diff options
| -rw-r--r-- | Lib/_weakrefset.py | 10 | ||||
| -rw-r--r-- | Lib/weakref.py | 29 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Core and Builtins/2021-08-23-19-55-08.bpo-44962.J00ftt.rst | 1 |
3 files changed, 28 insertions, 12 deletions
diff --git a/Lib/_weakrefset.py b/Lib/_weakrefset.py index b267780f0c..2a27684324 100644 --- a/Lib/_weakrefset.py +++ b/Lib/_weakrefset.py @@ -51,10 +51,14 @@ class WeakSet: self.update(data) def _commit_removals(self): - l = self._pending_removals + pop = self._pending_removals.pop discard = self.data.discard - while l: - discard(l.pop()) + while True: + try: + item = pop() + except IndexError: + return + discard(item) def __iter__(self): with _IterationGuard(self): diff --git a/Lib/weakref.py b/Lib/weakref.py index a968139f98..994ea8aa37 100644 --- a/Lib/weakref.py +++ b/Lib/weakref.py @@ -119,14 +119,17 @@ class WeakValueDictionary(_collections_abc.MutableMapping): self.data = {} self.update(other, **kw) - def _commit_removals(self): - l = self._pending_removals + def _commit_removals(self, _atomic_removal=_remove_dead_weakref): + pop = self._pending_removals.pop d = self.data # We shouldn't encounter any KeyError, because this method should # always be called *before* mutating the dict. - while l: - key = l.pop() - _remove_dead_weakref(d, key) + while True: + try: + key = pop() + except IndexError: + return + _atomic_removal(d, key) def __getitem__(self, key): if self._pending_removals: @@ -370,7 +373,10 @@ class WeakKeyDictionary(_collections_abc.MutableMapping): if self._iterating: self._pending_removals.append(k) else: - del self.data[k] + try: + del self.data[k] + except KeyError: + pass self._remove = remove # A list of dead weakrefs (keys to be removed) self._pending_removals = [] @@ -384,11 +390,16 @@ class WeakKeyDictionary(_collections_abc.MutableMapping): # because a dead weakref never compares equal to a live weakref, # even if they happened to refer to equal objects. # However, it means keys may already have been removed. - l = self._pending_removals + pop = self._pending_removals.pop d = self.data - while l: + while True: + try: + key = pop() + except IndexError: + return + try: - del d[l.pop()] + del d[key] except KeyError: pass diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-08-23-19-55-08.bpo-44962.J00ftt.rst b/Misc/NEWS.d/next/Core and Builtins/2021-08-23-19-55-08.bpo-44962.J00ftt.rst new file mode 100644 index 0000000000..6b4b9dfd8b --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2021-08-23-19-55-08.bpo-44962.J00ftt.rst @@ -0,0 +1 @@ +Fix a race in WeakKeyDictionary, WeakValueDictionary and WeakSet when two threads attempt to commit the last pending removal. This fixes asyncio.create_task and fixes a data loss in asyncio.run where shutdown_asyncgens is not run
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