[Zope-dev] SVN: Zope/trunk/ Optimized the `OFS.Traversable.getPhysicalPath` method to avoid excessive amounts of method calls. Thx to Nikolay Kim from Enfold

[Tres Seaver]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 07/14/2011 11:47 AM, Tres Seaver wrote:

> While we're at it, 'list.insert(0,foo)' is known to be slower in a
> tight loop than 'list.append(foo)', with a 'reversed' at the end of
> the loop::
> 
> $ python -m timeit -s "from string import letters" "path = []" \ "for
> letter in letters: path.append(letter)" \ "result =
> tuple(reversed(path))" 100000 loops, best of 3: 15.9 usec per loop
> 
> $ python -m timeit -s "from string import letters" "path = []" \ "for
> letter in letters: path.insert(0, letter)" \ "result = tuple(path)" 
> 10000 loops, best of 3:  25.3 usec per loop
> 
> 
> For the sake of comparison, the original tuple addition is actually 
> between the two:
> 
> $ python -m timeit -s "from string import letters" "result = ()" \ 
> "for letter in letters: result += (letter,)" 10000 loops, best of 3:
> 21.6 usec per loop

A further micro-optimization is to pre-allocate a big list in a thread
local.  Running the attached script produces::

 $ python perftest.py
 Via insert_0: 24.8401839733
 Via append: 15.6596238613
   speedup: 37.0%
 Via tuple_add: 21.9555268288
   speedup: 11.6%
 Via prealloc: 10.5278339386
   speedup: 57.6%



Tres.
- -- 
===================================================================
Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.10 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

iEYEARECAAYFAk4fIVAACgkQ+gerLs4ltQ6BlACguSHcHLWGjVIVJlQYIpL42RNc
mqMAn1Y16tyVmUkxd2ipNrZSeZpSFVEA
=oJJY
-----END PGP SIGNATURE-----
-------------- next part --------------
A non-text attachment was scrubbed...
Name: perftest.py
Type: application/x-httpd-cgi
Size: 1299 bytes
Desc: not available
Url : http://mail.zope.org/pipermail/zope-dev/attachments/20110714/67b06e7e/attachment.bin