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bpo-33608: Use _Py_AddPendingCall() in _PyCrossInterpreterData_Release(). #12024

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Merged
merged 5 commits into from
Mar 1, 2019
Merged

bpo-33608: Use _Py_AddPendingCall() in _PyCrossInterpreterData_Release(). #12024

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416c522
Use _Py_AddPendingCall() for releasing shared data.
ericsnowcurrently Sep 14, 2018
466c0d9
Lock "HEAD" around looking up intepreter by ID.
ericsnowcurrently Jan 28, 2019
e99a90b
Check the result of adding the pending call (for releasing XID).
ericsnowcurrently Jan 28, 2019
652413a
Make a copy of data-to-be-deleted.
ericsnowcurrently Jan 29, 2019
2bc3cd0
Make a function static.
ericsnowcurrently Feb 26, 2019
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81 changes: 42 additions & 39 deletions Python/pystate.c
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Original file line number Diff line number Diff line change
Expand Up @@ -327,28 +327,39 @@ PyInterpreterState_GetID(PyInterpreterState *interp)
}


PyInterpreterState *
_PyInterpreterState_LookUpID(PY_INT64_T requested_id)
static PyInterpreterState *
interp_look_up_id(PY_INT64_T requested_id)
{
if (requested_id < 0)
goto error;

PyInterpreterState *interp = PyInterpreterState_Head();
while (interp != NULL) {
PY_INT64_T id = PyInterpreterState_GetID(interp);
if (id < 0)
if (id < 0) {
return NULL;
if (requested_id == id)
}
if (requested_id == id) {
return interp;
}
interp = PyInterpreterState_Next(interp);
}

error:
PyErr_Format(PyExc_RuntimeError,
"unrecognized interpreter ID %lld", requested_id);
return NULL;
}

PyInterpreterState *
_PyInterpreterState_LookUpID(PY_INT64_T requested_id)
{
PyInterpreterState *interp = NULL;
if (requested_id >= 0) {
HEAD_UNLOCK();
interp = interp_look_up_id(requested_id);
HEAD_UNLOCK();
}
if (interp == NULL && !PyErr_Occurred()) {
PyErr_Format(PyExc_RuntimeError,
"unrecognized interpreter ID %lld", requested_id);
}
return interp;
}


int
_PyInterpreterState_IDInitref(PyInterpreterState *interp)
Expand Down Expand Up @@ -1279,38 +1290,16 @@ _PyObject_GetCrossInterpreterData(PyObject *obj, _PyCrossInterpreterData *data)
return 0;
}

static void
static int
_release_xidata(void *arg)
{
_PyCrossInterpreterData *data = (_PyCrossInterpreterData *)arg;
if (data->free != NULL) {
data->free(data->data);
}
Py_XDECREF(data->obj);
}

static void
_call_in_interpreter(PyInterpreterState *interp,
void (*func)(void *), void *arg)
{
/* We would use Py_AddPendingCall() if it weren't specific to the
* main interpreter (see bpo-33608). In the meantime we take a
* naive approach.
*/
PyThreadState *save_tstate = NULL;
if (interp != _PyInterpreterState_Get()) {
// XXX Using the "head" thread isn't strictly correct.
PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
// XXX Possible GILState issues?
save_tstate = PyThreadState_Swap(tstate);
}

func(arg);

// Switch back.
if (save_tstate != NULL) {
PyThreadState_Swap(save_tstate);
}
PyMem_Free(data);
return 0;
}

void
Expand All @@ -1321,7 +1310,7 @@ _PyCrossInterpreterData_Release(_PyCrossInterpreterData *data)
return;
}

// Switch to the original interpreter.
// Get the original interpreter.
PyInterpreterState *interp = _PyInterpreterState_LookUpID(data->interp);
if (interp == NULL) {
// The intepreter was already destroyed.
Expand All @@ -1330,10 +1319,24 @@ _PyCrossInterpreterData_Release(_PyCrossInterpreterData *data)
}
return;
}
// XXX There's an ever-so-slight race here...
if (interp->finalizing) {
// XXX Someone leaked some memory...
return;
}

// "Release" the data and/or the object.
// XXX Use _Py_AddPendingCall().
_call_in_interpreter(interp, _release_xidata, data);
_PyCrossInterpreterData *copied = PyMem_Malloc(sizeof(_PyCrossInterpreterData));
if (copied == NULL) {
PyErr_SetString(PyExc_MemoryError,
"Not enough memory to preserve cross-interpreter data");
PyErr_Print();
return;
}
memcpy(copied, data, sizeof(_PyCrossInterpreterData));
if (_Py_AddPendingCall(interp, 0, _release_xidata, copied) != 0) {
// XXX Queue full or couldn't get lock. Try again somehow?
}
}

PyObject *
Expand Down