[issue10181] Problems with Py_buffer management in memoryobject.c (and elsewhere?)

[Stefan Krah]

Stefan Krah <stefan-usenet at bytereef.org> added the comment:

Pauli Virtanen <report at bugs.python.org> wrote:
> Comment on the patch: it seems you do not track the re-export count in memory_getbuf:
> 
>     a = memoryview(obj)
>     b = numpy.asarray(a)
>     a.release()
>     b[0] = 123 # <-- BOOM: the buffer was already released

Could you give the exact sequence of events (including the creation of obj)?

For me this works:

Python 3.3a0 (memoryview:bbe70ca4e0e5+, Jul  4 2011, 13:55:55) 
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy
>>> obj = bytearray(b'123456789')
>>> a = memoryview(obj)
>>> b = numpy.asarray(a)
>>> a.release()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
BufferError: several memoryviews are active
>>> b[0] = 123
>>> b
array([123,  50,  51,  52,  53,  54,  55,  56,  57], dtype=uint8)
>>> del a
>>> b[0] = 224
>>> b
array([224,  50,  51,  52,  53,  54,  55,  56,  57], dtype=uint8)

> (I had some code for n-dim slicing etc. in my first patch that could be
>  useful to have too; I'll see if I find time to dig them out here.)

That would be nice.

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<http://bugs.python.org/issue10181>
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