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bpo-45697: Use PyObject_TypeCheck in type_call and binary_op1 #29392

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Merged
serhiy-storchaka merged 2 commits into from
Nov 4, 2021
Merged

bpo-45697: Use PyObject_TypeCheck in type_call and binary_op1 #29392

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5105aef
bpo-45967: Use PyObject_TypeCheck in type_call and binary_op1
itamaro Nov 3, 2021
2362bf6
Revert change in binary_op1
itamaro Nov 3, 2021
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2 changes: 1 addition & 1 deletion Objects/typeobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1121,7 +1121,7 @@ type_call(PyTypeObject *type, PyObject *args, PyObject *kwds)

/* If the returned object is not an instance of type,
it won't be initialized. */
if (!PyType_IsSubtype(Py_TYPE(obj), type))
if (!PyObject_TypeCheck(obj, type))
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@serhiy-storchaka serhiy-storchaka Nov 3, 2021

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Creating a new type is relatively slow. I do not think that the effect of this nanooptimization is measureable.

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@itamaro itamaro Nov 3, 2021

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note that this code path is not for creating new types (which is slow as you say), but for creating new instances (which is quite fast).

I ran some synthetic benchmarks with this change and without it (on an opt build with PGO and LTO), and the gain is measurable:

build from main (commit acc89db which is the base commit for this PR):

>for _ in {1..10}; do ./main-opt/python -m timeit -n 10000 -s 'class Spam: pass' -- 'ten_k_spams = [Spam() for _ in range(10000)]'; done
10000 loops, best of 5: 896 usec per loop
10000 loops, best of 5: 887 usec per loop
10000 loops, best of 5: 857 usec per loop
10000 loops, best of 5: 838 usec per loop
10000 loops, best of 5: 847 usec per loop
10000 loops, best of 5: 863 usec per loop
10000 loops, best of 5: 845 usec per loop
10000 loops, best of 5: 902 usec per loop
10000 loops, best of 5: 890 usec per loop
10000 loops, best of 5: 875 usec per loop

build with this change applied (commit 2362bf6):

>for _ in {1..10}; do ./test-opt/python -m timeit -n 10000 -s 'class Spam: pass' -- 'ten_k_spams = [Spam() for _ in range(10000)]'; done
10000 loops, best of 5: 833 usec per loop
10000 loops, best of 5: 885 usec per loop
10000 loops, best of 5: 845 usec per loop
10000 loops, best of 5: 838 usec per loop
10000 loops, best of 5: 833 usec per loop
10000 loops, best of 5: 827 usec per loop
10000 loops, best of 5: 858 usec per loop
10000 loops, best of 5: 811 usec per loop
10000 loops, best of 5: 843 usec per loop
10000 loops, best of 5: 845 usec per loop

also worth noting that the previous approach (GH-29380) was implemented on the Instagram Server production workload in Meta/Facebook/Instagram (choose your favorite) and resulted measurable perf gain of around 0.2%

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@serhiy-storchaka serhiy-storchaka Nov 4, 2021

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Good point. Thank you for correcting me. Yes, for creating instances it makes more sense.

return obj;

type = Py_TYPE(obj);
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