diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-07-09-21-27-14.gh-issue-132657.kSA8R3.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-07-09-21-27-14.gh-issue-132657.kSA8R3.rst new file mode 100644 index 00000000000000..99f7a990875a0a --- /dev/null +++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-07-09-21-27-14.gh-issue-132657.kSA8R3.rst @@ -0,0 +1 @@ +Improve performance of :class:`frozenset` by removing locks in the free-threading build. diff --git a/Objects/setobject.c b/Objects/setobject.c index 8aa6b0d180907b..a07aad4134f752 100644 --- a/Objects/setobject.c +++ b/Objects/setobject.c @@ -85,6 +85,8 @@ set_lookkey(PySetObject *so, PyObject *key, Py_hash_t hash) int probes; int cmp; + int frozenset = PyFrozenSet_CheckExact(so); + while (1) { entry = &so->table[i]; probes = (i + LINEAR_PROBES <= mask) ? LINEAR_PROBES: 0; @@ -101,13 +103,20 @@ set_lookkey(PySetObject *so, PyObject *key, Py_hash_t hash) && unicode_eq(startkey, key)) return entry; table = so->table; - Py_INCREF(startkey); - cmp = PyObject_RichCompareBool(startkey, key, Py_EQ); - Py_DECREF(startkey); - if (cmp < 0) - return NULL; - if (table != so->table || entry->key != startkey) - return set_lookkey(so, key, hash); + if (frozenset) { + cmp = PyObject_RichCompareBool(startkey, key, Py_EQ); + if (cmp < 0) + return NULL; + } else { + // incref startkey because it can be removed from the set by the compare + Py_INCREF(startkey); + cmp = PyObject_RichCompareBool(startkey, key, Py_EQ); + Py_DECREF(startkey); + if (cmp < 0) + return NULL; + if (table != so->table || entry->key != startkey) + return set_lookkey(so, key, hash); + } if (cmp > 0) return entry; mask = so->mask; @@ -2234,10 +2243,16 @@ set_contains_lock_held(PySetObject *so, PyObject *key) int _PySet_Contains(PySetObject *so, PyObject *key) { + assert(so); + int rv; - Py_BEGIN_CRITICAL_SECTION(so); - rv = set_contains_lock_held(so, key); - Py_END_CRITICAL_SECTION(); + if (PyFrozenSet_CheckExact(so)) { + rv = set_contains_lock_held(so, key); + } else { + Py_BEGIN_CRITICAL_SECTION(so); + rv = set_contains_lock_held(so, key); + Py_END_CRITICAL_SECTION(); + } return rv; }