Speed hack for function calls with named parameters

[pitrou]

BPO	1819
Nosy	@malemburg, @gvanrossum, @birkenfeld, @rhettinger, @facundobatista, @pitrou, @tiran
Files	namedparam.patch namedparam.patch namedparam2.patch namedparam3.patch: Faster, cleaner with PySequence_Fast_ITEMS pybench.patch

^{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: ```python assignee = 'https://github.com/birkenfeld' closed_at = created_at = labels = ['interpreter-core', 'type-feature'] title = 'Speed hack for function calls with named parameters' updated_at = user = 'https://github.com/pitrou' ``` bugs.python.org fields: ```python activity = actor = 'pitrou' assignee = 'georg.brandl' closed = True closed_date = closer = 'pitrou' components = ['Interpreter Core'] creation = creator = 'pitrou' dependencies = [] files = ['9156', '9157', '10590', '10596', '10600'] hgrepos = [] issue_num = 1819 keywords = ['patch'] message_count = 12.0 messages = ['59878', '59879', '59880', '59882', '61556', '68007', '68025', '68026', '68040', '68070', '68092', '70283'] nosy_count = 7.0 nosy_names = ['lemburg', 'gvanrossum', 'georg.brandl', 'rhettinger', 'facundobatista', 'pitrou', 'christian.heimes'] pr_nums = [] priority = 'normal' resolution = 'fixed' stage = None status = 'closed' superseder = None type = 'enhancement' url = 'https://bugs.python.org/issue1819' versions = ['Python 2.6'] ```

[pitrou]

This is a patch for SVN trunk which substantially speeds up function calls with named parameters. It does so by taking into account that parameter names should be interned, so before doing full compares we do a first quick loop to compare pointers.

On a microbenchmark the speedup is quite distinctive:

# With patch $ ./python -m timeit -s "def f(a,b,c,d,e): pass" "f(1,2,3,4,e=5)" 1000000 loops, best of 3: 0.515 usec per loop $ ./python -m timeit -s "def f(a,b,c,d,e): pass" "f(a=1,b=2,c=3,d=4,e=5)" 1000000 loops, best of 3: 0.652 usec per loop

# Without patch $ ./python-orig -m timeit -s "def f(a,b,c,d,e): pass" "f(1,2,3,4,e=5)" 1000000 loops, best of 3: 0.664 usec per loop $ ./python-orig -m timeit -s "def f(a,b,c,d,e): pass" "f(a=1,b=2,c=3,d=4,e=5)" 1000000 loops, best of 3: 1.07 usec per loop

[tiran]

Nice! Is this somehow related to bpo-1479611?

The formatting of the code looks kinda strange. Have you mixed tabs and spaces?

[pitrou]

Sorry, my editor indents with spaces by default. Attaching a fixed patch with tabs.

No, it is independent from bpo-1479611 (and much simpler).

[pitrou]

Another quick test:

# With patch $ ./python -m timeit -s "d=dict(a=1,b=2,c=3,d=4,e=5);f = lambda a,b,c,d,e:0" "f(d)" 1000000 loops, best of 3: 0.727 usec per loop $ ./python -m timeit -s "d=dict(b=2,c=3,d=4,e=5);f = lambda a,b,c,d,e:0" "f(a=1,d)" 1000000 loops, best of 3: 1.16 usec per loop $ ./python -m timeit -s "d=dict(b=2,c=3,d=4,e=5); f=lambda **kw:0" "f(**d)" 1000000 loops, best of 3: 0.917 usec per loop

# Without patch $ ./python-orig -m timeit -s "d=dict(a=1,b=2,c=3,d=4,e=5);f = lambda a,b,c,d,e:0" "f(d)" 1000000 loops, best of 3: 1.24 usec per loop $ ./python-orig -m timeit -s "d=dict(b=2,c=3,d=4,e=5);f = lambda a,b,c,d,e:0" "f(a=1,d)" 1000000 loops, best of 3: 1.62 usec per loop $ ./python-orig -m timeit -s "d=dict(b=2,c=3,d=4,e=5); f=lambda **kw:0" "f(**d)" 1000000 loops, best of 3: 0.904 usec per loop

[gvanrossum]

Nice idea, but why set the priority to high? I have no immediate time to review this and probably won't for a while.

[pitrou]

Here is a new patch against SVN trunk. Nothing changed, except that I updated pybench to test keyword arguments as well.

[malemburg]

On 2008-06-11 20:38, Antoine Pitrou wrote:

Antoine Pitrou \pitrou@free.fr\ added the comment:

Here is a new patch against SVN trunk. Nothing changed, except that I updated pybench to test keyword arguments as well.

Added file: http://bugs.python.org/file10590/namedparam2.patch

When changing parameters or other aspects of pybench tests, you *have* to update the version number of the test as well. Otherwise, pybench would compare apples with oranges.

Thanks, -- Marc-Andre Lemburg eGenix.com

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[malemburg]

On 2008-06-11 23:27, M.-A. Lemburg wrote:

On 2008-06-11 20:38, Antoine Pitrou wrote: > Antoine Pitrou \pitrou@free.fr\ added the comment: > > Here is a new patch against SVN trunk. Nothing changed, except that I > updated pybench to test keyword arguments as well. > > Added file: http://bugs.python.org/file10590/namedparam2.patch

When changing parameters or other aspects of pybench tests, you *have* to update the version number of the test as well. Otherwise, pybench would compare apples with oranges.

BTW: It would probably be better to add a completely new test PythonNamedParameterCalls or something along those lines instead of changing an existing test.

[rhettinger]

Attaching a version that's a little faster and cleaner with PySequence_Fast_ITEMS.

[pitrou]

And here is a patch adding a new test in pybench as suggested by Marc-Andre Lemburg.

[rhettinger]

Georg, do you want to go ahead and apply this.

[pitrou]

Committed in r65240 (new pybench test) and r65241 (speedup patch).