[Numpy-discussion] A memory problem: why does mmap come up in numpy.inner?

Charles R Harris charlesr.harris@gmail....
Wed Jun 4 22:18:25 CDT 2008


Hi Dan,

On Wed, Jun 4, 2008 at 8:50 PM, Dan Yamins <dyamins@gmail.com> wrote:

>
>
>
>
>> Try
>>
>> In [3]: numpy.dtype(numpy.uintp).itemsize
>> Out[3]: 4
>>
>> which is the size in bytes of the integer needed to hold a pointer. The
>> output above is for 32 bit python/numpy.
>>
>> Chuck
>>
>
> Check, the answer is 4, as you got for the 32-bit.   What would the answer
> be on a 64-bit architecture?  Why is this diagnostic?
>

On 64 bit ubuntu

In [1]: import numpy

In [2]: numpy.dtype(numpy.uintp).itemsize
Out[2]: 8


This is diagnostic because a pointer of 4 bytes, 32 bits, can only address 4
GiB whereas an 8 byte pointer has 64 bits to address memory. So it looks
like your numpy was compiled by a 32 python executable.

I've been been googling this a bit and it looks like the standard executable
python on the mac is 32 bits, even though 64 bit libraries are available if
you can get a 64 bit version up and running. A lot of libraries are
available in both 32 and 64 bit versions.

Chuck

>
> Thanks!
> Dan
>
>
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