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[3.14] gh-132657: avoid locks and refcounting in frozenset lookups (GH-136107) #141772

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Merged
merged 1 commit into from
Nov 20, 2025
Merged

[3.14] gh-132657: avoid locks and refcounting in frozenset lookups (GH-136107) #141772

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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2025-07-09-21-27-14.gh-issue-132657.kSA8R3.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Improve performance of :class:`frozenset` by removing locks in the free-threading build.
35 changes: 25 additions & 10 deletions Objects/setobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,8 @@ 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;
Expand All @@ -102,13 +104,20 @@ 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;
Expand Down Expand Up @@ -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;
}

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