Created on 2013-10-23 19:38 by pitrou, last changed 2013-10-24 20:21 by serhiy.storchaka. This issue is now closed.
| Files | ||||
|---|---|---|---|---|
| File name | Uploaded | Description | Edit | |
| lengthhint.patch | pitrou, 2013-10-23 19:40 | review | ||
| lengthhint_2.patch | serhiy.storchaka, 2013-10-23 21:43 | review | ||
| Messages (7) | |||
|---|---|---|---|
| msg201060 - (view) | Author: Antoine Pitrou (pitrou) *  |
Date: 2013-10-23 19:38 | |
PyObject_LengthHint is in the critical patch for many operations (such as list constructor, or list.extend), but it's quite unoptimized. |
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| msg201061 - (view) | Author: Antoine Pitrou (pitrou) * |
Date: 2013-10-23 19:40 | |
Here is a patch. Micro-benchmark: $ ./python -m timeit -s "l=[]; it=(x for x in ())" "l.extend(it)" -> before: 0.449 usec per loop -> after: 0.179 usec per loop |
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| msg201066 - (view) | Author: Serhiy Storchaka (serhiy.storchaka) * |
Date: 2013-10-23 20:23 | |
What if use _PyObject_HasLen?
if (_PyObject_HasLen(o)) {
res = PyObject_Length(o);
...
}
hint = _PyObject_LookupSpecial(o, &PyId___length_hint__);
...
|
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| msg201071 - (view) | Author: Serhiy Storchaka (serhiy.storchaka) * |
Date: 2013-10-23 21:43 | |
Here is a patch which uses _PyObject_HasLen. It has same performance but is much simpler. |
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| msg201073 - (view) | Author: Antoine Pitrou (pitrou) * |
Date: 2013-10-23 21:49 | |
> Here is a patch which uses _PyObject_HasLen. It has same performance > but is much simpler. Thanks! |
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| msg201155 - (view) | Author: Raymond Hettinger (rhettinger) * |
Date: 2013-10-24 16:33 | |
> Here is a patch which uses _PyObject_HasLen. It has same performance > but is much simpler. +1 This will be a nice improvement. |
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| msg201181 - (view) | Author: Roundup Robot (python-dev) | Date: 2013-10-24 20:20 | |
New changeset bffb49efc383 by Serhiy Storchaka in branch 'default': Issue #19369: Optimized the usage of __length_hint__(). http://hg.python.org/cpython/rev/bffb49efc383 |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2013-10-24 20:21:55 | serhiy.storchaka | set | status: open -> closed resolution: fixed stage: resolved |
| 2013-10-24 20:20:18 | python-dev | set | nosy:
+ python-dev messages: + msg201181 |
| 2013-10-24 20:14:58 | serhiy.storchaka | set | assignee: serhiy.storchaka |
| 2013-10-24 16:33:17 | rhettinger | set | messages: + msg201155 |
| 2013-10-23 21:49:30 | pitrou | set | messages: + msg201073 |
| 2013-10-23 21:43:58 | serhiy.storchaka | set | files:
+ lengthhint_2.patch messages: + msg201071 |
| 2013-10-23 20:23:45 | serhiy.storchaka | set | nosy:
+ serhiy.storchaka messages: + msg201066 |
| 2013-10-23 19:40:47 | pitrou | set | files:
+ lengthhint.patch keywords: + patch messages: + msg201061 |
| 2013-10-23 19:38:27 | pitrou | create | |