Refuse handlers if the child watcher has no loop attached #391
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Will push this before b2. |
| # Clear the handlers for FastChildWatcher to avoid a warning. | ||
| # Is that a bug? | ||
| if sys.platform != 'win32': | ||
| asyncio.get_child_watcher()._callbacks.clear() |
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This is something new... Is there any reason you do this as part of this PR?
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Yes, otherwise a warning from f7a5259 is generated. Weirdly enough it only happens with the FastChildWatcher. There might be a better way to address this issue though.
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I just had a deeper look and we can get rid of this addition by fixing FastChildWatcher (using some SafeChildWatcher code):
diff --git a/asyncio/unix_events.py b/asyncio/unix_events.py
index 54cfc75..5ffa645 100644
--- a/asyncio/unix_events.py
+++ b/asyncio/unix_events.py
@@ -937,7 +937,15 @@ def _do_waitpid_all(self):
pid, status = os.waitpid(-1, os.WNOHANG)
except ChildProcessError:
# No more child processes exist.
- return
+ if not self._callbacks:
+ return
+ # Some child processes are already reaped
+ # (may happen if waitpid() is called elsewhere).
+ pid = next(iter(self._callbacks))
+ returncode = 255
+ logger.warning(
+ "Unknown child process pid %d, will report returncode 255",
+ pid)
else:
if pid == 0:
# A child process is still alive.
This also allows us to get rid of some complexity in test_sigchld_child_reaped_elsewhere:
diff --git a/tests/test_unix_events.py b/tests/test_unix_events.py
index 6cf4417..b4a6d80 100644
--- a/tests/test_unix_events.py
+++ b/tests/test_unix_events.py
@@ -1318,12 +1318,7 @@ def test_sigchld_child_reaped_elsewhere(self, m):
with self.ignore_warnings:
self.watcher._sig_chld()
- if isinstance(self.watcher, asyncio.FastChildWatcher):
- # here the FastChildWatche enters a deadlock
- # (there is no way to prevent it)
- self.assertFalse(callback.called)
- else:
- callback.assert_called_once_with(58, 255)
+ callback.assert_called_once_with(58, 255)
@waitpid_mocks
def test_sigchld_unknown_pid_during_registration(self, m):
All the tests run OK after those modifications. Let me know which solution you prefer.
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Not so sure about this solution. Let's keep the current hack-ish code.
| @@ -1396,7 +1397,11 @@ def test_set_loop_race_condition(self, m): | |||
| with mock.patch.object( | |||
| old_loop, "remove_signal_handler") as m_remove_signal_handler: | |||
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| self.watcher.attach_loop(None) | |||
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How about using with self.assertWarnsRegexp?
| @@ -898,6 +905,12 @@ def __exit__(self, a, b, c): | |||
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| def add_child_handler(self, pid, callback, *args): | |||
| assert self._forks, "Must use the context manager" | |||
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| if self._loop is None: | |||
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@asvetlov Could you please help me with reviewing this PR? |
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Sorry for a long delay. |
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Looks like I should update my pytest fixtures for |
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@asvetlov Andrew, I'm on vacation, and I can't commit this myself right now. If you have time, could you please commit this pr (and merge it to cpython 3.5/3.6/default)? |
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Committed by hand. Thanks, Vincent! |
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See also http://bugs.python.org/issue28368 |
This PR follows up on the discussion from issue #390:
This has been tested against the example from issue #390.