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Extract gil management functions to separate header (#2845)

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Dustin Spicuzza 2021-02-22 22:15:40 -05:00 committed by GitHub
parent 0c42250a4e
commit c0fbb02c9f
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4 changed files with 196 additions and 167 deletions
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1
CMakeLists.txt
View File

@ -117,6 +117,7 @@ set(PYBIND11_HEADERS
include/pybind11/eigen.h
include/pybind11/embed.h
include/pybind11/eval.h
include/pybind11/gil.h
include/pybind11/iostream.h
include/pybind11/functional.h
include/pybind11/numpy.h

193
include/pybind11/gil.h Normal file
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@ -0,0 +1,193 @@
/*
pybind11/gil.h: RAII helpers for managing the GIL
Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
All rights reserved. Use of this source code is governed by a
BSD-style license that can be found in the LICENSE file.
*/
#pragma once
#include "detail/common.h"
#include "detail/internals.h"
PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
PYBIND11_NAMESPACE_BEGIN(detail)
// forward declarations
PyThreadState *get_thread_state_unchecked();
PYBIND11_NAMESPACE_END(detail)
#if defined(WITH_THREAD) && !defined(PYPY_VERSION)
/* The functions below essentially reproduce the PyGILState_* API using a RAII
* pattern, but there are a few important differences:
*
* 1. When acquiring the GIL from an non-main thread during the finalization
* phase, the GILState API blindly terminates the calling thread, which
* is often not what is wanted. This API does not do this.
*
* 2. The gil_scoped_release function can optionally cut the relationship
* of a PyThreadState and its associated thread, which allows moving it to
* another thread (this is a fairly rare/advanced use case).
*
* 3. The reference count of an acquired thread state can be controlled. This
* can be handy to prevent cases where callbacks issued from an external
* thread would otherwise constantly construct and destroy thread state data
* structures.
*
* See the Python bindings of NanoGUI (http://github.com/wjakob/nanogui) for an
* example which uses features 2 and 3 to migrate the Python thread of
* execution to another thread (to run the event loop on the original thread,
* in this case).
*/
class gil_scoped_acquire {
public:
PYBIND11_NOINLINE gil_scoped_acquire() {
auto const &internals = detail::get_internals();
tstate = (PyThreadState *) PYBIND11_TLS_GET_VALUE(internals.tstate);
if (!tstate) {
/* Check if the GIL was acquired using the PyGILState_* API instead (e.g. if
calling from a Python thread). Since we use a different key, this ensures
we don't create a new thread state and deadlock in PyEval_AcquireThread
below. Note we don't save this state with internals.tstate, since we don't
create it we would fail to clear it (its reference count should be > 0). */
tstate = PyGILState_GetThisThreadState();
}
if (!tstate) {
tstate = PyThreadState_New(internals.istate);
#if !defined(NDEBUG)
if (!tstate)
pybind11_fail("scoped_acquire: could not create thread state!");
#endif
tstate->gilstate_counter = 0;
PYBIND11_TLS_REPLACE_VALUE(internals.tstate, tstate);
} else {
release = detail::get_thread_state_unchecked() != tstate;
}
if (release) {
PyEval_AcquireThread(tstate);
}
inc_ref();
}
void inc_ref() {
++tstate->gilstate_counter;
}
PYBIND11_NOINLINE void dec_ref() {
--tstate->gilstate_counter;
#if !defined(NDEBUG)
if (detail::get_thread_state_unchecked() != tstate)
pybind11_fail("scoped_acquire::dec_ref(): thread state must be current!");
if (tstate->gilstate_counter < 0)
pybind11_fail("scoped_acquire::dec_ref(): reference count underflow!");
#endif
if (tstate->gilstate_counter == 0) {
#if !defined(NDEBUG)
if (!release)
pybind11_fail("scoped_acquire::dec_ref(): internal error!");
#endif
PyThreadState_Clear(tstate);
if (active)
PyThreadState_DeleteCurrent();
PYBIND11_TLS_DELETE_VALUE(detail::get_internals().tstate);
release = false;
}
}
/// This method will disable the PyThreadState_DeleteCurrent call and the
/// GIL won't be acquired. This method should be used if the interpreter
/// could be shutting down when this is called, as thread deletion is not
/// allowed during shutdown. Check _Py_IsFinalizing() on Python 3.7+, and
/// protect subsequent code.
PYBIND11_NOINLINE void disarm() {
active = false;
}
PYBIND11_NOINLINE ~gil_scoped_acquire() {
dec_ref();
if (release)
PyEval_SaveThread();
}
private:
PyThreadState *tstate = nullptr;
bool release = true;
bool active = true;
};
class gil_scoped_release {
public:
explicit gil_scoped_release(bool disassoc = false) : disassoc(disassoc) {
// `get_internals()` must be called here unconditionally in order to initialize
// `internals.tstate` for subsequent `gil_scoped_acquire` calls. Otherwise, an
// initialization race could occur as multiple threads try `gil_scoped_acquire`.
const auto &internals = detail::get_internals();
tstate = PyEval_SaveThread();
if (disassoc) {
auto key = internals.tstate;
PYBIND11_TLS_DELETE_VALUE(key);
}
}
/// This method will disable the PyThreadState_DeleteCurrent call and the
/// GIL won't be acquired. This method should be used if the interpreter
/// could be shutting down when this is called, as thread deletion is not
/// allowed during shutdown. Check _Py_IsFinalizing() on Python 3.7+, and
/// protect subsequent code.
PYBIND11_NOINLINE void disarm() {
active = false;
}
~gil_scoped_release() {
if (!tstate)
return;
// `PyEval_RestoreThread()` should not be called if runtime is finalizing
if (active)
PyEval_RestoreThread(tstate);
if (disassoc) {
auto key = detail::get_internals().tstate;
PYBIND11_TLS_REPLACE_VALUE(key, tstate);
}
}
private:
PyThreadState *tstate;
bool disassoc;
bool active = true;
};
#elif defined(PYPY_VERSION)
class gil_scoped_acquire {
PyGILState_STATE state;
public:
gil_scoped_acquire() { state = PyGILState_Ensure(); }
~gil_scoped_acquire() { PyGILState_Release(state); }
void disarm() {}
};
class gil_scoped_release {
PyThreadState *state;
public:
gil_scoped_release() { state = PyEval_SaveThread(); }
~gil_scoped_release() { PyEval_RestoreThread(state); }
void disarm() {}
};
#else
class gil_scoped_acquire {
void disarm() {}
};
class gil_scoped_release {
void disarm() {}
};
#endif
PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

168
include/pybind11/pybind11.h
View File

@ -43,6 +43,7 @@
#endif
#include "attr.h"
#include "gil.h"
#include "options.h"
#include "detail/class.h"
#include "detail/init.h"
@ -2091,173 +2092,6 @@ void print(Args &&...args) {
detail::print(c.args(), c.kwargs());
}
#if defined(WITH_THREAD) && !defined(PYPY_VERSION)
/* The functions below essentially reproduce the PyGILState_* API using a RAII
* pattern, but there are a few important differences:
*
* 1. When acquiring the GIL from an non-main thread during the finalization
* phase, the GILState API blindly terminates the calling thread, which
* is often not what is wanted. This API does not do this.
*
* 2. The gil_scoped_release function can optionally cut the relationship
* of a PyThreadState and its associated thread, which allows moving it to
* another thread (this is a fairly rare/advanced use case).
*
* 3. The reference count of an acquired thread state can be controlled. This
* can be handy to prevent cases where callbacks issued from an external
* thread would otherwise constantly construct and destroy thread state data
* structures.
*
* See the Python bindings of NanoGUI (http://github.com/wjakob/nanogui) for an
* example which uses features 2 and 3 to migrate the Python thread of
* execution to another thread (to run the event loop on the original thread,
* in this case).
*/
class gil_scoped_acquire {
public:
PYBIND11_NOINLINE gil_scoped_acquire() {
auto const &internals = detail::get_internals();
tstate = (PyThreadState *) PYBIND11_TLS_GET_VALUE(internals.tstate);
if (!tstate) {
/* Check if the GIL was acquired using the PyGILState_* API instead (e.g. if
calling from a Python thread). Since we use a different key, this ensures
we don't create a new thread state and deadlock in PyEval_AcquireThread
below. Note we don't save this state with internals.tstate, since we don't
create it we would fail to clear it (its reference count should be > 0). */
tstate = PyGILState_GetThisThreadState();
}
if (!tstate) {
tstate = PyThreadState_New(internals.istate);
#if !defined(NDEBUG)
if (!tstate)
pybind11_fail("scoped_acquire: could not create thread state!");
#endif
tstate->gilstate_counter = 0;
PYBIND11_TLS_REPLACE_VALUE(internals.tstate, tstate);
} else {
release = detail::get_thread_state_unchecked() != tstate;
}
if (release) {
PyEval_AcquireThread(tstate);
}
inc_ref();
}
void inc_ref() {
++tstate->gilstate_counter;
}
PYBIND11_NOINLINE void dec_ref() {
--tstate->gilstate_counter;
#if !defined(NDEBUG)
if (detail::get_thread_state_unchecked() != tstate)
pybind11_fail("scoped_acquire::dec_ref(): thread state must be current!");
if (tstate->gilstate_counter < 0)
pybind11_fail("scoped_acquire::dec_ref(): reference count underflow!");
#endif
if (tstate->gilstate_counter == 0) {
#if !defined(NDEBUG)
if (!release)
pybind11_fail("scoped_acquire::dec_ref(): internal error!");
#endif
PyThreadState_Clear(tstate);
if (active)
PyThreadState_DeleteCurrent();
PYBIND11_TLS_DELETE_VALUE(detail::get_internals().tstate);
release = false;
}
}
/// This method will disable the PyThreadState_DeleteCurrent call and the
/// GIL won't be acquired. This method should be used if the interpreter
/// could be shutting down when this is called, as thread deletion is not
/// allowed during shutdown. Check _Py_IsFinalizing() on Python 3.7+, and
/// protect subsequent code.
PYBIND11_NOINLINE void disarm() {
active = false;
}
PYBIND11_NOINLINE ~gil_scoped_acquire() {
dec_ref();
if (release)
PyEval_SaveThread();
}
private:
PyThreadState *tstate = nullptr;
bool release = true;
bool active = true;
};
class gil_scoped_release {
public:
explicit gil_scoped_release(bool disassoc = false) : disassoc(disassoc) {
// `get_internals()` must be called here unconditionally in order to initialize
// `internals.tstate` for subsequent `gil_scoped_acquire` calls. Otherwise, an
// initialization race could occur as multiple threads try `gil_scoped_acquire`.
const auto &internals = detail::get_internals();
tstate = PyEval_SaveThread();
if (disassoc) {
auto key = internals.tstate;
PYBIND11_TLS_DELETE_VALUE(key);
}
}
/// This method will disable the PyThreadState_DeleteCurrent call and the
/// GIL won't be acquired. This method should be used if the interpreter
/// could be shutting down when this is called, as thread deletion is not
/// allowed during shutdown. Check _Py_IsFinalizing() on Python 3.7+, and
/// protect subsequent code.
PYBIND11_NOINLINE void disarm() {
active = false;
}
~gil_scoped_release() {
if (!tstate)
return;
// `PyEval_RestoreThread()` should not be called if runtime is finalizing
if (active)
PyEval_RestoreThread(tstate);
if (disassoc) {
auto key = detail::get_internals().tstate;
PYBIND11_TLS_REPLACE_VALUE(key, tstate);
}
}
private:
PyThreadState *tstate;
bool disassoc;
bool active = true;
};
#elif defined(PYPY_VERSION)
class gil_scoped_acquire {
PyGILState_STATE state;
public:
gil_scoped_acquire() { state = PyGILState_Ensure(); }
~gil_scoped_acquire() { PyGILState_Release(state); }
void disarm() {}
};
class gil_scoped_release {
PyThreadState *state;
public:
gil_scoped_release() { state = PyEval_SaveThread(); }
~gil_scoped_release() { PyEval_RestoreThread(state); }
void disarm() {}
};
#else
class gil_scoped_acquire {
void disarm() {}
};
class gil_scoped_release {
void disarm() {}
};
#endif
error_already_set::~error_already_set() {
if (m_type) {
gil_scoped_acquire gil;

1
tests/extra_python_package/test_files.py
View File

@ -25,6 +25,7 @@ main_headers = {
"include/pybind11/embed.h",
"include/pybind11/eval.h",
"include/pybind11/functional.h",
"include/pybind11/gil.h",
"include/pybind11/iostream.h",
"include/pybind11/numpy.h",
"include/pybind11/operators.h",