Hi, 
 I make a little change in the urlsplit function of urlparse module. And
the performance when I'm parsing a lot of urls was improved a bit.
In the best case was improved around a 20% percent.

Python version:
2.5.2 (r252:60911, Oct  5 2008, 19:29:17) 
[GCC 4.3.2]

Here are the benchmarks:
#:~/tests$ python profile_urlparse.py 
timing urlparse.urlparse():
    [0.28006601333618164, 0.27513313293457031, 0.20408511161804199]
timing myurlparse.urlparse():
    [0.11000704765319824, 0.10729002952575684, 0.10677695274353027]
#:~/tests$ python profile_urlparse2.py 
timing urlparse.urlparse():
    [0.28334403038024902, 0.27912592887878418, 0.15959692001342773]
timing myurlparse.urlparse():
    [0.11277103424072266, 0.11163187026977539, 0.11175107955932617]
#:~/tests$ python profile_urlparse2.py 
timing urlparse.urlparse():
    [0.28750920295715332, 0.2779538631439209, 0.27816200256347656]
timing myurlparse.urlparse():
    [0.25010085105895996, 0.11236691474914551, 0.11198592185974121]


#-- Paste here the profiling code -----------
#-- Please rename the file as : profile_urlparse.py

urls = [
   
"http://www.notonthehighstreet.com/boxwood/product/dotty_picture_frames",
    "http://www.fancylighting.com/acatalog/Petrushka_Bronze.html",
   
"http://cgi.ebay.co.uk/3-LITRE-SUNNEX-STAINLESS-STEEL-TEAPOT-COFFEE-POT_W0QQitemZ160230173283QQcategoryZ122942QQcmdZViewItem",
   
"http://retail.ictc.co.uk/acatalog/Online_Catalogue__Homegrown_184.html",
   
"http://www.amazon.co.uk/Big-Mog-Tape-Judith-Kerr/dp/0001025252?SubscriptionId=0QE3E4F7T4Q5DCSKG202&tag=ws&linkCode=xm2&camp=2025&creative=165953&creativeASIN=0001025252",
   
"http://www.dinerstore.co.uk/acatalog/copy_of_Bedford_Oak_Table_and_Six.html",
   
"http://www.panik-design.co.uk/acatalog/Iittala_-_A_Citterio_-_Citterio_98_Cutlery_24pcs_.html",
    "http://www.johnlewis.com/230544027/Product.aspx",
   
"http://cgi.ebay.co.uk/Damask-Black-Pink-Cream-Large-Modern-Rugs-120x170cm_W0QQitemZ400021540458QQcategoryZ57237QQcmdZViewItem",
   
"http://www.amazon.co.uk/Nikon-50Mm-F1-2-Nikkor-Lens/dp/B00009R95Y?SubscriptionId=0QE3E4F7T4Q5DCSKG202&tag=ws&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B00009R95Y",
   
"http://www.amazon.co.uk/Storeys-Guide-Raising-Llamas-Birutta/dp/1580173284?SubscriptionId=0QE3E4F7T4Q5DCSKG202&tag=ws&linkCode=xm2&camp=2025&creative=165953&creativeASIN=1580173284",
    "http://www.24electric.com/detail.php?ProdID=46519663",
   
"http://cgi.ebay.co.uk/Antique-Pine-Midi-Sleeper-Childrens-Bed-VGC_W0QQitemZ280285887713QQcategoryZ122763QQcmdZViewItem",
    "http://www.johnlewis.com/230421907/Product.aspx",
   
"http://cgi.ebay.co.uk/WICKER-PLACE-DINNER-MATS-X6-IN-A-WICKER-BASKET-WITH-LID_W0QQitemZ350141392941QQcategoryZ20660QQcmdZViewItem",
   
"http://www.trueshopping.co.uk/product/Draper_1_4_Square_Drive_Reversible_Ratchet/3495/43235.html",
   
"http://www.amazon.co.uk/Transcend-TS128MIB6986-128MB-Module/dp/B000HCO61K?SubscriptionId=0QE3E4F7T4Q5DCSKG202&tag=ws&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B000HCO61K",
   
"http://www.unitedinteriors.co.uk/regency-pine-hi-fi-cabinet-4741-p.asp",
   
"http://www.amazon.co.uk/BATTERY-CAMCORDER-DCR-DVD602-DCR-DVD602E-DCRDVD602/dp/B0017UM1OU?SubscriptionId=0QE3E4F7T4Q5DCSKG202&tag=ws&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B0017UM1OU",
    "http://www.tooled-up.com/Product.asp?PID=145138",
   
"http://www.dinerstore.co.uk/acatalog/copy_of_Bedford_Oak_Table_and_Six.html",
   
"http://www.panik-design.co.uk/acatalog/Iittala_-_A_Citterio_-_Citterio_98_Cutlery_24pcs_.html",
    "http://www.johnlewis.com/230544027/Product.aspx",
   
"http://cgi.ebay.co.uk/Damask-Black-Pink-Cream-Large-Modern-Rugs-120x170cm_W0QQitemZ400021540458QQcategoryZ57237QQcmdZViewItem",
   
"http://www.amazon.co.uk/Nikon-50Mm-F1-2-Nikkor-Lens/dp/B00009R95Y?SubscriptionId=0QE3E4F7T4Q5DCSKG202&tag=ws&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B00009R95Y",
   
"http://www.amazon.co.uk/Storeys-Guide-Raising-Llamas-Birutta/dp/1580173284?SubscriptionId=0QE3E4F7T4Q5DCSKG202&tag=ws&linkCode=xm2&camp=2025&creative=165953&creativeASIN=1580173284",
    "http://www.24electric.com/detail.php?ProdID=46519663",
   
"http://cgi.ebay.co.uk/Antique-Pine-Midi-Sleeper-Childrens-Bed-VGC_W0QQitemZ280285887713QQcategoryZ122763QQcmdZViewItem",
    "http://www.johnlewis.com/230421907/Product.aspx",
   
"http://cgi.ebay.co.uk/WICKER-PLACE-DINNER-MATS-X6-IN-A-WICKER-BASKET-WITH-LID_W0QQitemZ350141392941QQcategoryZ20660QQcmdZViewItem",
   
"http://www.trueshopping.co.uk/product/Draper_1_4_Square_Drive_Reversible_Ratchet/3495/43235.html",
]

if __name__ == '__main__':
    import sys
    import timeit

    if len(sys.argv) > 1:
        times = int(sys.argv[1])
    else:
        times = 1000

    t = timeit.Timer("[urlparse.urlparse(u) for u in urls]", 
                     "from profile_urlparse import urls; import urlparse")
    print "timing urlparse.urlparse():"
    print "   ", t.repeat(3, times)


    t = timeit.Timer("[myurlparse.urlparse(u) for u in urls]", 
                     "from profile_urlparse import urls; import myurlparse")
    print "timing myurlparse.urlparse():"
    print "   ", t.repeat(3, times)

#--- End of profile code ----------------------------------------

It looks like most of your changes are already part of urlparse module 
of Python 2.6. Can you port your patch to Python 2.6 and retry your 
benchmark on Python 2.6?

Hi haypo,
 Ok I've been testing with python 2.6 and I put the results here:
 optimizedurlparse is the file with my patch

 First test optimizedurlparse, second urlparse:

#:/opt/python2.6/release26-maint$ ./python mio/profile_urlparse.py 
timing optimizedurlparse.urlparse():
    [0.89634895324707031, 0.61937308311462402, 0.62004208564758301]
timing urlparse.urlparse():
    [0.64083003997802734, 0.6862800121307373, 0.67195010185241699]

#:/opt/python2.6/release26-maint$ ./python mio/profile_urlparse.py 2000
timing optimizedurlparse.urlparse():
    [1.5077390670776367, 1.2391939163208008, 1.2390918731689453]
timing urlparse.urlparse():
    [1.2550511360168457, 1.2493829727172852, 1.2445049285888672]

Now I'll change the order of execution, first urlparse , second
optimizedurlparse:

#:/opt/python2.6/release26-maint$ ./python mio/profile_urlparse.py 2000
timing urlparse.urlparse():
    [1.6836080551147461, 1.3892900943756104, 1.3195438385009766]
timing optimizedurlparse.urlparse():
    [1.4834678173065186, 1.4077410697937012, 1.3824198246002197]
[19647 refs]
#:/opt/python2.6/release26-maint$ ./python mio/profile_urlparse.py 2000
timing urlparse.urlparse():
    [1.4398901462554932, 1.3237769603729248, 1.3057329654693604]
timing optimizedurlparse.urlparse():
    [1.3134419918060303, 1.3127460479736328, 1.2928199768066406]
[19647 refs]

Python Version: 
2.6.1+ (release26-maint:68606, Jan 14 2009, 08:48:41)

The small changes optimize the urlparse.urlparse and urlsplit function a
bit :D.

Please, attach patches instead of the full file.

And that is the profile code.

Hi haypo, 
 sorry for submit all the file, it's my first time here and I'm not very
used to this process yet. :)
Now I attach the patch.

> Now I attach the patch.

Your first patch for Python 2.5 was interesting, and looked close to the 
python 2.6 version. But your second patch (for 2.6) contains only 
micro-optimisations:
 - inline the one-line clear_cache() function
 - replace "scheme, url = ..." assignation (used for scheme different 
   than http) by classic assignation (url = ...)

Your benchmark numbers are difficult to read, but I can't see impressive 
results (I guess it's smaller than 10%, maybe 5%).

Yes are micro-optimizations, but when I parsed a lot of url(10.000 or
more) that 10% or 8% or 5% is very well for me :). It was little
contribution to that module, anyway, i think that there are more
optimizatoins to do but I will try to do it then.

Andres, do you wish to provide more patches or can we close this issue?

I reviewed the patch and we may not go with it.
- There is recent improvements in parsing and the patch does not go well with it, especially the clear_cache removal.

Also there is a mistake in the patch:

-            scheme, url = url[:i].lower(), url[i+1:]
+            url = url[i+1:]

This can create problems for certain parsing logic as scheme is being used later in the code.

Closing the bug is invalid.