| msg285574 - (view) |
Author: STINNER Victor (vstinner) *  |
Date: 2017-01-16 17:30 |
| Changes 27dc9a1c061e and 01b06ca45f64 converted the str (Unicode) methods to Argument Clinic, cool! But str methods taking more than one argument use positional-only arguments. Currently, Argument Clinic doesn't use METH_FASTCALL for these methods, but METH_VARARGS. There are two options: * Allow passing arguments as keywoards: str.replace(old='a', new='b') * Enhance Argument Clinic to use also METH_FASTCALL for functions using positional-only functions The goal is to speedup method calls. Example with str.replace(): $ ./python-patch -m perf timeit '"a".replace("x", "y")' --duplicate=100 --compare-to ./python-ref python-ref: ..................... 132 ns +- 1 ns python-patch: ..................... 102 ns +- 2 ns Median +- std dev: [python-ref] 132 ns +- 1 ns -> [python-patch] 102 ns +- 2 ns: 1.30x faster (-23%) |
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| msg285575 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-01-16 17:31 |
| Background: see also the old issue #17170 closed as rejected: "string method lookup is too slow". |
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| msg285576 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-01-16 17:32 |
| The issue #29263 "Implement LOAD_METHOD/CALL_METHOD for C functions" should also optimize C methods even more. |
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| msg285578 - (view) |
Author: Yury Selivanov (yselivanov) * |
Date: 2017-01-16 17:54 |
| > * Allow passing arguments as keywoards: str.replace(old='a', new='b') I think Guido explicitly stated that he doesn't like the idea to always allow keyword arguments for all methods. I.e. `str.find('aaa')` just reads better than `str.find(needle='aaa')`. Essentially, the idea is that for most of the builtins that accept one or two arguments, positional-only parameters are better. > * Enhance Argument Clinic to use also METH_FASTCALL for functions using positional-only functions So this is the option to go with. |
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| msg285581 - (view) |
Author: Serhiy Storchaka (serhiy.storchaka) * |
Date: 2017-01-16 18:52 |
| What is python-patch? |
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| msg285584 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-01-16 20:00 |
| > What is python-patch? It's Python patched with attached unicode_allow_kw.patch: allow to pass parameters as keywords for Unicode methods. |
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| msg285587 - (view) |
Author: Inada Naoki (methane) * |
Date: 2017-01-16 23:24 |
| Parsing positional arguments for METH_KEYWORDS and METH_FASTCALL can be faster by http://bugs.python.org/issue29029 |
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| msg285594 - (view) |
Author: Inada Naoki (methane) * |
Date: 2017-01-17 00:09 |
| This patch makes AC produces more FASTCALL instead of VARARGS. When looking AC output, one downside is it produces many consts like: + static const char * const _keywords[] = {"", "", "", "", "", NULL}; |
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| msg285595 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-01-17 01:10 |
| ac_more_fastcalls.patch: Hum, I guess that your change on _PyStack_UnpackDict() is related to a bug in the function prototype. The function is unable to report failure if args is NULL. It changed the API in the change 38ab8572fde2. |
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| msg285596 - (view) |
Author: Roundup Robot (python-dev)  |
Date: 2017-01-17 01:17 |
| New changeset d07fd6e6d449 by Victor Stinner in branch 'default': Rename _PyArg_ParseStack to _PyArg_ParseStackAndKeywords https://hg.python.org/cpython/rev/d07fd6e6d449 New changeset 01c57ef1b651 by Victor Stinner in branch 'default': Add _PyArg_ParseStack() helper function https://hg.python.org/cpython/rev/01c57ef1b651 New changeset 8bfec37ea86a by Victor Stinner in branch 'default': Add _PyArg_NoStackKeywords() helper function https://hg.python.org/cpython/rev/8bfec37ea86a New changeset 38ab8572fde2 by Victor Stinner in branch 'default': _PyStack_UnpackDict() now returns -1 on error https://hg.python.org/cpython/rev/38ab8572fde2 New changeset de90f3d06bc9 by Victor Stinner in branch 'default': Argument Clinic: Use METH_FASTCALL for positionals https://hg.python.org/cpython/rev/de90f3d06bc9 New changeset dea8922751a1 by Victor Stinner in branch 'default': Run Argument Clinic: METH_VARARGS=>METH_FASTCALL https://hg.python.org/cpython/rev/dea8922751a1 |
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| msg285597 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-01-17 01:37 |
| Naoki> This patch makes AC produces more FASTCALL instead of VARARGS. Oh, funny, I wrote the same patch :-) (almost) > When looking AC output, one downside is it produces many consts like: > + static const char * const _keywords[] = {"", "", "", "", "", NULL}; Yeah, I got the same result. I tried to hack a _PyArg_ParseStack() function which doesn't take keyword argments (no kwnames), but I lost my mind in parser_init(). So I decided to simply rebase my old patches from my random CPython fastcall forks to add a simple _PyArg_ParseStack(). My implementation doesn't use the super-fast _PyArg_Parser object, but at least it allows to use METH_FASTCALL. Compared to what we had previously (METH_VARARGS), it is an enhancement :-) I prefer to move step by step, since each commit is already big enough. It's also easier for me to maintain my forks if I push more changes upstream. So there is still room for improvement in _PyArg_ParseStack(), but I suggest to defer further optimizations to a new issue. |
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| msg285599 - (view) |
Author: Roundup Robot (python-dev) |
Date: 2017-01-17 01:48 |
| New changeset 3bf78c286daf by Victor Stinner in branch 'default': Add _PyArg_UnpackStack() function helper https://hg.python.org/cpython/rev/3bf78c286daf New changeset 905e902bd47e by Victor Stinner in branch 'default': Argument Clinic: Use METH_FASTCALL for boring positionals https://hg.python.org/cpython/rev/905e902bd47e New changeset 52acda52b353 by Victor Stinner in branch 'default': Run Argument Clinic: METH_VARARGS=>METH_FASTCALL https://hg.python.org/cpython/rev/52acda52b353 |
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| msg285600 - (view) |
Author: Roundup Robot (python-dev) |
Date: 2017-01-17 02:25 |
| New changeset d07fd6e6d449 by Victor Stinner in branch 'default': Rename _PyArg_ParseStack to _PyArg_ParseStackAndKeywords https://hg.python.org/cpython/rev/d07fd6e6d449 New changeset 01c57ef1b651 by Victor Stinner in branch 'default': Add _PyArg_ParseStack() helper function https://hg.python.org/cpython/rev/01c57ef1b651 New changeset 8bfec37ea86a by Victor Stinner in branch 'default': Add _PyArg_NoStackKeywords() helper function https://hg.python.org/cpython/rev/8bfec37ea86a New changeset 38ab8572fde2 by Victor Stinner in branch 'default': _PyStack_UnpackDict() now returns -1 on error https://hg.python.org/cpython/rev/38ab8572fde2 New changeset de90f3d06bc9 by Victor Stinner in branch 'default': Argument Clinic: Use METH_FASTCALL for positionals https://hg.python.org/cpython/rev/de90f3d06bc9 New changeset dea8922751a1 by Victor Stinner in branch 'default': Run Argument Clinic: METH_VARARGS=>METH_FASTCALL https://hg.python.org/cpython/rev/dea8922751a1 |
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| msg285614 - (view) |
Author: Serhiy Storchaka (serhiy.storchaka) * |
Date: 2017-01-17 06:24 |
| Oh, I have wrote almost the same patch before going to sleep yesteday! ;) But the building crashed (likely due to a bug in _PyStack_UnpackDict()) and it was too late to resolve this. I would prefer to rename "l" to "nargs" in PyArg_UnpackStack_impl and don't use upper case and namespace prefix in static functions. |
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| msg286647 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-02-01 16:36 |
| Recently, I saw complains that I push changes too fast without reviews. This issue is a good example. So let me elaborate myself a little bit on these changes. I'm not really proud of the "Rename _PyArg_ParseStack to _PyArg_ParseStackAndKeywords" change. It should be called _PyArg_ParseStackAndKeywords() from the beginning, but when I designed FASTCALL, my plan was to only check arguments (positional and keyword arguments) in the callee, and remove checks in the caller. I expected that all functions will get positional + keyword arguments. I didn't know that not accepting keywords but only positional arguments like in str.replace(), was a deliberate language design choice. So yes, for functions accepting only positional arguments, _PyArg_ParseStack() + _PyArg_NoStackKeywords() makes sense. IMHO the implementation of the new _PyArg_ParseStack() and _PyArg_NoStackKeywords() functions was simple enough to avoid a review, they reuse existing code with minimum changes. In general for FASTCALL, I only add private functions. I consider that it's ok to push code quickly, since the private property allows us to change these functions anytime. Again, I consider that the "Argument Clinic: Use METH_FASTCALL for positionals" change is simple enough to avoid a review, I don't think that they are many ways to use FASTCALL for functions using positional-only parameters. I mean, I only see a single way to implement it. Again, if someone sees a new way to handle such parameters, we can change it anytime, Argument Clinic and FASTCALL are stil private. More generally, FASTCALL requires a lot of tiny changes everywhere. GitHub will allow to get reviews on long patch series. It will be easier to handle large changes. |
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| msg286648 - (view) |
Author: Roundup Robot (python-dev) |
Date: 2017-02-01 16:42 |
| New changeset 758674087b12 by Victor Stinner in branch 'default': Issue #29286: Rename private PyArg_UnpackStack_impl() to unpack_stack() https://hg.python.org/cpython/rev/758674087b12 |
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| msg286649 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-02-01 16:43 |
| Serhiy Storchaka: "Oh, I have wrote almost the same patch before going to sleep yesteday! ;) But the building crashed (likely due to a bug in _PyStack_UnpackDict()) and it was too late to resolve this." Oh, sorry that you wrote almost the same code. Well, at least it means that we agree on the design :-) Serhiy: "I would prefer to rename "l" to "nargs" in PyArg_UnpackStack_impl and don't use upper case and namespace prefix in static functions." Done. |
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| msg286650 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-02-01 16:45 |
| str type still has a few methods using METH_VARARGS (slower than METH_FASTCALL): * count() * find() * index() * rfind() * rindex() * startswith() * endswith() * format() Maybe I will propose a change later to convert these methods to Argument Clinic, but I consider that the initial issue "Currently, Argument Clinic doesn't use METH_FASTCALL for these methods, but METH_VARARGS" is now fixed, so I close the issue. Thanks Naoki and Serhiy. |
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| msg286653 - (view) |
Author: Roundup Robot (python-dev) |
Date: |
| New changeset 5910fd7231d34363798d2815be2f66909e638d1c by Victor Stinner in branch 'master': Issue #29286: Rename private PyArg_UnpackStack_impl() to unpack_stack() https://github.com/python/cpython/commit/5910fd7231d34363798d2815be2f66909e638d1c |
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| msg295516 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2017-06-09 11:24 |
| New changeset f0ff849adc6b4a01f9d1f08d9ad0f1511ff84541 by Victor Stinner in branch '3.6': bpo-30524: Fix _PyStack_UnpackDict() (#1886) https://github.com/python/cpython/commit/f0ff849adc6b4a01f9d1f08d9ad0f1511ff84541 |
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