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gh-120858: PyDict_Next should not lock the dict (#120859)

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PyDict_Next no longer locks the dictionary in the free-threaded build. Locking
around individual PyDict_Next calls is not sufficient because the function
returns borrowed references and because it allows concurrent modifications
during the iteraiton loop.

The internal locking also interferes with correct external synchronization
because it may suspend outer critical sections created by the caller.
This commit is contained in:
Sam Gross 2024-06-24 14:15:15 -04:00 • committed by GitHub
parent dee63cb359
commit 375b723d58
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4 changed files with 34 additions and 8 deletions
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8
Objects/dictobject.c
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@ -2808,8 +2808,6 @@ _PyDict_Next(PyObject *op, Py_ssize_t *ppos, PyObject **pkey,
if (!PyDict_Check(op))
return 0;
ASSERT_DICT_LOCKED(op);
mp = (PyDictObject *)op;
i = *ppos;
if (_PyDict_HasSplitTable(mp)) {
@ -2882,11 +2880,7 @@ _PyDict_Next(PyObject *op, Py_ssize_t *ppos, PyObject **pkey,
int
PyDict_Next(PyObject *op, Py_ssize_t *ppos, PyObject **pkey, PyObject **pvalue)
{
int res;
Py_BEGIN_CRITICAL_SECTION(op);
res = _PyDict_Next(op, ppos, pkey, pvalue, NULL);
Py_END_CRITICAL_SECTION();
return res;
return _PyDict_Next(op, ppos, pkey, pvalue, NULL);
}