[Python-Dev] Possible performance regression

[Eric Snow]

On Sun, Feb 24, 2019 at 10:04 PM Eric Snow <ericsnowcurrently at gmail.com> wrote:
> I'll take a look tonight.

I made 2 successive runs of the script (on my laptop) for a commit
from early Saturday, and 2 runs from a commit this afternoon (close to
master).  The output is below, with the earlier commit first.  That
one is a little faster in places and a little slower in others.
However, I also saw quite a bit of variability in the results for the
same commit.  So I'm not sure what to make of it.

I'll look into it in more depth tomorrow.  FWIW, I have a few commits
in the range you described, so I want to make sure I didn't slow
things down for us. :)

-eric


* commit 175421b58cc97a2555e474f479f30a6c5d2250b0 (HEAD)
| Author: Pablo Galindo <Pablogsal at gmail.com>
| Date:   Sat Feb 23 03:02:06 2019 +0000
|
|     bpo-36016: Add generation option to gc.getobjects() (GH-11909)

$ ./python Tools/scripts/var_access_benchmark.py
Variable and attribute read access:
  18.1 ns       read_local
  19.4 ns       read_nonlocal
  48.3 ns       read_global
  52.4 ns       read_builtin
  55.7 ns       read_classvar_from_class
  56.1 ns       read_classvar_from_instance
  78.6 ns       read_instancevar
  67.6 ns       read_instancevar_slots
  65.9 ns       read_namedtuple
 106.1 ns       read_boundmethod

Variable and attribute write access:
  25.1 ns       write_local
  26.9 ns       write_nonlocal
^[[A
  78.0 ns       write_global
 154.1 ns       write_classvar
 132.0 ns       write_instancevar
  88.2 ns       write_instancevar_slots

Data structure read access:
  69.6 ns       read_list
  69.0 ns       read_deque
  68.4 ns       read_dict

Data structure write access:
  73.2 ns       write_list
  79.0 ns       write_deque
 103.5 ns       write_dict

Stack (or queue) operations:
 348.3 ns       list_append_pop
 169.0 ns       deque_append_pop
 170.8 ns       deque_append_popleft

Timing loop overhead:
   1.3 ns       loop_overhead
$ ./python Tools/scripts/var_access_benchmark.py
Variable and attribute read access:
  17.7 ns       read_local
  19.2 ns       read_nonlocal
  39.9 ns       read_global
  50.3 ns       read_builtin
  54.4 ns       read_classvar_from_class
  55.8 ns       read_classvar_from_instance
  80.3 ns       read_instancevar
  70.7 ns       read_instancevar_slots
  66.1 ns       read_namedtuple
 108.9 ns       read_boundmethod

Variable and attribute write access:
  25.1 ns       write_local
  25.6 ns       write_nonlocal
  70.0 ns       write_global
 151.5 ns       write_classvar
 133.9 ns       write_instancevar
  90.7 ns       write_instancevar_slots

Data structure read access:
 140.7 ns       read_list
  89.6 ns       read_deque
  86.6 ns       read_dict

Data structure write access:
  97.9 ns       write_list
 100.5 ns       write_deque
 120.0 ns       write_dict

Stack (or queue) operations:
 375.9 ns       list_append_pop
 179.3 ns       deque_append_pop
 179.4 ns       deque_append_popleft

Timing loop overhead:
   1.5 ns       loop_overhead

* commit 3b0abb019662e42070f1d6f7e74440afb1808f03 (HEAD)
| Author: Giampaolo Rodola <g.rodola at gmail.com>
| Date:   Sun Feb 24 15:46:40 2019 -0800
|
|     bpo-33671: allow setting shutil.copyfile() bufsize globally (GH-12016)

$ ./python Tools/scripts/var_access_benchmark.py
Variable and attribute read access:
  20.2 ns       read_local
  20.0 ns       read_nonlocal
  41.9 ns       read_global
  52.9 ns       read_builtin
  56.3 ns       read_classvar_from_class
  56.9 ns       read_classvar_from_instance
  80.2 ns       read_instancevar
  70.6 ns       read_instancevar_slots
  69.5 ns       read_namedtuple
 114.5 ns       read_boundmethod

Variable and attribute write access:
  23.4 ns       write_local
  25.0 ns       write_nonlocal
  74.5 ns       write_global
 152.0 ns       write_classvar
 131.7 ns       write_instancevar
  90.1 ns       write_instancevar_slots

Data structure read access:
  69.9 ns       read_list
  73.4 ns       read_deque
  77.8 ns       read_dict

Data structure write access:
  83.3 ns       write_list
  94.9 ns       write_deque
 120.6 ns       write_dict

Stack (or queue) operations:
 383.4 ns       list_append_pop
 187.1 ns       deque_append_pop
 182.2 ns       deque_append_popleft

Timing loop overhead:
   1.4 ns       loop_overhead
$ ./python Tools/scripts/var_access_benchmark.py
Variable and attribute read access:
  19.1 ns       read_local
  20.9 ns       read_nonlocal
  43.8 ns       read_global
  57.8 ns       read_builtin
  58.4 ns       read_classvar_from_class
  61.3 ns       read_classvar_from_instance
  84.7 ns       read_instancevar
  72.9 ns       read_instancevar_slots
  69.7 ns       read_namedtuple
 109.9 ns       read_boundmethod

Variable and attribute write access:
  23.1 ns       write_local
  23.7 ns       write_nonlocal
  72.8 ns       write_global
 149.9 ns       write_classvar
 133.3 ns       write_instancevar
  89.4 ns       write_instancevar_slots

Data structure read access:
  69.0 ns       read_list
  69.6 ns       read_deque
  69.1 ns       read_dict

Data structure write access:
  74.5 ns       write_list
  80.9 ns       write_deque
 105.4 ns       write_dict

Stack (or queue) operations:
 338.2 ns       list_append_pop
 165.6 ns       deque_append_pop
 164.7 ns       deque_append_popleft

Timing loop overhead:
   1.3 ns       loop_overhead