bpo-34610: Fixed iterator of multiprocessing.managers.DictProxy. (GH-9113)

(cherry picked from commit e0e5065dae)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Lib/multiprocessing/managers.py

@@ -1134,10 +1134,13 @@ class ListProxy(BaseListProxy):
 
 
 DictProxy = MakeProxyType('DictProxy', (
-    '__contains__', '__delitem__', '__getitem__', '__len__',
+    '__contains__', '__delitem__', '__getitem__', '__iter__', '__len__',
     '__setitem__', 'clear', 'copy', 'get', 'has_key', 'items',
     'keys', 'pop', 'popitem', 'setdefault', 'update', 'values'
     ))
+DictProxy._method_to_typeid_ = {
+    '__iter__': 'Iterator',
+    }
 
 
 ArrayProxy = MakeProxyType('ArrayProxy', (

Lib/test/_test_multiprocessing.py

@@ -2079,6 +2079,16 @@ class _TestContainers(BaseTestCase):
         a.append('hello')
         self.assertEqual(f[0][:], [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'hello'])
 
+    def test_list_iter(self):
+        a = self.list(list(range(10)))
+        it = iter(a)
+        self.assertEqual(list(it), list(range(10)))
+        self.assertEqual(list(it), [])  # exhausted
+        # list modified during iteration
+        it = iter(a)
+        a[0] = 100
+        self.assertEqual(next(it), 100)
+
     def test_list_proxy_in_list(self):
         a = self.list([self.list(range(3)) for _i in range(3)])
         self.assertEqual([inner[:] for inner in a], [[0, 1, 2]] * 3)
@@ -2109,6 +2119,19 @@ class _TestContainers(BaseTestCase):
         self.assertEqual(sorted(d.values()), [chr(i) for i in indices])
         self.assertEqual(sorted(d.items()), [(i, chr(i)) for i in indices])
 
+    def test_dict_iter(self):
+        d = self.dict()
+        indices = list(range(65, 70))
+        for i in indices:
+            d[i] = chr(i)
+        it = iter(d)
+        self.assertEqual(list(it), indices)
+        self.assertEqual(list(it), [])  # exhausted
+        # dictionary changed size during iteration
+        it = iter(d)
+        d.clear()
+        self.assertRaises(RuntimeError, next, it)
+
     def test_dict_proxy_nested(self):
         pets = self.dict(ferrets=2, hamsters=4)
         supplies = self.dict(water=10, feed=3)

Misc/NEWS.d/next/Library/2018-09-08-12-57-07.bpo-34610.wmoP5j.rst

@@ -0,0 +1 @@
+Fixed iterator of :class:`multiprocessing.managers.DictProxy`.