bpo-36475: Finalize PyEval_AcquireLock() and PyEval_AcquireThread() properly (GH-12667)

PyEval_AcquireLock() and PyEval_AcquireThread() now
terminate the current thread if called while the interpreter is
finalizing, making them consistent with PyEval_RestoreThread(),
Py_END_ALLOW_THREADS, and PyGILState_Ensure().
This commit is contained in:
Joannah Nanjekye 2019-04-29 04:38:45 -04:00 committed by Victor Stinner
parent 254b309c80
commit f781d202a2
4 changed files with 51 additions and 12 deletions

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@ -1080,6 +1080,18 @@ All of the following functions must be called after :c:func:`Py_Initialize`.
*tstate*, which should not be *NULL*. The lock must have been created earlier.
If this thread already has the lock, deadlock ensues.
.. note::
Calling this function from a thread when the runtime is finalizing
will terminate the thread, even if the thread was not created by Python.
You can use :c:func:`_Py_IsFinalizing` or :func:`sys.is_finalizing` to
check if the interpreter is in process of being finalized before calling
this function to avoid unwanted termination.
.. versionchanged:: 3.8
Updated to be consistent with :c:func:`PyEval_RestoreThread`,
:c:func:`Py_END_ALLOW_THREADS`, and :c:func:`PyGILState_Ensure`,
and terminate the current thread if called while the interpreter is finalizing.
:c:func:`PyEval_RestoreThread` is a higher-level function which is always
available (even when threads have not been initialized).
@ -1106,6 +1118,18 @@ All of the following functions must be called after :c:func:`Py_Initialize`.
:c:func:`PyEval_RestoreThread` or :c:func:`PyEval_AcquireThread`
instead.
.. note::
Calling this function from a thread when the runtime is finalizing
will terminate the thread, even if the thread was not created by Python.
You can use :c:func:`_Py_IsFinalizing` or :func:`sys.is_finalizing` to
check if the interpreter is in process of being finalized before calling
this function to avoid unwanted termination.
.. versionchanged:: 3.8
Updated to be consistent with :c:func:`PyEval_RestoreThread`,
:c:func:`Py_END_ALLOW_THREADS`, and :c:func:`PyGILState_Ensure`,
and terminate the current thread if called while the interpreter is finalizing.
.. c:function:: void PyEval_ReleaseLock()

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@ -758,6 +758,13 @@ Changes in Python behavior
always use the ``sys.platform.startswith('aix')``.
(Contributed by M. Felt in :issue:`36588`.)
* :c:func:`PyEval_AcquireLock` and :c:func:`PyEval_AcquireThread` now
terminate the current thread if called while the interpreter is
finalizing, making them consistent with :c:func:`PyEval_RestoreThread`,
:c:func:`Py_END_ALLOW_THREADS`, and :c:func:`PyGILState_Ensure`. If this
behaviour is not desired, guard the call by checking :c:func:`_Py_IsFinalizing`
or :c:func:`sys.is_finalizing`.
Changes in the Python API
-------------------------

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@ -0,0 +1,4 @@
:c:func:`PyEval_AcquireLock` and :c:func:`PyEval_AcquireThread` now
terminate the current thread if called while the interpreter is
finalizing, making them consistent with :c:func:`PyEval_RestoreThread`,
:c:func:`Py_END_ALLOW_THREADS`, and :c:func:`PyGILState_Ensure`.

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@ -76,6 +76,7 @@ static PyObject * special_lookup(PyObject *, _Py_Identifier *);
static int check_args_iterable(PyObject *func, PyObject *vararg);
static void format_kwargs_error(PyObject *func, PyObject *kwargs);
static void format_awaitable_error(PyTypeObject *, int);
static inline void exit_thread_if_finalizing(PyThreadState *);
#define NAME_ERROR_MSG \
"name '%.200s' is not defined"
@ -203,6 +204,17 @@ _PyEval_FiniThreads(void)
}
}
static inline void
exit_thread_if_finalizing(PyThreadState *tstate)
{
/* _Py_Finalizing is protected by the GIL */
if (_Py_IsFinalizing() && !_Py_CURRENTLY_FINALIZING(tstate)) {
drop_gil(tstate);
PyThread_exit_thread();
Py_UNREACHABLE();
}
}
void
PyEval_AcquireLock(void)
{
@ -210,6 +222,7 @@ PyEval_AcquireLock(void)
if (tstate == NULL)
Py_FatalError("PyEval_AcquireLock: current thread state is NULL");
take_gil(tstate);
exit_thread_if_finalizing(tstate);
}
void
@ -230,6 +243,7 @@ PyEval_AcquireThread(PyThreadState *tstate)
/* Check someone has called PyEval_InitThreads() to create the lock */
assert(gil_created());
take_gil(tstate);
exit_thread_if_finalizing(tstate);
if (PyThreadState_Swap(tstate) != NULL)
Py_FatalError(
"PyEval_AcquireThread: non-NULL old thread state");
@ -298,12 +312,7 @@ PyEval_RestoreThread(PyThreadState *tstate)
int err = errno;
take_gil(tstate);
/* _Py_Finalizing is protected by the GIL */
if (_Py_IsFinalizing() && !_Py_CURRENTLY_FINALIZING(tstate)) {
drop_gil(tstate);
PyThread_exit_thread();
Py_UNREACHABLE();
}
exit_thread_if_finalizing(tstate);
errno = err;
PyThreadState_Swap(tstate);
@ -1083,12 +1092,7 @@ main_loop:
take_gil(tstate);
/* Check if we should make a quick exit. */
if (_Py_IsFinalizing() &&
!_Py_CURRENTLY_FINALIZING(tstate))
{
drop_gil(tstate);
PyThread_exit_thread();
}
exit_thread_if_finalizing(tstate);
if (PyThreadState_Swap(tstate) != NULL)
Py_FatalError("ceval: orphan tstate");