Issue #17934: Add a clear() method to frame objects, to help clean up expensive details (local variables) and break reference cycles.
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index d3b59f1..a62a45e 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -488,7 +488,7 @@
}
static void
-frame_clear(PyFrameObject *f)
+frame_tp_clear(PyFrameObject *f)
{
PyObject **fastlocals, **p, **oldtop;
Py_ssize_t i, slots;
@@ -500,6 +500,7 @@
*/
oldtop = f->f_stacktop;
f->f_stacktop = NULL;
+ f->f_executing = 0;
Py_CLEAR(f->f_exc_type);
Py_CLEAR(f->f_exc_value);
@@ -520,6 +521,25 @@
}
static PyObject *
+frame_clear(PyFrameObject *f)
+{
+ if (f->f_executing) {
+ PyErr_SetString(PyExc_RuntimeError,
+ "cannot clear an executing frame");
+ return NULL;
+ }
+ if (f->f_gen) {
+ _PyGen_Finalize(f->f_gen);
+ assert(f->f_gen == NULL);
+ }
+ frame_tp_clear(f);
+ Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(clear__doc__,
+"F.clear(): clear most references held by the frame");
+
+static PyObject *
frame_sizeof(PyFrameObject *f)
{
Py_ssize_t res, extras, ncells, nfrees;
@@ -538,6 +558,8 @@
"F.__sizeof__() -> size of F in memory, in bytes");
static PyMethodDef frame_methods[] = {
+ {"clear", (PyCFunction)frame_clear, METH_NOARGS,
+ clear__doc__},
{"__sizeof__", (PyCFunction)frame_sizeof, METH_NOARGS,
sizeof__doc__},
{NULL, NULL} /* sentinel */
@@ -566,7 +588,7 @@
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
0, /* tp_doc */
(traverseproc)frame_traverse, /* tp_traverse */
- (inquiry)frame_clear, /* tp_clear */
+ (inquiry)frame_tp_clear, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
0, /* tp_iter */
@@ -708,6 +730,8 @@
f->f_lasti = -1;
f->f_lineno = code->co_firstlineno;
f->f_iblock = 0;
+ f->f_executing = 0;
+ f->f_gen = NULL;
_PyObject_GC_TRACK(f);
return f;