[Numpy-discussion] Memmap with multiprocessing

Ralf Gommers ralf.gommers at googlemail.com
Tue Apr 26 17:21:03 EDT 2011


On Mon, Apr 25, 2011 at 1:16 PM, Thiago Franco Moraes
<totonixsame at gmail.com> wrote:
> Hi,
>
> Has anyone confirmed if this is a bug? Should I post this in the bug tracker?

I see the same thing with recent master. Something very strange is
going on in the memmap.__array_finalize__ method under Windows. Can
you file a bug?

Ralf


>
> Thanks!
>
> On Tue, Apr 19, 2011 at 9:01 PM, Thiago Franco de Moraes
> <totonixsame at gmail.com> wrote:
>> Hi all,
>>
>> I'm having a error using memmap objects shared among processes created
>> by the multprocessing module. This error only happen in Windows with
>> numpy 1.5 or above, in numpy 1.4.1 it doesn't happen, In Linux and Mac
>> OS X it doesn't happen. This error is demonstrated by this little
>> example script here https://gist.github.com/929168 , and the traceback
>> is bellow (between <traceback> tags):
>>
>> <traceback>
>> Process Process-1:
>> Traceback (most recent call last):
>>  File "C:\Python26\Lib\multiprocessing\process.py", line 232, in _bootstrap
>>    self.run()
>>  File "C:\Python26\Lib\multiprocessing\process.py", line 88, in run
>>    self._target(*self._args, **self._kwargs)
>>  File "C:\Documents and Settings\phamorim\Desktop\test.py", line 7, in
>> print_ma
>> trix
>>    print matrix
>>  File "C:\Python26\Lib\site-packages\numpy\core\numeric.py", line 1379, in
>> arra
>> y_str
>>    return array2string(a, max_line_width, precision, suppress_small, ' ',
>> "", s
>> tr)
>>  File "C:\Python26\Lib\site-packages\numpy\core\arrayprint.py", line 309, in
>> ar
>> ray2string
>>    separator, prefix)
>>  File "C:\Python26\Lib\site-packages\numpy\core\arrayprint.py", line 189, in
>> _a
>> rray2string
>>    data = _leading_trailing(a)
>>  File "C:\Python26\Lib\site-packages\numpy\core\arrayprint.py", line 162, in
>> _l
>> eading_trailing
>>    min(len(a), _summaryEdgeItems))]
>>  File "C:\Python26\Lib\site-packages\numpy\core\memmap.py", line 257, in
>> __arra
>> y_finalize__
>>    self.filename = obj.filename
>> AttributeError: 'memmap' object has no attribute 'filename'
>> Exception AttributeError: AttributeError("'NoneType' object has no attribute
>> 'te
>> ll'",) in <bound method memmap.__del__ of memmap([0, 0, 0, 0, 0, 0, 0, 0, 0,
>> 0,
>> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
>>       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
>>       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
>>       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
>>       0, 0, 0, 0, 0, 0, 0, 0], dtype=int16)> ignored
>> </traceback>
>>
>> I don't know if it's a bug, but I thought it's is import to report
>> because the version 1.4.1 was working and 1.5.0 and above was not.
>>
>> Thanks!
>>
>>
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