showell added the comment:
My proposed test is final. Please either accept or reject it as is. I assume
it runs pretty quickly, so I am not sure what the cost fear is. The benefit of
accepting the test is that it would potentially catch bugs on changes to the
implementation of list
showell added the comment:
+1 on showing off remainder_near. I recently wrote a program where I
reinvented the logic (on a unit circle too), not knowing it was already
implemented in Decimal.
--
nosy: +Steve Howell
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Python tracker
<h
showell added the comment:
I am closing this due to mostly unanimous rejection on python-dev.
If folks reopen this in the future, the last patch that I submitted has been
reasonably well tested, but it has not been code reviewed.
The 1% speed penalty could probably be driven down without too
showell added the comment:
Per Ezio's suggestions, I added clearer comments and an assert, and now the
attached diff applies to trunk.
--
keywords: +patch
Added file: http://bugs.python.org/file16037/extend_test.diff
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Python tracker
Changes by showell :
Removed file: http://bugs.python.org/file16033/list_top_no_extra_mem.diff
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Python tracker
<http://bugs.python.org/issue7784>
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Python-bug
showell added the comment:
Ok, found the offending line, now all tests pass.
The use case where this patch will pay off the most is slicing your way through
a list of tasks. The toy program below gets about a 50x speedup.
import time
n = 80
lst
showell added the comment:
I am attaching a new patch that does not add a new element to PyListObject,
roughly following a technique that Antoine Pitrou suggested on python-dev.
When I want to lazily avoid a memmove under the new patch, I set the MSB on
allocated and store the original
showell added the comment:
I will attempt to fix insert(0, pop) in the next patch I submit (using pointer
vs. orphans count).
Just so we are clear on the performance that I'm promising, I expect benchmarks
to prove out these facts:
1) New-list will always perform comparably to old
showell added the comment:
The next stage for the patch is that I need to switch from using orphans count
to using ob_allocated pointer.
--
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Python tracker
<http://bugs.python.org/issue7
showell added the comment:
--- On Tue, 1/26/10, Florent Xicluna wrote:
> From: Florent Xicluna
> Subject: [issue7784] patch for making list/insert at the top of the list
> avoid memmoves
> To: showel...@yahoo.com
> Date: Tuesday, January 26, 2010, 3:53 AM
>
> Florent
New submission from showell :
I am attaching a patch to improve the performance of list operations that
insert or delete elements at the front of the list. The patch has had some
discussion on python-dev in the thread entitled "patch to make list.pop(0) work
in O(1) time."
New submission from showell :
I would like to submit the following test to be part of the test_iter.py test
suite:
def test_extends(self):
# This test would break on an incomplete patch to listobject.c
def gen():
for i in range(500):
yield i
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