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fix: support free-threaded CPython with GIL disabled (pybind#5148)
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* Support free-threaded CPython (PEP 703)

Some additional locking is added in the free-threaded build when
`Py_GIL_DISABLED` is defined:

- Most accesses to internals are protected by a single mutex
- The registered_instances uses a striped lock to improve concurrency

Pybind11 modules can indicate support for running with the GIL disabled
by calling `set_gil_not_used()`.

* refactor: use PYBIND11_MODULE (#11)

Signed-off-by: Henry Schreiner <[email protected]>

* Address code review

* Suppress MSVC warning

* Changes from review

* style: pre-commit fixes

* `py::mod_gil_not_used()` suggestion.

* Update include/pybind11/pybind11.h

---------

Signed-off-by: Henry Schreiner <[email protected]>
Co-authored-by: Henry Schreiner <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Ralf W. Grosse-Kunstleve <[email protected]>
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@colesbury @henryiii @pre-commit-ci
4 people authored Jun 18, 2024
1 parent 1961b96 commit baa540e
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Showing 15 changed files with 356 additions and 141 deletions.
116 changes: 63 additions & 53 deletions include/pybind11/detail/class.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -205,39 +205,40 @@ extern "C" inline PyObject *pybind11_meta_call(PyObject *type, PyObject *args, P

/// Cleanup the type-info for a pybind11-registered type.
extern "C" inline void pybind11_meta_dealloc(PyObject *obj) {
auto *type = (PyTypeObject *) obj;
auto &internals = get_internals();

// A pybind11-registered type will:
// 1) be found in internals.registered_types_py
// 2) have exactly one associated `detail::type_info`
auto found_type = internals.registered_types_py.find(type);
if (found_type != internals.registered_types_py.end() && found_type->second.size() == 1
&& found_type->second[0]->type == type) {

auto *tinfo = found_type->second[0];
auto tindex = std::type_index(*tinfo->cpptype);
internals.direct_conversions.erase(tindex);

if (tinfo->module_local) {
get_local_internals().registered_types_cpp.erase(tindex);
} else {
internals.registered_types_cpp.erase(tindex);
}
internals.registered_types_py.erase(tinfo->type);

// Actually just `std::erase_if`, but that's only available in C++20
auto &cache = internals.inactive_override_cache;
for (auto it = cache.begin(), last = cache.end(); it != last;) {
if (it->first == (PyObject *) tinfo->type) {
it = cache.erase(it);
with_internals([obj](internals &internals) {
auto *type = (PyTypeObject *) obj;

// A pybind11-registered type will:
// 1) be found in internals.registered_types_py
// 2) have exactly one associated `detail::type_info`
auto found_type = internals.registered_types_py.find(type);
if (found_type != internals.registered_types_py.end() && found_type->second.size() == 1
&& found_type->second[0]->type == type) {

auto *tinfo = found_type->second[0];
auto tindex = std::type_index(*tinfo->cpptype);
internals.direct_conversions.erase(tindex);

if (tinfo->module_local) {
get_local_internals().registered_types_cpp.erase(tindex);
} else {
++it;
internals.registered_types_cpp.erase(tindex);
}
internals.registered_types_py.erase(tinfo->type);

// Actually just `std::erase_if`, but that's only available in C++20
auto &cache = internals.inactive_override_cache;
for (auto it = cache.begin(), last = cache.end(); it != last;) {
if (it->first == (PyObject *) tinfo->type) {
it = cache.erase(it);
} else {
++it;
}
}
}

delete tinfo;
}
delete tinfo;
}
});

PyType_Type.tp_dealloc(obj);
}
Expand Down Expand Up @@ -310,19 +311,20 @@ inline void traverse_offset_bases(void *valueptr,
}

inline bool register_instance_impl(void *ptr, instance *self) {
get_internals().registered_instances.emplace(ptr, self);
with_instance_map(ptr, [&](instance_map &instances) { instances.emplace(ptr, self); });
return true; // unused, but gives the same signature as the deregister func
}
inline bool deregister_instance_impl(void *ptr, instance *self) {
auto &registered_instances = get_internals().registered_instances;
auto range = registered_instances.equal_range(ptr);
for (auto it = range.first; it != range.second; ++it) {
if (self == it->second) {
registered_instances.erase(it);
return true;
return with_instance_map(ptr, [&](instance_map &instances) {
auto range = instances.equal_range(ptr);
for (auto it = range.first; it != range.second; ++it) {
if (self == it->second) {
instances.erase(it);
return true;
}
}
}
return false;
return false;
});
}

inline void register_instance(instance *self, void *valptr, const type_info *tinfo) {
Expand Down Expand Up @@ -377,27 +379,32 @@ extern "C" inline int pybind11_object_init(PyObject *self, PyObject *, PyObject
}

inline void add_patient(PyObject *nurse, PyObject *patient) {
auto &internals = get_internals();
auto *instance = reinterpret_cast<detail::instance *>(nurse);
instance->has_patients = true;
Py_INCREF(patient);
internals.patients[nurse].push_back(patient);

with_internals([&](internals &internals) { internals.patients[nurse].push_back(patient); });
}

inline void clear_patients(PyObject *self) {
auto *instance = reinterpret_cast<detail::instance *>(self);
auto &internals = get_internals();
auto pos = internals.patients.find(self);
std::vector<PyObject *> patients;

if (pos == internals.patients.end()) {
pybind11_fail("FATAL: Internal consistency check failed: Invalid clear_patients() call.");
}
with_internals([&](internals &internals) {
auto pos = internals.patients.find(self);

if (pos == internals.patients.end()) {
pybind11_fail(
"FATAL: Internal consistency check failed: Invalid clear_patients() call.");
}

// Clearing the patients can cause more Python code to run, which
// can invalidate the iterator. Extract the vector of patients
// from the unordered_map first.
patients = std::move(pos->second);
internals.patients.erase(pos);
});

// Clearing the patients can cause more Python code to run, which
// can invalidate the iterator. Extract the vector of patients
// from the unordered_map first.
auto patients = std::move(pos->second);
internals.patients.erase(pos);
instance->has_patients = false;
for (PyObject *&patient : patients) {
Py_CLEAR(patient);
Expand Down Expand Up @@ -662,10 +669,13 @@ inline PyObject *make_new_python_type(const type_record &rec) {

char *tp_doc = nullptr;
if (rec.doc && options::show_user_defined_docstrings()) {
/* Allocate memory for docstring (using PyObject_MALLOC, since
Python will free this later on) */
/* Allocate memory for docstring (Python will free this later on) */
size_t size = std::strlen(rec.doc) + 1;
#if PY_VERSION_HEX >= 0x030D0000
tp_doc = (char *) PyMem_MALLOC(size);
#else
tp_doc = (char *) PyObject_MALLOC(size);
#endif
std::memcpy((void *) tp_doc, rec.doc, size);
}

Expand Down
7 changes: 5 additions & 2 deletions include/pybind11/detail/common.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -464,7 +464,7 @@ PYBIND11_WARNING_POP
});
}
\endrst */
#define PYBIND11_MODULE(name, variable) \
#define PYBIND11_MODULE(name, variable, ...) \
static ::pybind11::module_::module_def PYBIND11_CONCAT(pybind11_module_def_, name) \
PYBIND11_MAYBE_UNUSED; \
PYBIND11_MAYBE_UNUSED \
Expand All @@ -473,7 +473,10 @@ PYBIND11_WARNING_POP
PYBIND11_CHECK_PYTHON_VERSION \
PYBIND11_ENSURE_INTERNALS_READY \
auto m = ::pybind11::module_::create_extension_module( \
PYBIND11_TOSTRING(name), nullptr, &PYBIND11_CONCAT(pybind11_module_def_, name)); \
PYBIND11_TOSTRING(name), \
nullptr, \
&PYBIND11_CONCAT(pybind11_module_def_, name), \
##__VA_ARGS__); \
try { \
PYBIND11_CONCAT(pybind11_init_, name)(m); \
return m.ptr(); \
Expand Down
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