gh-91090: Make started multiprocessing.Process instances and started multiprocessing.managers.BaseManager instances serialisable

Lib/multiprocessing/managers.py

@@ -476,6 +476,12 @@ class State(object):
     STARTED = 1
     SHUTDOWN = 2
 
+    def __getstate__(self):
+        return self.value
+
+    def __setstate__(self, state):
+        self.value = state
+
 #
 # Mapping from serializer name to Listener and Client types
 #
@@ -731,6 +737,15 @@ def temp(self, /, *args, **kwds):
             temp.__name__ = typeid
             setattr(cls, typeid, temp)
 
+    def __getstate__(self):
+        state = vars(self).copy()
+        state['shutdown'] = state['shutdown']._key
+        return state
+
+    def __setstate__(self, state):
+        vars(self).update(state)
+        self.shutdown = util._finalizer_registry[self.shutdown]
+
 #
 # Subclass of set which get cleared after a fork
 #

Lib/multiprocessing/popen_fork.py

@@ -81,3 +81,12 @@ def _launch(self, process_obj):
     def close(self):
         if self.finalizer is not None:
             self.finalizer()
+
+    def __getstate__(self):
+        state = vars(self).copy()
+        state['finalizer'] = state['finalizer']._key
+        return state
+
+    def __setstate__(self, state):
+        vars(self).update(state)
+        self.finalizer = util._finalizer_registry[self.finalizer]

Lib/multiprocessing/popen_spawn_win32.py

@@ -129,3 +129,12 @@ def terminate(self):
 
     def close(self):
         self.finalizer()
+
+    def __getstate__(self):
+        state = vars(self).copy()
+        state['finalizer'] = state['finalizer']._key
+        return state
+
+    def __setstate__(self, state):
+        vars(self).update(state)
+        self.finalizer = util._finalizer_registry[self.finalizer]

Lib/test/_test_multiprocessing.py

@@ -807,6 +807,23 @@ def test_forkserver_sigkill(self):
         if os.name != 'nt':
             self.check_forkserver_death(signal.SIGKILL)
 
+    def test_process_pickling(self):
+        if self.TYPE == 'threads':
+            self.skipTest(f'test not appropriate for {self.TYPE}')
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.subTest(proto=proto):
+                proc = self.Process()
+                proc.start()
+                # Calling set_spawning_popen with a value other than None
+                # allows pickling the authentication keys of processes
+                # (.authkey), which is prevented by default in
+                # AuthenticationString for security reasons.
+                multiprocessing.context.set_spawning_popen(0)
+                serialized_proc = pickle.dumps(proc, protocol=proto)
+                multiprocessing.context.set_spawning_popen(None)
+                deserialized_proc = pickle.loads(serialized_proc)
+                self.assertIsInstance(deserialized_proc, self.Process)
+
 
 #
 #
@@ -2920,7 +2937,26 @@ def test_mymanager_context_prestarted(self):
         manager.start()
         with manager:
             self.common(manager)
-        self.assertEqual(manager._process.exitcode, 0)
+        # bpo-30356: BaseManager._finalize_manager() sends SIGTERM
+        # to the manager process if it takes longer than 1 second to stop,
+        # which happens on slow buildbots.
+        self.assertIn(manager._process.exitcode, (0, -signal.SIGTERM))
+
+    def test_mymanager_pickling(self):
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.subTest(proto=proto):
+                manager = MyManager()
+                manager.start()
+                # Calling set_spawning_popen with a value other than None
+                # allows pickling the authentication keys of processes
+                # (.authkey), which is prevented by default in
+                # AuthenticationString for security reasons.
+                multiprocessing.context.set_spawning_popen(0)
+                serialized_manager = pickle.dumps(manager, protocol=proto)
+                multiprocessing.context.set_spawning_popen(None)
+                deserialized_manager = pickle.loads(serialized_manager)
+                self.assertIsInstance(deserialized_manager, MyManager)
+                manager.shutdown()
 
     def common(self, manager):
         foo = manager.Foo()

Misc/NEWS.d/next/Library/2022-11-30-11-25-08.bpo-46934.zk8HaW.rst

@@ -0,0 +1,3 @@
+Make started :class:`multiprocessing.Process` instances and started
+:class:`multiprocessing.managers.BaseManager` instances serialisable. Patch by
+Géry Ogam.