[Numpy-discussion] Windows/numpy1.0.4 memmap & astype produce loads of warnings on delete

Robert Kern robert.kern@gmail....
Thu Apr 17 03:21:12 CDT 2008


On Thu, Apr 17, 2008 at 3:10 AM, Wim Bakker <bakker@itc.nl> wrote:
> The last version of numpy gives me headaches. I've been able to trace
>  the problem to the use of astype(). When a memmap is deleted I get the
>  following warning:
>
>  Exception exceptions.ValueError: 'mmap closed or invalid' in <bound
>  method memmap.__del__ of memmap([ 0.,  1.,  2.,  3.,  4.,  5.,  6.,  7.,
>  8.,  9.])> ignored
>
>  The memmap still seems to work but these error messages slow don't the
>  processing considerably. When reverting back to numpy 1.0.2 the problem
>  disappears.
>
>  Below is a short program that reproduces the warnings:
>
>  ==
>  import numpy
>
>  a = numpy.memmap(r'C:\Temp\test.dat', mode='w+', shape=(10,), dtype='b')
>
>  for i in range(10):
>     a[i] = i
>
>  del a
>
>  a = numpy.memmap(r'C:\Temp\test.dat', mode='r', shape=(10,), dtype='b')
>
>  a = a.astype('d')
>
>  del a
>  ==
>
>  The last delete produces the warnings.
>
>  Am I doing something wrong or should this be fixed in numpy?

I think I or someone else fixed most of these issues in SVN. Can you
try out SVN numpy and see if the warnings are gone in your code? I
don't see them on OS X.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
 -- Umberto Eco


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