http://hg.python.org/cpython/rev/978525270264 changeset: 91359:978525270264 branch: 3.4 parent: 91357:a941bb617c2a user: Victor Stinner <victor.stinner@gmail.com> date: Tue Jun 24 22:37:53 2014 +0200 summary: asyncio: Log an error if a Task is destroyed while it is still pending files: Lib/asyncio/futures.py | 3 + Lib/asyncio/tasks.py | 13 +++ Lib/test/test_asyncio/test_base_events.py | 3 +- Lib/test/test_asyncio/test_tasks.py | 45 ++++++++++- 4 files changed, 60 insertions(+), 4 deletions(-) diff --git a/Lib/asyncio/futures.py b/Lib/asyncio/futures.py --- a/Lib/asyncio/futures.py +++ b/Lib/asyncio/futures.py @@ -169,6 +169,9 @@ res += '<{}>'.format(self._state) return res + # On Python 3.3 or older, objects with a destructor part of a reference + # cycle are never destroyed. It's not more the case on Python 3.4 thanks to + # the PEP 442. if _PY34: def __del__(self): if not self._log_traceback: diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py --- a/Lib/asyncio/tasks.py +++ b/Lib/asyncio/tasks.py @@ -32,6 +32,7 @@ _DEBUG = (not sys.flags.ignore_environment and bool(os.environ.get('PYTHONASYNCIODEBUG'))) +_PY34 = (sys.version_info >= (3, 4)) _PY35 = (sys.version_info >= (3, 5)) @@ -181,6 +182,18 @@ self._loop.call_soon(self._step) self.__class__._all_tasks.add(self) + # On Python 3.3 or older, objects with a destructor part of a reference + # cycle are never destroyed. It's not more the case on Python 3.4 thanks to + # the PEP 442. + if _PY34: + def __del__(self): + if self._state == futures._PENDING: + self._loop.call_exception_handler({ + 'task': self, + 'message': 'Task was destroyed but it is pending!', + }) + futures.Future.__del__(self) + def __repr__(self): res = super().__repr__() if (self._must_cancel and diff --git a/Lib/test/test_asyncio/test_base_events.py b/Lib/test/test_asyncio/test_base_events.py --- a/Lib/test/test_asyncio/test_base_events.py +++ b/Lib/test/test_asyncio/test_base_events.py @@ -244,7 +244,8 @@ @mock.patch('asyncio.base_events.logger') def test__run_once_logging(self, m_logger): def slow_select(timeout): - time.sleep(1.0) + # Sleep a bit longer than a second to avoid timer resolution issues. + time.sleep(1.1) return [] # logging needs debug flag diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py --- a/Lib/test/test_asyncio/test_tasks.py +++ b/Lib/test/test_asyncio/test_tasks.py @@ -5,13 +5,16 @@ import types import unittest import weakref +from test import support from test.script_helper import assert_python_ok +from unittest import mock import asyncio from asyncio import tasks from asyncio import test_utils +PY34 = (sys.version_info >= (3, 4)) PY35 = (sys.version_info >= (3, 5)) @@ -1501,9 +1504,45 @@ def test_corowrapper_weakref(self): wd = weakref.WeakValueDictionary() def foo(): yield from [] - cw = asyncio.tasks.CoroWrapper(foo(), foo) - wd['cw'] = cw # Would fail without __weakref__ slot. - cw.gen = None # Suppress warning from __del__. + + @unittest.skipUnless(PY34, + 'need python 3.4 or later') + def test_log_destroyed_pending_task(self): + @asyncio.coroutine + def kill_me(loop): + future = asyncio.Future(loop=loop) + yield from future + # at this point, the only reference to kill_me() task is + # the Task._wakeup() method in future._callbacks + raise Exception("code never reached") + + mock_handler = mock.Mock() + self.loop.set_exception_handler(mock_handler) + + # schedule the task + coro = kill_me(self.loop) + task = asyncio.async(coro, loop=self.loop) + self.assertEqual(asyncio.Task.all_tasks(loop=self.loop), {task}) + + # execute the task so it waits for future + self.loop._run_once() + self.assertEqual(len(self.loop._ready), 0) + + # remove the future used in kill_me(), and references to the task + del coro.gi_frame.f_locals['future'] + coro = None + task = None + + # no more reference to kill_me() task: the task is destroyed by the GC + support.gc_collect() + + self.assertEqual(asyncio.Task.all_tasks(loop=self.loop), set()) + + mock_handler.assert_called_with(self.loop, { + 'message': 'Task was destroyed but it is pending!', + 'task': mock.ANY, + }) + mock_handler.reset_mock() class GatherTestsBase: -- Repository URL: http://hg.python.org/cpython