[issue39117] Performance regression for making bound methods

[STINNER Victor]

STINNER Victor  added the comment:

By the way, in sorted(data, key=str.upper): str.upper is an unbound method, no?

$ ./python
Python 3.9.0a6+ (heads/master:d9a43e20fa, Apr 28 2020, 23:50:37) 
>>> type(str.upper)


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[issue39117] Performance regression for making bound methods

[STINNER Victor]

STINNER Victor  added the comment:

I compared sorted(data, key=str.upper) performance between before the removal 
of the free list (parent of commit 3e54b575313c64f541e98216ed079fafed01ff5d) 
and the current master branch, I get:

Mean +- std dev: [master] 167 us +- 4 us -> [cache] 179 us +- 7 us: 1.07x 
slower (+7%)

I cannot reproduce the "70% slowdown".

Raymond: How did you compile Python? What is your OS? How did you run your 
benchmark?

---

It's a quick & dirty benchmark run. I didn't use LTO+PGO and I didn't isolate 
my CPU. Maybe the difference of 12 ns is just caused by the noise of my coarse 
benchmark procedure.

I used commands:

# master
git checkout master
git clean -fdx
./configure && make && ./python -m venv env && env/bin/python -m pip install 
pyperf
env/bin/python -m pyperf timeit -s 'import random; data = [f"x{i}" for i in 
range(1000)]; random.shuffle(data)' 'sorted(data, key=str.upper)' -o 
../master.json

# before removal of the free list
git checkout 3e54b575313c64f541e98216ed079fafed01ff5d^
git clean -fdx
./configure && make && ./python -m venv env && env/bin/python -m pip install 
pyperf
env/bin/python -m pyperf timeit -s 'import random; data = [f"x{i}" for i in 
range(1000)]; random.shuffle(data)' 'sorted(data, key=str.upper)' -o 
../master.json

That's a Fedora 31 using GCC -O3 (GCC 9.3.1).

--

The commit before the removal of the free list is:

commit 76b645124b3aaa34bc664eece43707c01ef1b382 (HEAD)
Date:   Fri Jul 26 03:30:33 2019 +0200

Well, maybe I did a mistake.

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[issue39117] Performance regression for making bound methods

[STINNER Victor]

STINNER Victor  added the comment:

>  read_boundmethod  27.7 ns47.1 ns

Extract of Tools/scripts/var_access_benchmark.py:

def read_boundmethod(trials=trials, a=A()):
for t in trials:
a.m;a.m;a.m;a.m;a.m
a.m;a.m;a.m;a.m;a.m
a.m;a.m;a.m;a.m;a.m
a.m;a.m;a.m;a.m;a.m
a.m;a.m;a.m;a.m;a.m

Which kind of code pattern is impacted by this performance regression, apart 
this micro-benchmark? Do you notice a significant slowdown in pyperformance?

When pyperformance was run before the change was merged, there was no 
significant difference:
https://bugs.python.org/issue37340#msg348425

In bpo-37340, you wrote that sorted(data, key=str.upper) is 70% slower. Would 
you mind to provide the benchmark?

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nosy: +vstinner

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[issue39117] Performance regression for making bound methods

[Raymond Hettinger]

Raymond Hettinger  added the comment:

This performance regression in still present in 3.9.0a6

Results from Tools/scripts/var_access_benchmark.py:

 Python 3.8.2   Python 3.9.0a6
    --
  read_boundmethod  27.7 ns 47.1 ns




> Is this regression is large enough to revive the free_list 
> for bound methods?

Yes!

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[issue39117] Performance regression for making bound methods

[Pablo Galindo Salgado]

Change by Pablo Galindo Salgado :


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[issue39117] Performance regression for making bound methods

[Inada Naoki]

Inada Naoki  added the comment:

Is this regression is large enough to revive the free_list for bound methods?

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[issue39117] Performance regression for making bound methods

[Serhiy Storchaka]

Change by Serhiy Storchaka :


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nosy: +inada.naoki, serhiy.storchaka

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[issue39117] Performance regression for making bound methods

[Benjamin Peterson]

Benjamin Peterson  added the comment:

Probably #37340

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[issue39117] Performance regression for making bound methods

[Raymond Hettinger]

New submission from Raymond Hettinger :

$ python3.9 -m timeit -r 11 -s 'class A: pass' -s 'A.m = lambda s: None' -s 'a 
= A()' 'a.m; a.m; a.m; a.m; a.m'
100 loops, best of 11: 230 nsec per loop

$ python3.8 -m timeit -r 11 -s 'class A: pass' -s 'A.m = lambda s: None' -s 'a 
= A()' 'a.m; a.m; a.m; a.m; a.m'
200 loops, best of 11: 149 nsec per loop

$ python3.7 -m timeit -r 11 -s 'class A: pass' -s 'A.m = lambda s: None' -s 'a 
= A()' 'a.m; a.m; a.m; a.m; a.m'
200 loops, best of 11: 159 nsec per loop

$ python3.6 -m timeit -r 11 -s 'class A: pass' -s 'A.m = lambda s: None' -s 'a 
= A()' 'a.m; a.m; a.m; a.m; a.m'
1000 loops, best of 11: 0.159 usec per loop

Timings made using the recent released python.org macOS 64-bit builds.

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components: Interpreter Core
messages: 358781
nosy: rhettinger
priority: normal
severity: normal
status: open
title: Performance regression for making bound methods
type: performance
versions: Python 3.9

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