diff --git a/Lib/multiprocessing/process.py b/Lib/multiprocessing/process.py index f6b03b192ae..16c4e1eb343 100644 --- a/Lib/multiprocessing/process.py +++ b/Lib/multiprocessing/process.py @@ -128,6 +128,9 @@ class Process(object): else: from .forking import Popen self._popen = Popen(self) + # 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 _current_process._children.add(self) def terminate(self): diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py index 9fcd3bdad41..69bd8f79a85 100644 --- a/Lib/test/test_multiprocessing.py +++ b/Lib/test/test_multiprocessing.py @@ -175,6 +175,12 @@ def get_value(self): # Testcases # +class DummyCallable(object): + def __call__(self, q, c): + assert isinstance(c, DummyCallable) + q.put(5) + + class _TestProcess(BaseTestCase): ALLOWED_TYPES = ('processes', 'threads') @@ -355,6 +361,18 @@ class _TestProcess(BaseTestCase): p.join(5) self.assertEqual(p.exitcode, reason) + 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) + + # # #