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bpo-35884: Add variable access benchmarking script (GH-11725)
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‎Doc/whatsnew/3.8.rst

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@@ -551,3 +551,11 @@ CPython bytecode changes
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* Added new opcode :opcode:`END_ASYNC_FOR` for handling exceptions raised
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when awaiting a next item in an :keyword:`async for` loop.
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(Contributed by Serhiy Storchaka in :issue:`33041`.)
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Demos and Tools
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---------------
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* Added a benchmark script for timing various ways to access variables:
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``Tools/scripts/var_access_benchmark.py``.
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(Contributed by Raymond Hettinger in :issue:`35884`.)

‎Misc/NEWS.d/next/Tools-Demos/2019-02-01-12-22-37.bpo-35884.hJkMRD.rst

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Add a benchmark script for timing various ways to access variables:
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``Tools/scripts/var_access_benchmark.py``.

‎Tools/scripts/var_access_benchmark.py

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'Show relative speeds of local, nonlocal, global, and built-in access.'
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# Please leave this code so that it runs under older versions of
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# Python 3 (no f-strings). That will allow benchmarking for
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# cross-version comparisons. To run the benchmark on Python 2,
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# comment-out the nonlocal reads and writes.
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from collections import deque, namedtuple
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trials = [None] * 500
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steps_per_trial = 25
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class A(object):
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def m(self):
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pass
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class B(object):
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__slots__ = 'x'
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def __init__(self, x):
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self.x = x
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class C(object):
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def __init__(self, x):
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self.x = x
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def read_local(trials=trials):
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v_local = 1
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for t in trials:
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v_local; v_local; v_local; v_local; v_local
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v_local; v_local; v_local; v_local; v_local
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v_local; v_local; v_local; v_local; v_local
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v_local; v_local; v_local; v_local; v_local
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v_local; v_local; v_local; v_local; v_local
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def make_nonlocal_reader():
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v_nonlocal = 1
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def inner(trials=trials):
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for t in trials:
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v_nonlocal; v_nonlocal; v_nonlocal; v_nonlocal; v_nonlocal
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v_nonlocal; v_nonlocal; v_nonlocal; v_nonlocal; v_nonlocal
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v_nonlocal; v_nonlocal; v_nonlocal; v_nonlocal; v_nonlocal
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v_nonlocal; v_nonlocal; v_nonlocal; v_nonlocal; v_nonlocal
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v_nonlocal; v_nonlocal; v_nonlocal; v_nonlocal; v_nonlocal
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inner.__name__ = 'read_nonlocal'
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return inner
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read_nonlocal = make_nonlocal_reader()
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v_global = 1
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def read_global(trials=trials):
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for t in trials:
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v_global; v_global; v_global; v_global; v_global
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v_global; v_global; v_global; v_global; v_global
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v_global; v_global; v_global; v_global; v_global
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v_global; v_global; v_global; v_global; v_global
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v_global; v_global; v_global; v_global; v_global
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def read_builtin(trials=trials):
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for t in trials:
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oct; oct; oct; oct; oct
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oct; oct; oct; oct; oct
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oct; oct; oct; oct; oct
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oct; oct; oct; oct; oct
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oct; oct; oct; oct; oct
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def read_classvar_from_class(trials=trials, A=A):
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A.x = 1
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for t in trials:
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A.x; A.x; A.x; A.x; A.x
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A.x; A.x; A.x; A.x; A.x
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A.x; A.x; A.x; A.x; A.x
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A.x; A.x; A.x; A.x; A.x
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A.x; A.x; A.x; A.x; A.x
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def read_classvar_from_instance(trials=trials, A=A):
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A.x = 1
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a = A()
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for t in trials:
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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def read_instancevar(trials=trials, a=C(1)):
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for t in trials:
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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def read_instancevar_slots(trials=trials, a=B(1)):
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for t in trials:
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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def read_namedtuple(trials=trials, D=namedtuple('D', ['x'])):
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a = D(1)
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for t in trials:
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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a.x; a.x; a.x; a.x; a.x
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def read_boundmethod(trials=trials, a=A()):
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for t in trials:
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a.m; a.m; a.m; a.m; a.m
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a.m; a.m; a.m; a.m; a.m
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a.m; a.m; a.m; a.m; a.m
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a.m; a.m; a.m; a.m; a.m
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a.m; a.m; a.m; a.m; a.m
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def write_local(trials=trials):
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v_local = 1
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for t in trials:
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v_local = 1; v_local = 1; v_local = 1; v_local = 1; v_local = 1
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v_local = 1; v_local = 1; v_local = 1; v_local = 1; v_local = 1
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v_local = 1; v_local = 1; v_local = 1; v_local = 1; v_local = 1
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v_local = 1; v_local = 1; v_local = 1; v_local = 1; v_local = 1
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v_local = 1; v_local = 1; v_local = 1; v_local = 1; v_local = 1
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def make_nonlocal_writer():
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v_nonlocal = 1
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def inner(trials=trials):
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nonlocal v_nonlocal
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for t in trials:
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v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1
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v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1
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v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1
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v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1
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v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1; v_nonlocal = 1
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inner.__name__ = 'write_nonlocal'
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return inner
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write_nonlocal = make_nonlocal_writer()
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def write_global(trials=trials):
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global v_global
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for t in trials:
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v_global = 1; v_global = 1; v_global = 1; v_global = 1; v_global = 1
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v_global = 1; v_global = 1; v_global = 1; v_global = 1; v_global = 1
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v_global = 1; v_global = 1; v_global = 1; v_global = 1; v_global = 1
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v_global = 1; v_global = 1; v_global = 1; v_global = 1; v_global = 1
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v_global = 1; v_global = 1; v_global = 1; v_global = 1; v_global = 1
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def write_classvar(trials=trials, A=A):
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for t in trials:
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A.x = 1; A.x = 1; A.x = 1; A.x = 1; A.x = 1
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A.x = 1; A.x = 1; A.x = 1; A.x = 1; A.x = 1
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A.x = 1; A.x = 1; A.x = 1; A.x = 1; A.x = 1
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A.x = 1; A.x = 1; A.x = 1; A.x = 1; A.x = 1
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A.x = 1; A.x = 1; A.x = 1; A.x = 1; A.x = 1
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def write_instancevar(trials=trials, a=C(1)):
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for t in trials:
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a.x = 1; a.x = 1; a.x = 1; a.x = 1; a.x = 1
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a.x = 1; a.x = 1; a.x = 1; a.x = 1; a.x = 1
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a.x = 1; a.x = 1; a.x = 1; a.x = 1; a.x = 1
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a.x = 1; a.x = 1; a.x = 1; a.x = 1; a.x = 1
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a.x = 1; a.x = 1; a.x = 1; a.x = 1; a.x = 1
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def write_instancevar_slots(trials=trials, a=B(1)):
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for t in trials:
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a.x = 1; a.x = 1; a.x = 1; a.x = 1; a.x = 1
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a.x = 1; a.x = 1; a.x = 1; a.x = 1; a.x = 1
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a.x = 1; a.x = 1; a.x = 1; a.x = 1; a.x = 1
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a.x = 1; a.x = 1; a.x = 1; a.x = 1; a.x = 1
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a.x = 1; a.x = 1; a.x = 1; a.x = 1; a.x = 1
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def read_list(trials=trials, a=[1]):
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for t in trials:
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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def read_deque(trials=trials, a=deque([1])):
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for t in trials:
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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def read_dict(trials=trials, a={0: 1}):
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for t in trials:
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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a[0]; a[0]; a[0]; a[0]; a[0]
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def list_append_pop(trials=trials, a=[1]):
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ap, pop = a.append, a.pop
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for t in trials:
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ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop();
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ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop();
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ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop();
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ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop();
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ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop();
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def deque_append_pop(trials=trials, a=deque([1])):
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ap, pop = a.append, a.pop
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for t in trials:
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ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop();
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ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop();
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ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop();
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ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop();
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ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop(); ap(1); pop();
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def write_list(trials=trials, a=[1]):
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for t in trials:
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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def write_deque(trials=trials, a=deque([1])):
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for t in trials:
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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def write_dict(trials=trials, a={0: 1}):
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for t in trials:
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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a[0]=1; a[0]=1; a[0]=1; a[0]=1; a[0]=1
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def loop_overhead(trials=trials):
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for t in trials:
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pass
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if __name__=='__main__':
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from timeit import Timer
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for f in [
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'Variable and attribute read access:',
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read_local, read_nonlocal, read_global, read_builtin,
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read_classvar_from_class, read_classvar_from_instance,
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read_instancevar, read_instancevar_slots,
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read_namedtuple, read_boundmethod,
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'\nVariable and attribute write access:',
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write_local, write_nonlocal, write_global,
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write_classvar, write_instancevar, write_instancevar_slots,
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'\nData structure read access:',
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read_list, read_deque, read_dict,
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'\nData structure write access:',
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write_list, write_deque, write_dict,
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'\nStack (or queue) operations:',
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list_append_pop, deque_append_pop,
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'\nTiming loop overhead:',
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loop_overhead]:
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if isinstance(f, str):
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print(f)
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continue
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timing = min(Timer(f).repeat(7, 1000))
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timing *= 1000000 / (len(trials) * steps_per_trial)
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print(u'{:6.1f} \N{greek small letter mu}s\t{}'.format(timing, f.__name__))

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