bpo-31558: Add gc.freeze() (#3705)
Freeze all the objects tracked by gc - move them to a permanent generation
and ignore all the future collections. This can be used before a POSIX
fork() call to make the gc copy-on-write friendly or to speed up collection.
diff --git a/Modules/clinic/gcmodule.c.h b/Modules/clinic/gcmodule.c.h
index 771c573..c31ef65 100644
--- a/Modules/clinic/gcmodule.c.h
+++ b/Modules/clinic/gcmodule.c.h
@@ -255,4 +255,74 @@
#define GC_IS_TRACKED_METHODDEF \
{"is_tracked", (PyCFunction)gc_is_tracked, METH_O, gc_is_tracked__doc__},
-/*[clinic end generated code: output=5a58583f00ab018e input=a9049054013a1b77]*/
+
+PyDoc_STRVAR(gc_freeze__doc__,
+"freeze($module, /)\n"
+"--\n"
+"\n"
+"Freeze all current tracked objects and ignore them for future collections.\n"
+"\n"
+"This can be used before a POSIX fork() call to make the gc copy-on-write friendly.\n"
+"Note: collection before a POSIX fork() call may free pages for future allocation\n"
+"which can cause copy-on-write.");
+
+#define GC_FREEZE_METHODDEF \
+ {"freeze", (PyCFunction)gc_freeze, METH_NOARGS, gc_freeze__doc__},
+
+static PyObject *
+gc_freeze_impl(PyObject *module);
+
+static PyObject *
+gc_freeze(PyObject *module, PyObject *Py_UNUSED(ignored))
+{
+ return gc_freeze_impl(module);
+}
+
+PyDoc_STRVAR(gc_unfreeze__doc__,
+"unfreeze($module, /)\n"
+"--\n"
+"\n"
+"Unfreeze all objects in the permanent generation.\n"
+"\n"
+"Put all objects in the permanent generation back into oldest generation.");
+
+#define GC_UNFREEZE_METHODDEF \
+ {"unfreeze", (PyCFunction)gc_unfreeze, METH_NOARGS, gc_unfreeze__doc__},
+
+static PyObject *
+gc_unfreeze_impl(PyObject *module);
+
+static PyObject *
+gc_unfreeze(PyObject *module, PyObject *Py_UNUSED(ignored))
+{
+ return gc_unfreeze_impl(module);
+}
+
+PyDoc_STRVAR(gc_get_freeze_count__doc__,
+"get_freeze_count($module, /)\n"
+"--\n"
+"\n"
+"Return the number of objects in the permanent generation.");
+
+#define GC_GET_FREEZE_COUNT_METHODDEF \
+ {"get_freeze_count", (PyCFunction)gc_get_freeze_count, METH_NOARGS, gc_get_freeze_count__doc__},
+
+static int
+gc_get_freeze_count_impl(PyObject *module);
+
+static PyObject *
+gc_get_freeze_count(PyObject *module, PyObject *Py_UNUSED(ignored))
+{
+ PyObject *return_value = NULL;
+ int _return_value;
+
+ _return_value = gc_get_freeze_count_impl(module);
+ if ((_return_value == -1) && PyErr_Occurred()) {
+ goto exit;
+ }
+ return_value = PyLong_FromLong((long)_return_value);
+
+exit:
+ return return_value;
+}
+/*[clinic end generated code: output=4f41ec4588154f2b input=a9049054013a1b77]*/