From 40322e6ad5f705e294ded37fa4a682f065ec80a2 Mon Sep 17 00:00:00 2001
From: Antoine Pitrou <solipsis@pitrou.net>
Date: Sun, 11 Aug 2013 00:30:09 +0200
Subject: [PATCH] Issue #10241: Clear extension module dict copies at
 interpreter shutdown. Patch by Neil Schemenauer, minimally modified.

(re-apply after fix for tkinter-related crash)
---
 Include/pystate.h |  3 +++
 Misc/NEWS         |  3 +++
 Python/import.c   |  2 ++
 Python/pystate.c  | 25 +++++++++++++++++++++++++
 4 files changed, 33 insertions(+)

diff --git a/Include/pystate.h b/Include/pystate.h
index cd1d7765be0..e41fe4c0d5f 100644
--- a/Include/pystate.h
+++ b/Include/pystate.h
@@ -134,6 +134,9 @@ PyAPI_FUNC(int) PyState_AddModule(PyObject*, struct PyModuleDef*);
 PyAPI_FUNC(int) PyState_RemoveModule(struct PyModuleDef*);
 #endif
 PyAPI_FUNC(PyObject*) PyState_FindModule(struct PyModuleDef*);
+#ifndef Py_LIMITED_API
+PyAPI_FUNC(void) _PyState_ClearModules(void);
+#endif
 
 PyAPI_FUNC(PyThreadState *) PyThreadState_New(PyInterpreterState *);
 PyAPI_FUNC(PyThreadState *) _PyThreadState_Prealloc(PyInterpreterState *);
diff --git a/Misc/NEWS b/Misc/NEWS
index 1bbb17e29fb..d8476625e9b 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -54,6 +54,9 @@ Core and Builtins
 
 - Issue #17899: Fix rare file descriptor leak in os.listdir().
 
+- Issue #10241: Clear extension module dict copies at interpreter shutdown.
+  Patch by Neil Schemenauer, minimally modified.
+
 - Issue #9035: ismount now recognises volumes mounted below a drive root
   on Windows. Original patch by Atsuo Ishimoto.
 
diff --git a/Python/import.c b/Python/import.c
index be73d4bba82..113123d5649 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -380,6 +380,8 @@ PyImport_Cleanup(void)
     builtins = interp->builtins;
     interp->builtins = PyDict_New();
     Py_DECREF(builtins);
+    /* Clear module dict copies stored in the interpreter state */
+    _PyState_ClearModules();
     /* Collect references */
     _PyGC_CollectNoFail();
     /* Dump GC stats before it's too late, since it uses the warnings
diff --git a/Python/pystate.c b/Python/pystate.c
index 40606bf1ca7..924b6a29090 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -320,6 +320,31 @@ PyState_RemoveModule(struct PyModuleDef* def)
     return PyList_SetItem(state->modules_by_index, index, Py_None);
 }
 
+/* used by import.c:PyImport_Cleanup */
+void
+_PyState_ClearModules(void)
+{
+    PyInterpreterState *state = PyThreadState_GET()->interp;
+    if (state->modules_by_index) {
+        Py_ssize_t i;
+        for (i = 0; i < PyList_GET_SIZE(state->modules_by_index); i++) {
+            PyObject *m = PyList_GET_ITEM(state->modules_by_index, i);
+            if (PyModule_Check(m)) {
+                /* cleanup the saved copy of module dicts */
+                PyModuleDef *md = PyModule_GetDef(m);
+                if (md)
+                    Py_CLEAR(md->m_base.m_copy);
+            }
+        }
+        /* Setting modules_by_index to NULL could be dangerous, so we
+           clear the list instead. */
+        if (PyList_SetSlice(state->modules_by_index,
+                            0, PyList_GET_SIZE(state->modules_by_index),
+                            NULL))
+            PyErr_WriteUnraisable(state->modules_by_index);
+    }
+}
+
 void
 PyThreadState_Clear(PyThreadState *tstate)
 {