Created on 2019-10-28 11:55 by methane, last changed 2019-11-07 15:59 by methane. This issue is now closed.
| Pull Requests | |||
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| URL | Status | Linked | Edit |
| PR 16961 | merged | methane, 2019-10-28 11:57 | |
| Messages (7) | |||
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| msg355536 - (view) | Author: Inada Naoki (methane) *  |
Date: 2019-10-28 11:55 | |
-, |, and ^ of dictkeys are implemented as:
PyObject *result = PySet_New(self);
// Call set.difference_update, set.update, set.symmetric_difference_update with other.
PySet_New(iterable) has optimized step for iterable is dict.
But since iterable is dictkeys, PyIter_Next() is called for all elements in the dict.
We can pass dict instead of dictkey object to PySet_New.
$ ./python -m pyperf timeit -o patched.json -s 'k = dict.fromkeys("abcdefghijklmnopqrstuvwxyz").keys(); s={1,2,3}' -- 'k | {1,2,3}'
$ ./python -m pyperf compare_to master.json patched.json
Mean +- std dev: [master] 778 ns +- 17 ns -> [patched] 550 ns +- 24 ns: 1.42x faster (-29%)
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| msg355541 - (view) | Author: Serhiy Storchaka (serhiy.storchaka) * |
Date: 2019-10-28 13:33 | |
How does it work with dict subclasses? |
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| msg355618 - (view) | Author: Inada Naoki (methane) * |
Date: 2019-10-29 06:20 | |
> How does it work with dict subclasses? PySet_New(iterable) uses fast path only when `PyDict_CheckExact(iterable)` is true. So there is no change for dict subclasses. |
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| msg355619 - (view) | Author: Serhiy Storchaka (serhiy.storchaka) * |
Date: 2019-10-29 06:45 | |
But what if a dict subclass overrides __iter__? You can get different result if set(d) != set(d.keys()). |
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| msg355662 - (view) | Author: Raymond Hettinger (rhettinger) * |
Date: 2019-10-29 16:29 | |
Consider testing PyDict_CheckExact. |
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| msg355695 - (view) | Author: Inada Naoki (methane) * |
Date: 2019-10-30 07:39 | |
done. |
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| msg356195 - (view) | Author: Inada Naoki (methane) * |
Date: 2019-11-07 15:59 | |
New changeset 6cbc84fb99acb33dd659d7adb29a20adbe62b74a by Inada Naoki in branch 'master': bpo-38613: Optimize set operations of dict keys. (GH-16961) https://github.com/python/cpython/commit/6cbc84fb99acb33dd659d7adb29a20adbe62b74a |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2019-11-07 15:59:26 | methane | set | status: open -> closed resolution: fixed stage: patch review -> resolved |
| 2019-11-07 15:59:10 | methane | set | messages: + msg356195 |
| 2019-10-30 07:39:49 | methane | set | messages: + msg355695 |
| 2019-10-29 16:29:45 | rhettinger | set | nosy:
+ rhettinger messages: + msg355662 |
| 2019-10-29 06:45:21 | serhiy.storchaka | set | messages: + msg355619 |
| 2019-10-29 06:20:01 | methane | set | messages: + msg355618 |
| 2019-10-28 13:33:42 | serhiy.storchaka | set | nosy:
+ serhiy.storchaka messages: + msg355541 |
| 2019-10-28 11:57:25 | methane | set | keywords:
+ patch stage: patch review pull_requests: + pull_request16489 |
| 2019-10-28 11:55:45 | methane | create | |