[issue5109] array.array constructor very slow when passed an array object.

[Malcolm Purvis]

New submission from Malcolm Purvis <malcolm at purvis.id.au>:

Copying an array.array object via the array constructor is some 100x
slower than using slicing or even converting the array to a string and
then passing that string to the array constructor.

Running the attached program on a 2.2GHz MacBook Pro (OSX 10.5.5, 4GB
RAM) produces this output:

$ python2.6 array_test.py
Constructor:  18.5617749691
Slice:  0.169251918793
String:  0.375015974045

>From a look at arraymodule.c it seems that array_new() does not have a
special case for the array type and therefore uses the generic sequence
copy code rather than using memcpy(), like it can for slicing.

----------
components: Library (Lib)
files: array_test.py
messages: 80815
nosy: malcolmp
severity: normal
status: open
title: array.array constructor very slow when passed an array object.
type: performance
versions: Python 2.6
Added file: http://bugs.python.org/file12893/array_test.py

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<http://bugs.python.org/issue5109>
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