7_32 bits
4 GB on win.7_64 bits

That's what I found in my tests.

@-salutations
--
Michel Claveau


Martin v. Loewis

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Feb 11, 2011, 3:54:25 PM2/11/11
to Craig Yoshida, Python list

In addition to the limitations Michel reports: on a 32-bit system,
objects are typically limited to using at most 2GiB, per object
(of course, you could have at most two objects that come close to
this size, since the whole address space would not be larger than
4GiB).

Regards,
Martin

Martin v. Loewis

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Feb 11, 2011, 3:54:25 PM2/11/11
to Craig Yoshida, Python list
Am 11.02.2011 19:41, schrieb Craig Yoshida:

In addition to the limitations Michel reports: on a 32-bit system,

Sherm Pendley

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Feb 11, 2011, 4:50:23 PM2/11/11
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IIRC, 32-bit Windows programs are limited to 2GiB, reserving the rest
of the virtual address space for Windows' own use.

Also, 32-bit apps remain 32-bit, even if they're running on a 64-bit
capable OS. Assuming you're running Snow Leopard on your Mac, you're
using a 64-bit Python interpreter *and* a 64-bit OS. You need to have
both to take advantage of a 64-bit memory space.

sherm--

--
Sherm Pendley
<http://camelbones.sourceforge.net>
Cocoa Developer

MRAB

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Feb 11, 2011, 7:27:36 PM2/11/11
to pytho...@python.org
On 11/02/2011 21:50, Sherm Pendley wrote:
> "Martin v. Loewis"<mar...@v.loewis.de> writes:
>
>> Am 11.02.2011 19:41, schrieb Craig Yoshida:
>>> what kind of memory limitations to processes running on 32-bit python
>>> (with 32-bit C extensions like scipy) have on 64-bit Windows? I'm
>>> having occasional MemoryErrors when running a python program on
>>> 64-bit Windows 7 that runs fine on my OS X machine. Both machines
>>> are using a 64-bit OS and have 4GB of RAM.
>>
>> In addition to the limitations Michel reports: on a 32-bit system,
>> objects are typically limited to using at most 2GiB, per object
>> (of course, you could have at most two objects that come close to
>> this size, since the whole address space would not be larger than
>> 4GiB).
>
> IIRC, 32-bit Windows programs are limited to 2GiB, reserving the rest
> of the virtual address space for Windows' own use.
>
It's possible to configure 32-bit Windows to allow up to 3GB user RAM.
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