diff --git a/Lib/multiprocessing/process.py b/Lib/multiprocessing/process.py index bca8b7a0047..f9c22703df2 100644 --- a/Lib/multiprocessing/process.py +++ b/Lib/multiprocessing/process.py @@ -104,6 +104,9 @@ class BaseProcess(object): _cleanup() self._popen = self._Popen(self) self._sentinel = self._popen.sentinel + # Avoid a refcycle if the target function holds an indirect + # reference to the process object (see bpo-30775) + del self._target, self._args, self._kwargs _children.add(self) def terminate(self): diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py index e76c4570220..871a34e4b26 100644 --- a/Lib/test/_test_multiprocessing.py +++ b/Lib/test/_test_multiprocessing.py @@ -191,6 +191,12 @@ def get_value(self): # Testcases # +class DummyCallable: + def __call__(self, q, c): + assert isinstance(c, DummyCallable) + q.put(5) + + class _TestProcess(BaseTestCase): ALLOWED_TYPES = ('processes', 'threads') @@ -398,6 +404,18 @@ class _TestProcess(BaseTestCase): p.join() self.assertTrue(wait_for_handle(sentinel, timeout=1)) + def test_lose_target_ref(self): + c = DummyCallable() + wr = weakref.ref(c) + q = self.Queue() + p = self.Process(target=c, args=(q, c)) + del c + p.start() + p.join() + self.assertIs(wr(), None) + self.assertEqual(q.get(), 5) + + # # #