* Make `weakref.WeakSet` safe against concurrent mutations while it is being iterated.
`_IterationGuard` is no longer used for `WeakSet`, it now relies on copying the underlying set which is an atomic operation while iterating so that it can be modified by other threads.
Copying and pickling instances of subclasses of builtin types
bytearray, set, frozenset, collections.OrderedDict, collections.deque,
weakref.WeakSet, and datetime.tzinfo now copies and pickles instance attributes
implemented as slots.
Fixes:
Traceback (most recent call last):
File "/home/graingert/projects/asyncio-demo/demo.py", line 36, in <module>
sys.exit(main())
File "/home/graingert/projects/asyncio-demo/demo.py", line 30, in main
test_all_tasks_threading()
File "/home/graingert/projects/asyncio-demo/demo.py", line 24, in test_all_tasks_threading
results.append(f.result())
File "/usr/lib/python3.10/concurrent/futures/_base.py", line 438, in result
return self.__get_result()
File "/usr/lib/python3.10/concurrent/futures/_base.py", line 390, in __get_result
raise self._exception
File "/usr/lib/python3.10/concurrent/futures/thread.py", line 52, in run
result = self.fn(*self.args, **self.kwargs)
File "/usr/lib/python3.10/asyncio/runners.py", line 47, in run
_cancel_all_tasks(loop)
File "/usr/lib/python3.10/asyncio/runners.py", line 56, in _cancel_all_tasks
to_cancel = tasks.all_tasks(loop)
File "/usr/lib/python3.10/asyncio/tasks.py", line 53, in all_tasks
tasks = list(_all_tasks)
File "/usr/lib/python3.10/_weakrefset.py", line 60, in __iter__
with _IterationGuard(self):
File "/usr/lib/python3.10/_weakrefset.py", line 33, in __exit__
w._commit_removals()
File "/usr/lib/python3.10/_weakrefset.py", line 57, in _commit_removals
discard(l.pop())
IndexError: pop from empty list
Also fixes:
Exception ignored in: weakref callback <function WeakKeyDictionary.__init__.<locals>.remove at 0x00007fe82245d2e0>
Traceback (most recent call last):
File "/usr/lib/pypy3/lib-python/3/weakref.py", line 390, in remove
del self.data[k]
KeyError: <weakref at 0x00007fe76e8d8180; dead>
Exception ignored in: weakref callback <function WeakKeyDictionary.__init__.<locals>.remove at 0x00007fe82245d2e0>
Traceback (most recent call last):
File "/usr/lib/pypy3/lib-python/3/weakref.py", line 390, in remove
del self.data[k]
KeyError: <weakref at 0x00007fe76e8d81a0; dead>
Exception ignored in: weakref callback <function WeakKeyDictionary.__init__.<locals>.remove at 0x00007fe82245d2e0>
Traceback (most recent call last):
File "/usr/lib/pypy3/lib-python/3/weakref.py", line 390, in remove
del self.data[k]
KeyError: <weakref at 0x000056548f1e24a0; dead>
See: https://github.com/agronholm/anyio/issues/362#issuecomment-904424310
See also: https://bugs.python.org/issue29519
Co-authored-by: Łukasz Langa <lukasz@langa.pl>