bpo-33331: Clean modules in the reversed order in PyImport_Cleanup().

serhiy-storchaka · serhiy-storchaka · commit 60187406b04f · 2018-10-01T16:31:34.000+03:00
Modules imported last are now cleared first at interpreter shutdown.
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-04-22-13-41-59.bpo-33331.s_DxdL.rst b/Misc/NEWS.d/next/Core and Builtins/2018-04-22-13-41-59.bpo-33331.s_DxdL.rst
@@ -0,0 +1 @@
+Modules imported last are now cleared first at interpreter shutdown.
diff --git a/Python/import.c b/Python/import.c
@@ -543,9 +543,10 @@ PyImport_Cleanup(void)
        module last.  Likewise, we don't delete sys until the very
        end because it is implicitly referenced (e.g. by print). */
     if (weaklist != NULL) {
-        Py_ssize_t i, n;
-        n = PyList_GET_SIZE(weaklist);
-        for (i = 0; i < n; i++) {
+        Py_ssize_t i;
+        /* Since dict is ordered in CPython 3.6+, modules are saved in
+           importing order.  First clear modules imported later. */
+        for (i = PyList_GET_SIZE(weaklist) - 1; i >= 0; i--) {
             PyObject *tup = PyList_GET_ITEM(weaklist, i);
             PyObject *name = PyTuple_GET_ITEM(tup, 0);
             PyObject *mod = PyWeakref_GET_OBJECT(PyTuple_GET_ITEM(tup, 1));

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+Modules imported last are now cleared first at interpreter shutdown.`