classification
Title: Optimize list iteration
Type: Stage:
Components: Interpreter Core Versions: Python 2.3
process
Status: closed Resolution: accepted
Dependencies: Superseder:
Assigned To: rhettinger Nosy List: gvanrossum, rhettinger (2)
Priority: normal Keywords patch

Created on 2002-05-26 15:25 by rhettinger, last changed 2002-05-31 21:38 by rhettinger.

Files
File name Uploaded Description Edit Remove
list.diff rhettinger, 2002-05-26 15:25 Patch to add list iterator
list2.diff rhettinger, 2002-05-31 21:07 Revised patch using PyList_Check()
Messages (5)
msg40134 - (view) Author: Raymond Hettinger (rhettinger) Date: 2002-05-26 15:25 
Filled listobject's tp_iter slot with it's own iterator.  
Speeds looping 5 to 10% (YMMV).

Only half of the speed-up comes from using tp_iter.  
The rest came from code tweaking:
-- eliminate the it variable
-- invert the limit test to avoid jumps
-- bypass the GET_ITEM macro to allow index++ to be 
combined with the lookup.
msg40135 - (view) Author: Guido van Rossum (gvanrossum) Date: 2002-05-31 18:07 
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user_id=6380

Very close. It looks like you are using PySequence_Check()
where you should be using PyList_Check() though, since
listiter_next() really needs it to be a list! (Two place
have this mistake.)

Apart from that, it's good! (Note that the speedup
percentage is better when you use -O. :-)
msg40136 - (view) Author: Raymond Hettinger (rhettinger) Date: 2002-05-31 21:07 
Logged In: YES 
user_id=80475

Replaced both instances with PyList_Check().
No other changes.
Re-verified compile, timings, and regression tests.

Okay to commit?
msg40137 - (view) Author: Guido van Rossum (gvanrossum) Date: 2002-05-31 21:28 
Logged In: YES 
user_id=6380

Go ahead, and then close this issue!
msg40138 - (view) Author: Raymond Hettinger (rhettinger) Date: 2002-05-31 21:38 
Logged In: YES 
user_id=80475

Committed as listobject.c 2.107 and iterobject.c 1.10

Closing patch.
History
Date User Action Args
2002-05-26 15:25:24rhettingercreate