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gh-131586: Avoid refcount contention in some "special" calls (#131588)

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In the free threaded build, the `_PyObject_LookupSpecial()` call can lead to
reference count contention on the returned function object becuase it
doesn't use stackrefs. Refactor some of the callers to use
`_PyObject_MaybeCallSpecialNoArgs`, which uses stackrefs internally.

This fixes the scaling bottleneck in the "lookup_special" microbenchmark
in `ftscalingbench.py`. However, the are still some uses of
`_PyObject_LookupSpecial()` that need to be addressed in future PRs.
This commit is contained in:
Sam Gross 2025-03-26 14:38:47 -04:00 • committed by GitHub
parent 3d4ac1a2c2
commit 67fbfb42bd
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GPG key ID: B5690EEEBB952194
16 changed files with 450 additions and 374 deletions
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94
Modules/mathmodule.c
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@ -78,19 +78,6 @@ module math
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=76bc7002685dd942]*/
typedef struct {
PyObject *str___ceil__;
PyObject *str___floor__;
PyObject *str___trunc__;
} math_module_state;
static inline math_module_state*
get_math_module_state(PyObject *module)
{
void *state = _PyModule_GetState(module);
assert(state != NULL);
return (math_module_state *)state;
}
/*
Double and triple length extended precision algorithms from:
@ -1140,18 +1127,17 @@ math_ceil(PyObject *module, PyObject *number)
x = PyFloat_AS_DOUBLE(number);
}
else {
math_module_state *state = get_math_module_state(module);
PyObject *method = _PyObject_LookupSpecial(number, state->str___ceil__);
if (method != NULL) {
PyObject *result = _PyObject_CallNoArgs(method);
Py_DECREF(method);
PyObject *result = _PyObject_MaybeCallSpecialNoArgs(number, &_Py_ID(__ceil__));
if (result != NULL) {
return result;
}
if (PyErr_Occurred())
else if (PyErr_Occurred()) {
return NULL;
}
x = PyFloat_AsDouble(number);
if (x == -1.0 && PyErr_Occurred())
if (x == -1.0 && PyErr_Occurred()) {
return NULL;
}
}
return PyLong_FromDouble(ceil(x));
}
@ -1209,18 +1195,17 @@ math_floor(PyObject *module, PyObject *number)
x = PyFloat_AS_DOUBLE(number);
}
else {
math_module_state *state = get_math_module_state(module);
PyObject *method = _PyObject_LookupSpecial(number, state->str___floor__);
if (method != NULL) {
PyObject *result = _PyObject_CallNoArgs(method);
Py_DECREF(method);
PyObject *result = _PyObject_MaybeCallSpecialNoArgs(number, &_Py_ID(__floor__));
if (result != NULL) {
return result;
}
if (PyErr_Occurred())
else if (PyErr_Occurred()) {
return NULL;
}
x = PyFloat_AsDouble(number);
if (x == -1.0 && PyErr_Occurred())
if (x == -1.0 && PyErr_Occurred()) {
return NULL;
}
}
return PyLong_FromDouble(floor(x));
}
@ -2074,24 +2059,20 @@ static PyObject *
math_trunc(PyObject *module, PyObject *x)
/*[clinic end generated code: output=34b9697b707e1031 input=2168b34e0a09134d]*/
{
PyObject *trunc, *result;
if (PyFloat_CheckExact(x)) {
return PyFloat_Type.tp_as_number->nb_int(x);
}
math_module_state *state = get_math_module_state(module);
trunc = _PyObject_LookupSpecial(x, state->str___trunc__);
if (trunc == NULL) {
if (!PyErr_Occurred())
PyErr_Format(PyExc_TypeError,
"type %.100s doesn't define __trunc__ method",
Py_TYPE(x)->tp_name);
return NULL;
PyObject *result = _PyObject_MaybeCallSpecialNoArgs(x, &_Py_ID(__trunc__));
if (result != NULL) {
return result;
}
result = _PyObject_CallNoArgs(trunc);
Py_DECREF(trunc);
return result;
else if (!PyErr_Occurred()) {
PyErr_Format(PyExc_TypeError,
"type %.100s doesn't define __trunc__ method",
Py_TYPE(x)->tp_name);
}
return NULL;
}
@ -4084,19 +4065,6 @@ static int
math_exec(PyObject *module)
{
math_module_state *state = get_math_module_state(module);
state->str___ceil__ = PyUnicode_InternFromString("__ceil__");
if (state->str___ceil__ == NULL) {
return -1;
}
state->str___floor__ = PyUnicode_InternFromString("__floor__");
if (state->str___floor__ == NULL) {
return -1;
}
state->str___trunc__ = PyUnicode_InternFromString("__trunc__");
if (state->str___trunc__ == NULL) {
return -1;
}
if (PyModule_Add(module, "pi", PyFloat_FromDouble(Py_MATH_PI)) < 0) {
return -1;
}
@ -4116,22 +4084,6 @@ math_exec(PyObject *module)
return 0;
}
static int
math_clear(PyObject *module)
{
math_module_state *state = get_math_module_state(module);
Py_CLEAR(state->str___ceil__);
Py_CLEAR(state->str___floor__);
Py_CLEAR(state->str___trunc__);
return 0;
}
static void
math_free(void *module)
{
math_clear((PyObject *)module);
}
static PyMethodDef math_methods[] = {
{"acos", math_acos, METH_O, math_acos_doc},
{"acosh", math_acosh, METH_O, math_acosh_doc},
@ -4208,11 +4160,9 @@ static struct PyModuleDef mathmodule = {
PyModuleDef_HEAD_INIT,
.m_name = "math",
.m_doc = module_doc,
.m_size = sizeof(math_module_state),
.m_size = 0,
.m_methods = math_methods,
.m_slots = math_slots,
.m_clear = math_clear,
.m_free = math_free,
};
PyMODINIT_FUNC