Avoid temporary `varargs` tuple creation in argument passing #90370

colorfulappl · 2021-12-31T10:05:47Z

BPO	46212
Nosy	@larryhastings, @pablogsal, @isidentical, @erlend-aasland, @colorfulappl
PRs	gh-90370: Avoid temporary `varargs` tuple creation in argument passing #30312
Files	bench-print.py

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-12-31.10:05:47.113>
labels = ['3.11', 'expert-argument-clinic', 'performance']
title = 'Avoid temporary `varargs` tuple creation in argument passing'
updated_at = <Date 2022-01-21.14:06:02.177>
user = 'https://github.com/colorfulappl'

bugs.python.org fields:

activity = <Date 2022-01-21.14:06:02.177>
actor = 'erlendaasland'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Argument Clinic']
creation = <Date 2021-12-31.10:05:47.113>
creator = 'colorfulappl'
dependencies = []
files = ['50533']
hgrepos = []
issue_num = 46212
keywords = ['patch']
message_count = 6.0
messages = ['409412', '409413', '409414', '409659', '411129', '411130']
nosy_count = 5.0
nosy_names = ['larry', 'pablogsal', 'BTaskaya', 'erlendaasland', 'colorfulappl']
pr_nums = ['30312']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue46212'
versions = ['Python 3.11']

Linked PRs

gh-90370: avoid temporary tuple creation for vararg in AC #126064

The text was updated successfully, but these errors were encountered:

colorfulappl · 2021-12-31T10:05:47Z

When "Augument Clinic generated code" are parsing arguments, the args are packed to a tuple before passing to callee. This may be unnecessary.

Pass a raw pointer which points to on-stack varargs, and a varargssize integer to indicate how many varargs are passed, can save the time of tuple creation/destruction and value copy.

colorfulappl · 2021-12-31T10:18:08Z

I wrote some microbenchs.

Patch: b68176d

Environment:
macOS 12.1
clang 13.0.0
configure with --enable-optimizations

Result on microbench:

+--------------------------------------------+-------------------------+------------------------+
| Benchmark                                  | ./opt_baseline/res.json | ./opt_patched/res.json |
+============================================+=========================+========================+
| print(a, b, c)                             | 917 ns                  | 820 ns: 1.12x faster   |
+--------------------------------------------+-------------------------+------------------------+
| print(a, b, c, *v)                         | 1.56 us                 | 1.62 us: 1.04x slower  |
+--------------------------------------------+-------------------------+------------------------+
| print(a, sep='', file=stdout)              | 376 ns                  | 295 ns: 1.27x faster   |
+--------------------------------------------+-------------------------+------------------------+
| print(*v, sep='', flush=True, file=stdout) | 2.02 us                 | 1.94 us: 1.04x faster  |
+--------------------------------------------+-------------------------+------------------------+
| Geometric mean                             | (ref)                   | 1.05x faster           |
+--------------------------------------------+-------------------------+------------------------+

Benchmark hidden because not significant (3): print(a), print(a, sep='', flush=True, file=stdout), print(a, b, c, *v, sep='', flush=True, file=stdout)

erlend-aasland · 2021-12-31T11:04:47Z

Note that _PyArg_UnpackKeywordsWithVararg is defined with PyAPI_FUNC. Changing its argument spec is strictly a backwards incompatible change, IIUC.

colorfulappl · 2022-01-04T09:36:51Z

I am a rookie in Python, did not notice changing PyAPI_FUNC means breaking backward compatibility.

I have reverted _PyArg_UnpackKeywordsWithVararg and committed again.

isidentical · 2022-01-21T14:04:00Z

Note that _PyArg_UnpackKeywordsWithVararg is defined with PyAPI_FUNC. Changing its argument spec is strictly a backwards incompatible change, IIUC.

AFAIK we have committed _PyArg_UnpackKeywordsWithVararg on 3.11 alpha, so I think it should be fine. Also CC: @pablogsal

erlend-aasland · 2022-01-21T14:06:02Z

AFAIK we have committed _PyArg_UnpackKeywordsWithVararg on 3.11 alpha, so I think it should be fine.

I see, so no ABI worries then.

skirpichev · 2024-10-26T05:19:36Z

It seems #30312 was abandoned by author. I'll continue this work.

Current patch partially address issue, working in case when all arguments either positional-only or vararg. This also converts gcd(), lcm() and hypot() functions of the math module to the Argument Clinic. Fix issue python#101123. Objects/setobject.c and Modules/gcmodule.c adapted. This fixes slight performance regression for set methods, introduced by python#115112: | Benchmark | ref | patch | |----------------------|:------:|:--------------------:| | set().update(s1, s2) | 354 ns | 264 ns: 1.34x faster | Benchmark code: ```py import pyperf s1, s2 = {1}, {2} runner = pyperf.Runner() runner.bench_func('set().update(s1, s2)', set().update, s1, s2) ```

skirpichev · 2024-10-28T08:14:58Z

#126064 is ready for review (partially address issue)

…#126064) Avoid temporary tuple creation when all arguments either positional-only or vararg. Objects/setobject.c and Modules/gcmodule.c adapted. This fixes slight performance regression for set methods, introduced by gh-115112.

skirpichev · 2024-10-31T11:29:29Z

@erlend-aasland, I'm not sure we can mark this a fixed issue.

The merged pr covers only part of the original proposal (e.g. it doesn't work for the OP example with print()).

serhiy-storchaka · 2024-11-06T08:36:55Z

I planned to came to this issue in few steps:

Current gh-122943: Rework support of var-positional parameter in Argument Clinic #122945.
Move the code for var-positional parameter to a separate converter (this is not easy, because it needs more parameters).
Split that converter into two converters -- 'tuple' and 'array' to support different representations.

There may be other intermediate steps. I tried to do this in one step, but it was too complicated.

Now, #126064 created conflicts with #122945. I spent a day for this, and see a light at the end of tunnel, but the simplest way to resolve conflict is to revert #126064. Then merge #122945, then continue the initial plan. This will take a time.

Alternatively, I can fuse all these steps in #122945, but the result will be larger and very dirty, because I would need to use dirty tricks like using globals to pass values of local variables between function calls in three or four different modules.

erlend-aasland · 2024-11-06T08:41:14Z

Reverting #126064 will also mean reverting #126235. Are there any others that would need reverting, @skirpichev?

skirpichev · 2024-11-06T08:53:35Z

Reverting #126064 will also mean reverting #126235.

Not necessary. Reverting #126064 will just introduce some performance regression for converted functions. But as @serhiy-storchaka planned to address this issue In The Right Way - this will be eventually fixed.

Are there any others that would need reverting

None, as far as I know.

erlend-aasland · 2024-11-06T09:09:23Z

Sounds good. Serhiy, please go ahead.

skirpichev · 2024-11-06T09:24:09Z

(Given the size (few lines) of #126064, I don't see big problem to resolve merge conflicts. I'll try to do this. Serhiy, feel free to ignore these efforts.)

erlend-aasland · 2024-11-06T09:27:31Z

(Given the size (few lines) of #126064, I don't see big problem to resolve merge conflicts. I'll try to do this. Serhiy, feel free to ignore these efforts.)

IMO, this would be the best option; if we can avoid the revert churn that would be great.

skirpichev · 2024-11-06T09:31:11Z

So, if this is not urgent, give me a day.

skirpichev · 2024-11-08T06:24:00Z

I think, this is fixed by #122945 and #126560.

erlend-aasland · 2024-11-08T11:38:38Z

Thanks, @colorfulappl, for the proposal and initial work; thanks Serhiy and Sergey for the PRs 🍰 👏 🥳

…arargs (python#126064) Avoid temporary tuple creation when all arguments either positional-only or vararg. Objects/setobject.c and Modules/gcmodule.c adapted. This fixes slight performance regression for set methods, introduced by pythongh-115112.

colorfulappl mannequin added 3.11 only security fixes topic-argument-clinic performance Performance or resource usage labels Dec 31, 2021

ezio-melotti transferred this issue from another repository Apr 10, 2022

iritkatriel added 3.12 bugs and security fixes and removed 3.11 only security fixes labels Sep 7, 2022

bedevere-bot mentioned this issue Feb 27, 2023

gh-90370: Avoid temporary varargs tuple creation in argument passing #30312

Closed

erlend-aasland mentioned this issue Feb 27, 2023

gh-90350: Optimize builtin functions min() and max() #30286

Merged

skirpichev self-assigned this Oct 26, 2024

skirpichev added 3.14 new features, bugs and security fixes and removed 3.12 bugs and security fixes labels Oct 26, 2024

skirpichev mentioned this issue Oct 27, 2024

invalid signature for math.hypot #101123

Closed

bedevere-app bot mentioned this issue Oct 28, 2024

gh-90370: avoid temporary tuple creation for vararg in AC #126064

Merged

erlend-aasland linked a pull request Oct 28, 2024 that will close this issue

gh-90370: avoid temporary tuple creation for vararg in AC #126064

Merged

erlend-aasland closed this as completed in #126064 Oct 31, 2024

erlend-aasland reopened this Oct 31, 2024

skirpichev mentioned this issue Nov 7, 2024

gh-122943: Rework support of var-positional parameter in Argument Clinic #122945

Merged

skirpichev removed their assignment Nov 8, 2024

skirpichev closed this as completed Nov 8, 2024

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Avoid temporary `varargs` tuple creation in argument passing #90370

Avoid temporary `varargs` tuple creation in argument passing #90370

colorfulappl mannequin commented Dec 31, 2021 •

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Avoid temporary varargs tuple creation in argument passing #90370

Avoid temporary varargs tuple creation in argument passing #90370

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Avoid temporary `varargs` tuple creation in argument passing #90370

Avoid temporary `varargs` tuple creation in argument passing #90370

colorfulappl mannequin commented Dec 31, 2021 •

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