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gh-131586: Avoid refcount contention in context managers (gh-131851)

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This avoid reference count contention in the free threading build
when calling special methods like `__enter__` and `__exit__`.
This commit is contained in:
Sam Gross 2025-04-21 15:54:25 -04:00 • committed by GitHub
parent 8dfa840773
commit da53660f35
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GPG key ID: B5690EEEBB952194
11 changed files with 247 additions and 207 deletions
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31
Python/bytecodes.c
View file

@ -3417,28 +3417,33 @@ dummy_func(
_FOR_ITER_GEN_FRAME +
_PUSH_FRAME;
inst(LOAD_SPECIAL, (owner -- attr, self_or_null)) {
assert(oparg <= SPECIAL_MAX);
PyObject *owner_o = PyStackRef_AsPyObjectSteal(owner);
op(_INSERT_NULL, (self -- method_and_self[2])) {
method_and_self[1] = self;
method_and_self[0] = PyStackRef_NULL;
DEAD(self);
}
op(_LOAD_SPECIAL, (method_and_self[2] -- method_and_self[2])) {
PyObject *name = _Py_SpecialMethods[oparg].name;
PyObject *self_or_null_o;
PyObject *attr_o = _PyObject_LookupSpecialMethod(owner_o, name, &self_or_null_o);
if (attr_o == NULL) {
if (!_PyErr_Occurred(tstate)) {
const char *errfmt = _PyEval_SpecialMethodCanSuggest(owner_o, oparg)
int err = _PyObject_LookupSpecialMethod(name, method_and_self);
if (err <= 0) {
if (err == 0) {
PyObject *owner = PyStackRef_AsPyObjectBorrow(method_and_self[1]);
const char *errfmt = _PyEval_SpecialMethodCanSuggest(owner, oparg)
? _Py_SpecialMethods[oparg].error_suggestion
: _Py_SpecialMethods[oparg].error;
assert(!_PyErr_Occurred(tstate));
assert(errfmt != NULL);
_PyErr_Format(tstate, PyExc_TypeError, errfmt, owner_o);
_PyErr_Format(tstate, PyExc_TypeError, errfmt, owner);
}
ERROR_IF(true, error);
ERROR_NO_POP();
}
attr = PyStackRef_FromPyObjectSteal(attr_o);
self_or_null = self_or_null_o == NULL ?
PyStackRef_NULL : PyStackRef_FromPyObjectSteal(self_or_null_o);
}
macro(LOAD_SPECIAL) =
_INSERT_NULL +
_LOAD_SPECIAL;
inst(WITH_EXCEPT_START, (exit_func, exit_self, lasti, unused, val -- exit_func, exit_self, lasti, unused, val, res)) {
/* At the top of the stack are 4 values:
- val: TOP = exc_info()

45
Python/executor_cases.c.h generated
View file

@ -4407,43 +4407,42 @@
break;
}
case _LOAD_SPECIAL: {
_PyStackRef owner;
_PyStackRef attr;
_PyStackRef self_or_null;
oparg = CURRENT_OPARG();
owner = stack_pointer[-1];
assert(oparg <= SPECIAL_MAX);
PyObject *owner_o = PyStackRef_AsPyObjectSteal(owner);
PyObject *name = _Py_SpecialMethods[oparg].name;
PyObject *self_or_null_o;
stack_pointer += -1;
case _INSERT_NULL: {
_PyStackRef self;
_PyStackRef *method_and_self;
self = stack_pointer[-1];
method_and_self = &stack_pointer[-1];
method_and_self[1] = self;
method_and_self[0] = PyStackRef_NULL;
stack_pointer += 1;
assert(WITHIN_STACK_BOUNDS());
break;
}
case _LOAD_SPECIAL: {
_PyStackRef *method_and_self;
oparg = CURRENT_OPARG();
method_and_self = &stack_pointer[-2];
PyObject *name = _Py_SpecialMethods[oparg].name;
_PyFrame_SetStackPointer(frame, stack_pointer);
PyObject *attr_o = _PyObject_LookupSpecialMethod(owner_o, name, &self_or_null_o);
int err = _PyObject_LookupSpecialMethod(name, method_and_self);
stack_pointer = _PyFrame_GetStackPointer(frame);
if (attr_o == NULL) {
if (!_PyErr_Occurred(tstate)) {
if (err <= 0) {
if (err == 0) {
PyObject *owner = PyStackRef_AsPyObjectBorrow(method_and_self[1]);
_PyFrame_SetStackPointer(frame, stack_pointer);
const char *errfmt = _PyEval_SpecialMethodCanSuggest(owner_o, oparg)
const char *errfmt = _PyEval_SpecialMethodCanSuggest(owner, oparg)
? _Py_SpecialMethods[oparg].error_suggestion
: _Py_SpecialMethods[oparg].error;
stack_pointer = _PyFrame_GetStackPointer(frame);
assert(!_PyErr_Occurred(tstate));
assert(errfmt != NULL);
_PyFrame_SetStackPointer(frame, stack_pointer);
_PyErr_Format(tstate, PyExc_TypeError, errfmt, owner_o);
_PyErr_Format(tstate, PyExc_TypeError, errfmt, owner);
stack_pointer = _PyFrame_GetStackPointer(frame);
}
JUMP_TO_ERROR();
}
attr = PyStackRef_FromPyObjectSteal(attr_o);
self_or_null = self_or_null_o == NULL ?
PyStackRef_NULL : PyStackRef_FromPyObjectSteal(self_or_null_o);
stack_pointer[0] = attr;
stack_pointer[1] = self_or_null;
stack_pointer += 2;
assert(WITHIN_STACK_BOUNDS());
break;
}

68
Python/generated_cases.c.h generated
View file

@ -9342,41 +9342,41 @@
frame->instr_ptr = next_instr;
next_instr += 1;
INSTRUCTION_STATS(LOAD_SPECIAL);
_PyStackRef owner;
_PyStackRef attr;
_PyStackRef self_or_null;
owner = stack_pointer[-1];
assert(oparg <= SPECIAL_MAX);
PyObject *owner_o = PyStackRef_AsPyObjectSteal(owner);
PyObject *name = _Py_SpecialMethods[oparg].name;
PyObject *self_or_null_o;
stack_pointer += -1;
assert(WITHIN_STACK_BOUNDS());
_PyFrame_SetStackPointer(frame, stack_pointer);
PyObject *attr_o = _PyObject_LookupSpecialMethod(owner_o, name, &self_or_null_o);
stack_pointer = _PyFrame_GetStackPointer(frame);
if (attr_o == NULL) {
if (!_PyErr_Occurred(tstate)) {
_PyFrame_SetStackPointer(frame, stack_pointer);
const char *errfmt = _PyEval_SpecialMethodCanSuggest(owner_o, oparg)
? _Py_SpecialMethods[oparg].error_suggestion
: _Py_SpecialMethods[oparg].error;
stack_pointer = _PyFrame_GetStackPointer(frame);
assert(!_PyErr_Occurred(tstate));
assert(errfmt != NULL);
_PyFrame_SetStackPointer(frame, stack_pointer);
_PyErr_Format(tstate, PyExc_TypeError, errfmt, owner_o);
stack_pointer = _PyFrame_GetStackPointer(frame);
}
JUMP_TO_LABEL(error);
_PyStackRef self;
_PyStackRef *method_and_self;
// _INSERT_NULL
{
self = stack_pointer[-1];
method_and_self = &stack_pointer[-1];
method_and_self[1] = self;
method_and_self[0] = PyStackRef_NULL;
}
// _LOAD_SPECIAL
{
method_and_self = &stack_pointer[-1];
PyObject *name = _Py_SpecialMethods[oparg].name;
stack_pointer += 1;
assert(WITHIN_STACK_BOUNDS());
_PyFrame_SetStackPointer(frame, stack_pointer);
int err = _PyObject_LookupSpecialMethod(name, method_and_self);
stack_pointer = _PyFrame_GetStackPointer(frame);
if (err <= 0) {
if (err == 0) {
PyObject *owner = PyStackRef_AsPyObjectBorrow(method_and_self[1]);
_PyFrame_SetStackPointer(frame, stack_pointer);
const char *errfmt = _PyEval_SpecialMethodCanSuggest(owner, oparg)
? _Py_SpecialMethods[oparg].error_suggestion
: _Py_SpecialMethods[oparg].error;
stack_pointer = _PyFrame_GetStackPointer(frame);
assert(!_PyErr_Occurred(tstate));
assert(errfmt != NULL);
_PyFrame_SetStackPointer(frame, stack_pointer);
_PyErr_Format(tstate, PyExc_TypeError, errfmt, owner);
stack_pointer = _PyFrame_GetStackPointer(frame);
}
JUMP_TO_LABEL(error);
}
}
attr = PyStackRef_FromPyObjectSteal(attr_o);
self_or_null = self_or_null_o == NULL ?
PyStackRef_NULL : PyStackRef_FromPyObjectSteal(self_or_null_o);
stack_pointer[0] = attr;
stack_pointer[1] = self_or_null;
stack_pointer += 2;
assert(WITHIN_STACK_BOUNDS());
DISPATCH();
}

11
Python/optimizer_bytecodes.c
View file

@ -897,9 +897,14 @@ dummy_func(void) {
}
}
op(_LOAD_SPECIAL, (owner -- attr, self_or_null)) {
attr = sym_new_not_null(ctx);
self_or_null = sym_new_unknown(ctx);
op(_INSERT_NULL, (self -- method_and_self[2])) {
method_and_self[0] = sym_new_null(ctx);
method_and_self[1] = self;
}
op(_LOAD_SPECIAL, (method_and_self[2] -- method_and_self[2])) {
method_and_self[0] = sym_new_not_null(ctx);
method_and_self[1] = sym_new_unknown(ctx);
}
op(_JUMP_TO_TOP, (--)) {

22
Python/optimizer_cases.c.h generated
View file

@ -1553,18 +1553,26 @@
break;
}
case _LOAD_SPECIAL: {
JitOptSymbol *attr;
JitOptSymbol *self_or_null;
attr = sym_new_not_null(ctx);
self_or_null = sym_new_unknown(ctx);
stack_pointer[-1] = attr;
stack_pointer[0] = self_or_null;
case _INSERT_NULL: {
JitOptSymbol *self;
JitOptSymbol **method_and_self;
self = stack_pointer[-1];
method_and_self = &stack_pointer[-1];
method_and_self[0] = sym_new_null(ctx);
method_and_self[1] = self;
stack_pointer += 1;
assert(WITHIN_STACK_BOUNDS());
break;
}
case _LOAD_SPECIAL: {
JitOptSymbol **method_and_self;
method_and_self = &stack_pointer[-2];
method_and_self[0] = sym_new_not_null(ctx);
method_and_self[1] = sym_new_unknown(ctx);
break;
}
case _WITH_EXCEPT_START: {
JitOptSymbol *res;
res = sym_new_not_null(ctx);